Are you paying too much for your HVAC equipment? How do you know if the quote you received for your equipment is a fair price? Do you have a method of comparing what you have paid for various HVAC equipment with what is being quoted currently?
Keeping track of the cost of HVAC Equipment allows you to quickly provide budgets and check the cost of equipment before you purchase. This database allows you to easily keep track of the most common HVAC equipment.
HVAC Equipment Cost Database
Using an HVAC Equipment cost database will save you a lot of money by avoiding the costly mistake of paying too much for equipment.
Air Conditioners in Historical Pricing HVAC Equipment Database
The HVAC Equipment Cost database keeps track of all your equipment quotes or purchases for easy reference and parametric checks, such as cost per ton ($/Ton), cost per CFM ($/CFM)
For an HVAC Piping & Plumbing Estimator the need for quick budgets for the installation of piping is best handled with a matrix of different material types and sizes. Having an estimating software program can make this process a lot easier as the material pricing is always up to date and can be entered into the matrix quickly.
HVAC Piping Unit Pricing Calculator
UNIT PRICING
Often the requirements of the RFP or bidding instructions will call for the price per foot to install piping beyond that which is required by the contract drawings. Such pricing maybe used for change-orders. Having these numbers available and updated often also gives you a quick reference for budgeting projects. It’s good to know when doing job site comparisons of different piping options or during discussions with engineering, what the cost is for the various piping sizes and types of materials.
HVAC Piping Unit Pricing Calculator for Copper and Carbon Steel from 1/2″ to 14″
COST PER FOOT
The cost per foot for the installation of piping needs to include fittings and hangers prorated into the value. It’s best to look at a standard length of pipe and then figure that you will have a Tee and 90 degree elbow in that length. So for example, using twenty feet of copper water pipe with a Tee and 90 degree elbow plus the hangers to build a unit price would represent a field condition of a fitting every ten feet. For higher density projects like Hospitals you could put more fittings in your unit pricing. Total those cost up and then divide by 20 to derive at a cost per foot for that particular size and material type.
20 feet of pipe + 2 Fittings + 3 Hangers / 20 = Cost per Foot
If the piping is insulated, you can also put the values in for insulation.
The Estimating Wizard provides two spreadsheets for tracking unit pricing, one for HVAC Piping and the other for Plumbing piping. Get a copy and start tracking your cost per foot, or be prepared to give a quick budget based on your knowledge from your spreadsheet of unit prices. Watch the video on the estimating Wizard website and see how quick and easy it is to track the cost per foot for various sozes and material types.
MEP Academy HVAC Piping Unit Pricing Calculator
The MEP Academy provides a spreadsheet that makes calculating unit pricing simple. The spreadsheet is available on the MEP Academy website https://mepacademy.com
HVAC Piping Unit Pricing Calculator Example
In the screenshot above there is a place for you to build your hanger requirements (#1), and a place to put your tax rate and hourly labor rate (#2).
For each size of pipe and material type you would insert the unit cost for Material (#3) and Labor (#4).
Under item (#5) you would build your typical run of pipe and enter the quantity of fittings you might expect for the type of building and system. You would add whatever you think will be required for every so many feet of pipe. In the example above we are showing that for every 20 feet of pipe you will have 1 Elbow and 1 Reducing Tee.
Under item (#6) you would add the cost per lineal foot for insulation if required. You could also look at insulation as a separate value and leave the pipe bare.
Line item (#7) is where you indicate the hanger spacing, and for each hanger you defined under item (#1) you will get the quantity as defined by the linear feet in item (#5) divided by your hanger spacing, which will affect your cost.
Line item (#8) is the calculated cost per linear foot of piping for that size and material type of pipe.
Summary Sheet
After you have all your unit pricing information inputted into the spreadsheet, all you have to do to get a budget for installing piping is to enter the quantity of piping (#9) for each size and material type (#10). The system will automatically calculate the cost (#11) to install that run of piping based on your unit pricing data. The total cost will be shown at the top of the spreadsheet (#12).
The proper sizing and layout of condensate drain lines is important for the protection of property and for the proper functioning of the air conditioning equipment.
If you prefer to watch our YouTube version of this presentation, scroll to the bottom.
Condensate Drain Pipe Sizing
The size required for the condensate pipe is dictated by the local code. Enclosed you will find the requirements for many local codes, but be sure to check your code for your local requirements. If the outlet size of the equipment’s condensate drain is larger than what’s shown in this chart then your required to use the larger outlet size.
Minimum Condensate Drain Pipe Sizing Chart
Slope to be at least 1/8” per foot or 1 percent, that is for every 12” horizontally there must be at least an 1/8” drop vertically.
Condensate drain piping to slope a minimum of 1/8″ per every 12″ horizontal
Attics or Furred Spaces
If the Air Conditioner is suspended above an inaccessible ceiling, such as a gypsum board ceiling or attic space then you will need to provide a means for protecting the building elements from the overflow of the primary drain and for indicating that there is a leak.
Also, drain pans that are poorly drained can cause water to stay in the pan risking the possibility of algae and bacteria growth. Below are some possible solutions, but as always check your local code for the approved method.
Option 1 – Secondary drain pan with drain piping. This would hang below the Air Conditioning unit in case the A/C units primary pan overflowed. Also, there is a requirement to provide secondary drain piping to a point of termination that would provide notification to the occupants that there is a leak, such as terminating above a window or doorway.
Option 1 – Secondary drain pan with piping terminating in observable location
Option 2 – An additional drain pipe connection that sits above the primary drain connection and whereby the secondary drain piping terminates in a location to alert the occupants of the clogged primary drain.
Option 2 – Secondary drain piping connection to primary drain pan
Option 3 – Leak detection device that automatically shuts down the Air Conditioner if the primary drain becomes clogged.
Option 3 – Primary drain with leak detection device
Option 4 – Secondary drain pan with leak detection, located beneath the coil that shuts down the unit upon a leak.
Option 4 – Secondary drain pan with leak detection
The additional drain pan or drain pan connection shall be provided with a drain pipe that will determinate in an observable area, such as in front a window or above a doorway, and be of a size not less than 3/4”. Secondary drain pan shall not be less than 1-1/2” in height and extend 3” wider on each side of the coil or AC unit.
Secondary drain piping terminating above window. Pipe doesn’t have to be visible as shown.
Drain Termination
Where can and can’t you terminate the air conditioners condensate drain piping? There are several options where you can terminate the condensate drain line;
Indirect Drain
Condensate Pump to Indirect Drain
Drywell
Leach pits
Landscaped areas that are properly designed to handle the volume of condensate
To Properly designed stormwater treatment systems.
Indirect Drain
Lavatory tailpiece in the same tenant space as the air conditioner
Laundry standpipe
Janitors Sink
Inlet of Bathtub Overflow – Must be accessible
Collect and send to cooling tower (See description below)
Cooling Coil condensate to sink tailpiece.
The connection to a plumbing fixtures tailpiece has to be made within the same tenant space as the air conditioner cooling coil that is generating the condensate.
Drywell
A drywell can be used for the termination of your air conditioners condensate drain. Check your local code for the specifics, but generally it includes some or all of the following depending on whether it’s for residential or a commercial project:
A minimum size hole, such as 2 foot by 2 foot by 3 feet deep, or a round hole such as 12” diameter by 3 feet deep.
A minimum of 6” of soil or concrete shall provide cover above the rocks
Some form of barrier between the soil and the top of the drywell where the rock begins, such as building paper or plastic
Drywell to be filled with gravel or crushed rock, often with a stated minimum size rock such as 1 inch diameter
The termination of the condensate drain pipe shall connect indirectly to the drywell drain pipe.
The drywell drain pipe to be a minimum of 1-1/2” PVC or other approved material.
Drywell to be at least three feet away from the building structure or any footings.
Drywall for Air Conditioner Cooling Coil Condensate
There are various methods of providing drywells depending on the local code. There are prefabricated drywells that can be used and ones that are made by using a large diameter piece of PVC pipe or similar material.
Some codes will require you to collect the condensate from cooling coil drain pans and return it to the cooling tower if the equipment is served by a cooling tower and the total combined capacity of the HVAC cooling coils exceeds a certain amount like 65,000 btu/hr.
This is a water conservation measure, and there are some exceptions to this requirement, such as if the total capacity of the AC Equipment cooling coils are less than 10% of the total capacity of the cooling tower, or if the location of those AC Cooling coils are in a remote location, far from the tower.
Some locations where you can’t terminate condensate;
Public ways
Sidewalks
Driveways
Alleys
No termination of condensate on public area ways
Excluded from Code Requirements
Excluded from these codes are non-condensing type of equipment like radiant cooling panels that are designed to prevent condensate from occurring by keeping the temperature of the chilled water above the dew point temperature/vapor pressure of the surrounding air. These are system designed to operate in sensible cooling only modes.
Piping Material
The material types that can be used for condensate drain piping varies by jurisdiction but the most commonly cited materials are:
Copper
PVC – DWV
CPVC
ABS – DWV
Polyethylene
Galvanized steel
Cast iron.
Also the use of short radius 90-degree elbows are often prohibited. You can normally use standard fittings until you reach a certain size at which point you might be required to use drainage pattern fittings (DWV)
Traps
Traps are to be installed as required per the manufactures recommendation. No traps are required on the secondary drain pan, this is to allow immediate notification that the primary drain has failed.
Cleanouts
Cleanouts are required in case of plugged drain pipes. Provide as required to prevent the need to cut drain pipes for unplugging. Some of the following maybe used for cleanouts if approved by your local code authority;
Plugged tees
Union connections
Short clamped hoses at the unit (see image above)
When you have more than one air conditioning unit condensate tied to a main condensate pipe, then every change of direction shall have some method of cleanout. Check your local code as this maybe a requirement for even a single air conditioners condensate piping.
Condensate Pumps
Condensate pumps can be used to elevate the condensate vertically to a point where it will then discharge into a code approved gravity sloping condensate drain line. The condensate pump should be interlocked with the Air Conditioning Unit to prevent its operations if the condensate pump is inoperable.
Please remember that code requirements are always changing, so check for the most current code in your area at the time of design and installation. Or ask an inspector for the current installation practice.
Having an MEP Academy Estimating Spreadsheet that automates portions of your estimates saves you valuable time that you could use to make more sales. All aspects of the cost of furnishing and installing an HVAC or Plumbing system is contained in one spreadsheet made specifically for the MEP industry. New Electrical section coming soon.
Dashboard
The Main Dashboard provides you with all the information you need to make a quick decision on whether to make further adjustments, or if one of the metrics looks out of place based on historical data. The Dashboard gives you a quick overview of all that is going on within the Estimating Spreadsheet.
Estimating Dashboard within the MEP Academy Estimating Spreadsheet
Your MEP Academy Estimating Spreadsheet needs to be able to handle rental equipment, general conditions, subcontractors, piping and plumbing takeoffs, sheet metal, labor rate tables with crew mix capabilities, , and a bid summary. Each sheet in the estimating spreadsheet automatically calculates the values you enter, showing you a new total bid amount.
Will cover portions of the MEP AcademyEstimating Spreadsheet starting at the back of the Excel spreadsheet and working our way toward the front summary page last.
Choose your crew mix based on the level of experience and the different pay scales based on each project. Pick any combination and quantity of tradesman based on the requirements of the project.
Labor Rates and Crew Size within the MEP Academy Estimating Spreadsheet
There is a separate crew labor rate for HVAC Piping Shop & Field, Sheet Metal Shop & Field, and Plumbing.
Enter the project equipment price and labor to rig the HVAC and Plumbing equipment into place. Compare supplier pricing easily side by side. The MEP Academy Estimating Spreadsheet automatically selects the lowest bidder but lets you override that decision.
HVAC Equipment page within the Estimating SpreadsheetHVAC & Plumbing Equipment Sheets
Do you need a jobsite trailer or onsite management? Enter the quantity and level of the staff required to run the project, whether one person or dozens. Set the quantity and duration of each general condition, along with the rate. General Conditions is broken down into three sections as follows: #1 – Management, #2 – Construction Office (Non-Reoccurring Expenses), and #3 – Construction Office (Reoccurring Expenses).
HVAC & Plumbing contractors often subcontract out for Air & Water Balance, Sheet Metal & Piping Insulation, Water Treatment, Building Automation, Excavation and other specialty trades that they don’t self-perform. This spreadsheet was made especially for the HVAC & Plumbing contractor and their most often used subcontractors.
For those contractors that do plumbing the following Plumbing Fixture sheet will give you a place to record your vendors quotes and the labor it takes to install each type of fixture. What is also revealed is the overall cost per fixture.
Plumbing Fixtures page within the Estimating Spreadsheet
Each trade has a specialty sheet for those items that aren’t considered equipment or a fixture, but for which there is a cost impact. The MEP Academy Estimating Spreadsheet includes Sheet Metal, HVAC Piping & Plumbing Specialty sheets.
HVAC and Plumbing Specialty Pages within the Estimating SpreadsheetSpecialty Sheets in Estimate Spreadsheet
Material & Labor Summary Sheets
You will find a Sheet Metal, HVAC Piping & Plumbing material & labor summary sheets where all of the other specialty sheets are summarized for your review and last minute edits. Each sheet will be divided between field & shop fabrication work. The first section covers the field installation items.
Sheet Metal Material and Labor Summary – Estimating Spreadsheet
Each of the field labor summary sheets contain a row to add for the following
Material Handling
Consumables
Punch List
Cleanup
Detailing
Supervision
Shop Fabrication Summary Section
For those of you that have a fabrication shop, there is a section to add material and labor.
Shop Fabrication Summary
Rentals
For those HVAC air conditioning and Plumbing projects that require a crane, fork lift, scissor lift or any other equipment that you don’t own but will be required on the project. Having a spreadsheet that maintains a list of the most common equipment you normally rent along with their rental rate will save you time and money while avoiding having to call for pricing on every job.
Rental Sheet in Estimating Spreadsheet
Engineering
If you do your own design then you should have a sheet of each of the personnel responsible for spending time on the engineering task. If you’re doing design/build work, but don’t do the engineering yourself, but hire a third party, then you should add some engineering review time. It’s your responsibility to manage your third-party engineer to make sure they design within your cost parameters.
All of your estimates are summarized on the last tab of the MEP Academy Estimating Spreadsheet for easy review. You can quickly scan each of the categories to see where all the project cost has shown up. There is the labor and material summary for HVAC Sheet Metal, HVAC Piping, and Plumbing and another section for Subcontractors, General Conditions, Rentals, etc.
Estimating Spreadsheet Summary PageMEP Academy Estimating Spreadsheet Summary
The MEP Academy Estimating Spreadsheet contains a bid risk assessment form that rates the success of winning any particular project that you are contemplating pursuing. The risk assessment form will help you determine if the project is worth bidding based on a set of questions that rate your answers.
Bid Risk Assessment
The answers to these questions will give you a score from which you can use to see how the project rates on a scale of risk and reward. The total risk assessment score will also inform you which level of approval is required within your company depending on how you rate your risk values as the example shown below. The total score is 25, which according to this contractor would require the Vice President to sign-off on the project or approve the decision to pursue bidding on the project.
The MEP Academy Estimating Spreadsheet is used to gather all the information for estimating a project, putting it into a format where you can make quick adjustments and decisions while the spreadsheet gives you an immediate update on the price.
Purchase this spreadsheet at its currently reduced price of ONLY $195.00, which usually sells for $599.00
Watch the YouTube video below to see the MEP Academy Estimating Spreadsheet in action.
Basic HVAC Controls. Most modern residential and commercial building are built with some form of an HVAC systems to control the interior environment. These HVAC systems are used to control temperature, pressure, humidity, flow, and air quality. In this video we’ll show you how these HVAC systems use various controls to respond to the needs of the environments that they seek to control.
Scroll to the bottom for a FREE YouTube Video of this Presentation.
The importance of the HVAC system is usually appreciated on the hottest or coldest days of the year when you really notice the difference between outdoors and the controlled indoor environment. The HVAC systems are designed to be able to meet the peak demand for each of the seasons, summer highs and winter lows. Most of the year the HVAC system will run at partial load, where the full capacity of the system is not used.
The demand on the HVAC system changes throughout the year and daily. HVAC systems are sized based on Heating and Cooling loads, often performed by load calculation software. Below are some of the most common load calculation and energy modeling software.
HVAC Load Calculation and Energy Modeling Software
The load calculations will take into consideration the solar load on the structure, the quantity of people in each space, heat from lights, and the plug load, which is all the equipment and appliances that use power and generate heat within the building.
HVAC Cooling Load Sources
The HVAC control system will need to respond to these changes to maintain the environmental conditions such as Temperature, Pressure, Humidity, and Air Quality. HVAC systems can be used to control the environment for people, food, cleanroom processes for computer chip manufactures or pharmaceutical drugs, animals, IT equipment in data centers, and hospital procedures. The scope of application is endless, but we’ll stick to the control of the environment for humans.
HVAC systems use some form of controls from the very basic to the very sophisticated BMS, Building Management Systems that can monitor and control everything from the HVAC system, lighting, fire systems, and security systems.
We can control a simple single standalone piece of equipment like a home air conditioner or hundreds of pieces of HVAC equipment all networked together and controlled from a frontend computer in the facility managers office or remotely.
On/Off Control
The most basic form of control is to turn on and off a piece of equipment with an on/off switch. You have two options, either the equipment can be on or off. This can be done with a simple light switch as an example.
Carbon Monoxide Garage Exhaust System
We’ll use an underground parking garage for our example, as everyone has been in one of these. With a simple on/off switch we can turn the garage exhaust fan on when the garage is occupied and shut it off when all the cars leave. Not very efficient, and against code in most jurisdictions.
We can automate this by adding a carbon monoxide controller and sensor to activate the fan when the total CO level reaches the setpoint of the controller.
Carbon Monoxide Controller for Garage Exhaust System using a VFD for Fan Speed Control
The CO Sensor will send an analog input signal to the carbon monoxide controller indicating the current CO concentration, and when the set point of the controller is reached, meaning that the level of CO in the garage has reached a level that requires the exhaust fan to be turned on, the controller will send a binary signal to the fan to start.
This input device or CO transmitter senses if there is a buildup of car exhaust. We can now add more controls for better energy efficiency, such as a VFD.
Now the CO sensor sends the current concentration of CO in the garage to the controller. The controller will compare that to the setpoint, if the input signal CO levels is greater than the controller setpoint, the controller will send an analog output signal to the VFD, variable speed drive to speed up the fan. The output signal is considered an analog signal because it can vary. The speed of the fan will be based on the level of CO in the garage. Instead of on/Off, we can provide the proper fan speed to match the exact conditions in the garage, helping to avoid using too much energy.
We can still add a few more binary output devices to bring attention to a dangerous situation. By adding two more output devices, a strobe light, and a horn we can notify garage occupants that the levels of carbon monoxide have reached a dangerous level. The carbon monoxide controller will have a setting that sends a binary signal to the horn and emergency strobe light to turn on when the CO exceeds a hazardous level.
Garage Exhaust – Carbon Monoxide Controller and Sensor with Emergency Horn and Strobe Light
You can see that using a controller allows you to add input and output points to any system. The garage exhaust fan can be setup to run at low and high speed or if acceptable to the local code be run using a VFD.
Controllers, Sensors and Controlled Devices
Now we’ll explain the function of the controller, sensors, and controlled devices.
There are four basic elements of a control system: controller, sensor, the controlled device, and the source of energy, such as electrical or pneumatic.
These special sensors monitor and measure variables like, temperature, humidity, pressure, flow, and air quality and provide controllers with the status of the space. These parameters can’t be done with a simple on/off setting. The analog input and output devices send or receive a variable current, voltage or resistance between a minimum and maximum value. This allows for an accurate measurement.
HVAC Controls Input and Output Points – Analog and Binary
There are different types of signals produced by sensors, which include: Electronic, Pneumatic or Electric Sensors. Pneumatic systems are prone to leaks and are being changed out whenever possible as they are less energy efficient than DDC.
Pneumatic sensors put out a 3 psig to 15 psig pressurized air signal, electronic sensors can be resistance, voltage, or current based sensors, with a voltage signal range of 0 to 10vdc, a current signal range of 4 to 20 mA (milliamps)
The controller is the brain that makes the decisions based on settings entered by the controls company according to the specifications and sequence of operation. The controller receives inputs from sensors and compares that to the controllers setpoint and then provides a response to output devices. The inputs inform the controller of the existing environmental condition, and then the controller directs the output devices to change the environment to meet the setpoint.
Much like your brain is the controller taking input from your senses, like taste, smell, hearing, vision, and sense of touch. The brain will take the input from your senses and direct an output signal on what the body should do with that information, such as move hand away from hot stove, or spit out a hot pepper, or a visual input of a man with gun, will provide the response or output to run away fast.
There are all kinds of input and output devices for controlling the environment. Each device is meant to serve a particular purpose.
The difference between a binary and analog input or output device is the number of positions or steps you can have. A binary input or output device has two options, such as either on/off or start/stop, while an analog device can vary, such as in reading various temperatures and pressures, or in modulating a valve or damper position to increase flow in varying amounts, not just full open or full close.
Analog is used when the environmental element being measured has more than two options. Binary provides for two states, either on/off, low/high, start/stop, etc.
Inputs provide the controller with the information it needs to make a decision, while the outputs are where the controller sends its messages to make adjustments as required to meet the settings of the controller.
A binary input to the controller could be the fan status, whether it’s on or off, while the binary output to the fan from the controller could instruct the fan to start or stop. Each of these inputs and outputs have two options, on/off or start/stop.
An analog input to the controller could be the current speed of the fan when using a VFD, while the analog output could be used to change the speed of the fan using the VFD. Using an analog input or output allows for a range of fan speeds to be used.
Universal inputs allow for either a binary or analog input.
Now we’ll step back to explain a couple simpler devices.
Split System HVAC Unit
Using an on/off switch for your home heater or air conditioner would not be very effective because as we now know there are sensors that can measure the indoor temperature and turn on and off the HVAC unit as required. The typical home thermostat acts as the controller and temperature sensor all in one. You set the desired temperature and the thermostat will try to maintain that setpoint.
To control these environments, you need to monitor or sense the existing condition and compare it to the desired setpoint you’re trying to achieve for the space.
To automate this, we could add a simple bimetal thermostat that would sense the air temperature surrounding the stat or temperature sensor and feed that information to the HVAC equipment. When it got warm in the room the bimetal would expand and make contact in the electrical circuit, causing the air conditioner to turn on. When the air cooled down it would cause the bimetal in the thermostat to contract and pull away from the electrical contacts thereby turning off the air conditioner. Now at least you have the HVAC system automated according to temperature.
Scheduling – Time Clock Function
Adding a time clock to the thermostat or BAS will allow additional control based on day of the week or time of day. For example, you could have the thermostat turn on the air conditioner an hour before you get home from work so that the home is already cool when you arrive. A simple timeclock allows the HVAC system to have its own schedule based on time, while the thermostat will be based on temperature. So, with a simple thermostat we can control temperature and time.
With the increase in mobile apps, most of this can be done on your phone, but you’ll still need the hardware component to communicate with your AC unit.
Scheduling is important in commercial buildings because you don’t want the occupants to arrive in the morning on a very cold day to find their offices freezing cold. Another reason is that you want to make sure that the HVAC system can’t run on weekends or during the night when the building is unoccupied as this would be a big waste of energy and money.
With building automation software and their control logic the schedule and the temperature and be optimized beyond just starting an hour before the occupant’s arrival. The automation software will look to optimize the starting and stopping of the HVAC system to provide for energy savings. So, the control program will check with other input devices such as an outside air temperature sensor and zone temperature sensors to determine when to bring on the heating or cooling to meet the design temperature before the occupants arrive.
This will help the controls program calculate how long it might take to heat up the building before the occupants arrive. The colder the outside air the longer it will take to warm up the building, so the earlier the HVAC system heating mode will be turned on.
VAV Box Control
A VAV box is commonly found in medium to large commercial buildings, so this will help explain the basic control sequence for this design. You can see that the VAV Box Controller (#1) is mounted on the VAV box and receives an analog input from the room temperature sensor (#2), meaning it can provide a wide range of temperature readings, the Discharge Air Temperature sensor (#3) is another analog input device, and Airflow Sensor (#4).
VAV Box Controller Diagram
In heating mode, the VAV box controller receives input from the room’s temperature sensor that it’s too cold in the space, the controller then sends a signal to the Damper Actuator (#5) which is an analog output device, to close the damper to minimum position and start to modulate the Heating Hot Water control valve (#6) open, another analog output device.
The controller being the brains, receives input information on which to compare against the setpoint, and then sends an output command to various components to achieve the desired environmental conditions set for this space.
In heating mode, the VAV box damper will be at the minimum open position to avoid wasting energy, as the air arriving at the VAV box has been cooled down at the Air Handler to around 55°F (13°C). We will build on this system by introducing the VAV system and additional control points.
VAV Air Handler System Control
In a VAV system we can add another component of control and that is fan speed. Fan’s use a lot of energy and so being able to reduce their speed will save money. See our video on fan laws to understand the savings potential, and our video on VAV systems which are commonly used in larger commercial buildings.
Fan speed is accomplished by adding a static pressure sensor in the main supply air ductwork. The static pressure sensor is an analog input device which measures the static pressure in the duct. As VAV zone dampers reduce their need for air, they close their dampers causing the pressure in the main supply air duct to increase which is sensed by the static pressure sensor.
The controller will receive the input signal from the pressure sensor that the pressure has increased, and then send a message to the fan to slow down by use of a VFD, variable speed drive. The controller compares the static pressure in the main supply duct to the setpoint and then modulates the supply fan VFD to maintain that static pressure setpoint. As the demand for cooling decreases more, the static pressure setpoint can be reset downward to save additional energy. To learn more about variable speed drives see our Video on VFD’s.
Fan Coil System Control
A similar device in a water-based system would be a differential pressure controller combined with two-way valves on the coils. In a heating hot water or chilled water system, as the modulating 2-way control valves at each coil begin to close, the increased pressure is sensed by the differential pressure controller, an analog input device. This sends a signal to adjust the pump speed using a VFD to reduce the frequency or hertz delivered to the motor on the pump, thereby reducing the flow of water. VFD’s are used to control cooling towers, chillers, pumps, and fans.
Fancoil system HVAC controls
All these points can be monitored by the BAS, building automation system for a more optimized and energy efficient system.
Flow Control Valve
Using a thermostat with a control valve connected to a fan coil or radiator we can control the flow of heating hot water or chilled water, either of two ways. First, the 2-way flow control valve can be either a two-position valve, that is either open or closed (binary), or modulating (analog). Using a two position control valve, when there is a demand for cooling or heating, the control valve opens all the way and you get full water flow whether you need it or not.
HVAC fan coil controls
The second method would have a modulating or proportional control valve accept a varying analog signal, like 4 to 20 milliamps. Instead of two positions, full open or full closed, the valve will have various percentages of open. The analog input temperature sensor sends a signal to the fan coil controller indicating the current temperature of the space. The controller compares the current temperature in the space to the desired set point. The greater the distance from the setpoint, the greater will be the response to open the valve.
The controller accepts the input temperature from the sensor, compares it to the set point in its control logic, and then sends an analog output signal to the device being controlled. The controlled device then responds by trying to change the controlled environmental element, in this case it’s the temperature by opening the 2-way control valve an increasing the flow of hot or cold water through the coil.
Sequence of Operation
In the commercial controls industry, you’ll hear the term sequence of operation. This is the defined method or sequence upon which the controls are to respond as defined by the mechanical or controls engineer. It defines how the controller along with the input and output devices will achieve control of the environment or space, whether that is a room occupied by humans, animals, or equipment, whether it’s an ice box or central plant. The sequence of operation explains how the system is designed to operate.
Sequence of operation – control of exhaust fan
Points List
The points list is a quick reference chart that list all the input and output points required to meet the sequence of operation strategy. You’ll find these on commercial construction control drawings. Here is the one for our simple Garage Exhaust CO Monitoring Controls System.
HVAC Controls Points List
Control Drawings
The control drawings provide a schematic diagram of where and how the individual control devices are connected overall.
Lumens and Footcandles. We’ll show you how to choose the correct light bulb when switching out an old incandescent bulb, we’ll explain lumens, footcandles and Lux for those using the metric system. We’ll show you how footcandles change with the square of the distance, and how to calculate foot candles.
If you prefer to watch the YouTube version of this presentation, scroll to the bottom.
Replacing Light Bulbs – Buy the Lumens, Not the Watts
It used to be easy to switch out incandescent light bulbs based on how many watts they used, because all you had to do was go to the store and pickup one that matched the watts. With the need for increased energy efficiency and the increased use of LED lights, this doesn’t work anymore.
The latest bulbs use up to 80% less power to give you the same amount of light. Switching from incandescent to LED using the same watts doesn’t work. It’s the lumens that you want to match. Buy the Lumens, not the watts. The higher the lumens, the brighter the light.
Match the Lumens of your Old Incandescent with the Lumens of a new Energy Efficient light
When changing from incandescent to LED or other energy saving bulb, it’s the lumens that represents the brightness, not the wattage. If you maintain the same distance from the light bulb to the floor or task area, then getting the equivalent lumens should work.
Here is a rule of thumb from the government energy savers program.
When replacing an incandescent bulb
Replace a 100-watt incandescent bulb with a light bulb that provides about 1,600 Lumens.
Replace a 75-watt light bulb, with one that provides about 1,100 lumens.
Replace a 60-watt light bulb, with one that provides about 800 lumens.
And replace a 40-watt light bulb, with a light bulb that provides about 450 lumens.
Replacing incandescent light bulbs with equivalent in Lumens, not watts
Lighting Facts Label
When shopping for light bulbs, look at the label on the package and you should see the lumens listed as shown here.
Lighting Facts Label on all Light Bulb Packages
The label will provide you with the lumens, the estimated savings based on an assumption of your cost per kw, the projected life of the bulb based on daily hours used, the appearance of the light from a warm yellowish color to a cooler blue appearance, and the energy consumed in watts.
What is a Footcandle?
A footcandle is defined as a measurement of the light’s intensity. One foot candle equals the amount of light to saturate a one-foot square with one lumen of light.
Footcandle.
What this means is that the number of lumens produced by the light source, whether that’s an office light fixture or a lamp at home is measured not by how many lumens leave the bulb, but by how many reach the surface being measured and it’s expressed in foot candles.
Footcandles would tell us how much of the light that leaves the fixture arrives at the surface where it’s needed.
Why use Footcandles
Using footcandles allows different sources of light to be compared and provide a standard that can be measured. Footcandles are directly affected by the distance from the source of lumens and can be expressed in a simple formula.
Footcandles = Lumens/ (Distance in Feet)2
This makes the distance from the source a main factor, and the distance works inversely with the footcandles.
If you had a 10-Watt LED light with 800 Lumens, then you could figure your footcandles using the formula starting with the lamp 1 foot off the floor we get
Footcandles = 800 Lumens / (1 foot) 2
Footcandles = 800 / 1 = 800 Footcandles.
The lumens and the footcandles match as the distance is only 1 foot.
Moving the lamp to 4 feet above the floor we now get
Footcandles = 800 Lumens / (4 feet) 2
Footcandles = 800 Lumens / (16) = 50 FC
Again, this time at 8 feet above the floor we get
Footcandles = 800 Lumens / (8 Feet) 2
Footcandles = 800/64 = 12.5 FC
Using that same 10-watt LED light, but hanging it at 10 feet, instead of 8, the footcandles or amount of useful light changes at the surface.
Footcandles = 800 Lumens / (10 feet) 2
Footcandles = 800/100 = 8 FC
This clearly shows the relationship between distance and footcandles, and that the lumens can remain the same but have very different results based on height.
Footcandles and the effects of distance.
This is common sense to all of us, but this formula makes it easy to calculate the affect and gives illuminating engineers something to use in laying out the lighting design to ensure proper lighting for the various areas of the building.
We can see that if the distance is only 1 foot, then our lumens will equal our footcandles as that is the definition.
What does the IES Recommend?
The IES, or better known as the Illuminating Engineering Society provides a standard for lighting levels for various surfaces, such as the following: Operating room 1,000 Footcandles. This is definitely important because the medical staff needs to see clearly. Classrooms 100 footcandles, Gymnasium 100, offices 50, factory floor 30, hallways 10 and a parking lot only 2 footcandles.
IES Requirements for Footcandles based on space type
For anyone trying to read in a parking lot at night, now you know why its difficult, because they’re only designing to achieve a few footcandles of light.
LUX and the Metric System
For those using the metric system, this would be expressed in LUX. One footcandle is equal to 10.764 Lux.
Lumens expressed in SI Units of Lux per square meter
Remember that our formula for footcandles was based on 1 square foot. Since a square meter has 10.764 square feet, then we need to multiply our footcandles by 10.764 to get the equivalent footcandles/m2.
Lumens expressed in IP and SI units. (Footcandles and Lux)
It’s the same amount of footcandles, it’s just expressed for a larger area, because instead of 1 square foot, we are using 10.764 square feet or 1 square meter.
Data Center HVAC Systems. Data centers have HVAC Cooling Systems that differ from your standard air conditioning system because they cool information technology equipment (ITE), instead of people. This IT equipment requires much more cooling than a room full of people. The average person sitting gives off 400 to 450 Btu/hour, while one rack of IT Equipment can give off between 17,060 Btu/hour (5 kw) to 102,360 Btu/hour (30 kw). Data centers are energy intensive, and are growing more so.
If you prefer to watch the FREE YouTube Video of this then scroll to the bottom of the page.
Heat produced by Air-Cooled and Liquid Cooled IT Equipment Racks
We’ll explain the various HVAC systems that serve Data Centers, including air-cooled and liquid-cooled IT equipment. We’ll explain the three most popular data center system strategies, such as room, aisle, or in-row cooling. You’ll learn about proper air management in Air-Cooled systems.
With the explosion in growth of the web and social media, the farming of cryptocurrency and online commerce, data centers are in demand to hold all the data that supports these online activities.
Data centers never shut down which is a huge drain on energy, as these facilities run 24 hours a day, 7 days a week, 365 days a year, never taking a break. All those servers and support equipment running continuously causes a large heat load that needs to be removed from the IT Equipment to function optimally.
Racking
All the IT equipment sits on shelfs arranged vertically in a rack. The standard rack height is 7 feet (2.1m). These racks lined up together in neat rows in data centers. The racks house and protect data center equipment such as servers, routers, switches, hubs, and audio/visual components. The data center IT equipment can get very hot, so cooling is required to keep them from overheating and for proper operation. Racks in data centers are either air-cooled or liquid cooled.
Air-Cooled Racks
Cold air is brought through the front of the rack, across the IT equipment where it picks up heat, and then the hot air exits the back of the rack.
Data Center HVAC System – Air Cooled IT equipment Racks in Data Center
To increase the efficiency, blanking plates are added to direct the cold air optimally over the IT equipment positioned in the rack, and to keep the warm air from mixing with the cold entering air. It’s important to cover openings within and between racks to avoid wasting energy and directing the cold air where it is needed.
Liquid-Cooled Racks
Liquid cooling works better for racks with power densities between 5kw and 80kw, while the traditional air-cooled rack power densities are between 1kw to 5kw.
There are many different designs for liquid-cooled racks, here are four types.
Racks with integral coils
Rear Door Heat Exchanger
Liquid on-board cooling
Liquid immersion cooling
Liquid cooled IT equipment Racks in Data Center
Here is a liquid-cooled rack with integral coil or heat exchanger. The cold liquid circulates through a heat exchanger located in the rack. There are small fans that circulate air over the IT Equipment to capture the heat and bring it to the Cold Heat Exchanger, thereby absorbing the heat into the liquid and sending cold air over the IT equipment. This is one type of liquid cooled system, but there are many different versions with each manufacture trying to achieve greater efficiencies with their designs.
Liquid has the capacity to transfer heat up to 4X higher than the capacity of air of the same mass. This makes liquid cooled systems the ideal choice for the ever-increasing heat loads of rack equipment.
We looked at several rack configurations, let’s see how they are organized in the overall data center layout.
Data Center Layouts
You walk down aisles between racks lined up in rows on both sides in a typical data center. These aisles are either receiving cold air or rejecting hot air from the IT equipment. So, you’re walking down either a hot or cold aisle.
The traditional method was to use no containment of either the hot or cold air within these aisle in the data center. The thinking was to push the supply air up through the raised floor hoping the majority would make it through the rack before mixing with the hot air. With the increase in heat being generated per rack growing, this strategy of uncontained air is inefficient. There are better more efficient solutions, but first let’s explain a little about raised floors.
Raised Floors – Supply Air Plenum
Raised floors are common in larger data centers using air-cooled systems. A raised floor can be supported from 6” to 30” off the main floor to provide a supply air plenum space. The cold air delivered to the underfloor plenum will be supplied to the IT equipment through tiny holes in the floor tiles. Not all floor tiles in the space have these tiny holes in them, but only where needed to provide cold air.
Raised Floor in Data Center
The cold air will flow through these perforated tiles and enter the servers, picking up their heat, causing the heated air to rise above the servers where the return air suction of the HVAC units pulls the warmed air back into the cooling unit. All the server racks are facing the same direction to control the flow of air in one direction.
There are many options for providing the cold air or liquid that is circulated to the racks, here are a few of those.
Data Center HVAC Equipment Types
The most efficient strategy in air-cooled systems is to capture the heat before it mixes with the cold air. This avoids mixing the two air streams, the hot and cold air. There are three common methods of distributing the air to the racks, and that is either room, row or racked based.
Data Center Room Based Design
The most efficient solution is to implement an air management strategy.
Air Management
Proper air management in data centers dictates that you should keep the cold and hot air from mixing. It’s important that the cold supply air enter the heat-generating IT equipment without mixing with the hot exhaust.Heat should be returned to the cooling system without mixing with the cold air.
By separating the supply air from the return air within the space a more efficient system can be created. This containment strategy is better than the traditional non-containment methods.
This provides for delivering cold supply air in one aisle and removing warm return air in another. The server racks are arranged so that the cool air flows through them from the cold side through the warm IT equipment and into the warm aisle before returning to the top of the CRAC unit where the return air opening is located.
No containment of the hot or cold air in this data center with a raised floor supply air plenum
Cold air is pressurized in the underfloor plenum causing the supply air to flow through the perforated floor tiles aligned in the cold aisle. Cold air enters the IT equipment racks and absorbs the heat before being discharged into the hot aisle. Warm air from the hot aisle is pulled back to the CRAC or CRAH unit. This transfers the heat from the IT equipment to the DX or Chilled water coil where it will then be expelled outside.
Since the room is completely open with no physical barrier between the supply/cold aisle and the return/hot aisles there are some losses occurring due to mixing of the supply and return air. Hot air will migrate over the rack and be recirculated back into the top front of the rack, causing short-circuiting and a loss of efficiency.
Inefficiency can be resolved by establishing a cold or hot aisle containment strategy. Either of these methods will increase the efficiency of the cold supply air entering the Rack and avoid mixing. Aisle containment improves energy efficiency while allowing for uniform inlet temperatures for IT equipment and avoiding hot spots.
Temperature entering the IT equipment must be set correctly, as too low of a supply air temperature waste energy, while too high of a supply temperature leaves the rack temperature too hot.
When designing High Density data centers, its best to use the Hot Aisle Containment strategy, as insufficient cold air reaches the racks in the CAC arrangement.1
Cold Aisle Containment (CAC)
By isolating the cold air to just the front of the server racks with no opportunity to mix with the return we can increase our efficiency and delivery of the cold supply air to the front of the server racks. By putting a containment barrier on the cold aisle, we can direct the cold supply air to the front of the server where it is most useful.
Cold aisle containment strategy in a Data Center.
Cold air has nowhere to go accept through the racks where it picks up the heat from the IT equipment before entering the hot aisle where it will rise and be pulled back to the HVAC equipment. Hot air is not contained within the space.
Cold Aisle Containment in Data Center
Using the cold aisle containment method, the cold air is contained within the cold aisle, while the warm return air is allowed to circulate throughout the whole data center. The two air streams are separated by some form of containment enclosure on the supply side.
Hot Aisle Containment (HAC)
Using this strategy, the hot air being exhausted from the racks is contained to just the hot aisle and is pulled into the ductwork or a plenum and sent back to the HVAC equipment without mixing with the cold supply air. This can work with or without a raised floor, as the supply is not contained within the room.
Hot Aisle containment strategy in a Data Center
The hot aisle is enclosed keeping the hot air from the IT equipment contained, while the cold air is allowed to circulate throughout the data center, the direct opposite of the cold aisle system.
Hot Aisle Containment in a Data Center
Computer Room Units
There are several different styles and configurations of computer room HVAC equipment. Some sit on the ceiling, others sit on a raised floor, while others can sit in-row between the Racks and not require a raised floor.Traditionally the two most common HVAC systems for medium to large data centers was either a CRAC unit, that is a Computer Room Air Conditioner or a CRAH, Computer Room Air Handler. These are just a big box containing fans, cooling coils, filters, and options like humidifiers. The two units look similar, its’ just the way they cool the air that’s different.
It’s common to find a raised floor system in a data center, where the cold air is supplied to a plenum under the IT Equipment. The HVAC units are strategically located throughout the Data center floor area and provide cold area in a downflow pattern into the open plenum space below the floor.
The difference between the two is that the CRAC units are DX cooled and have a DX condenser outdoors to support the indoor unit. The CRAH unit is provided with chilled water and has a chiller as the source.
The traditional room based cooling systems are reaching the limits of their capabilities in some data centers. Higher density blade servers pack a lot of power in a small space, which means more heat. The room-based systems are designed for lower density racks and simply can’t keep up with the heat load, which can create hot spots.
To address this problem, cooling solutions can be brought closer to the source of the heat, which is generated in the rack. These systems are often referred to as close-coupled cooling systems, which can be used instead of, or in addition to standard room based cooling systems. This would include In-row and In-rack systems.
In-Row Cooling Units
In-row cooling units sit between the IT equipment racks and take the hot air from the hot aisle, and cool that air before blowing it into the cold aisle where it gets sucked into the IT equipment racks to cool down the equipment. Each of these In-row CRAC units is dedicated to one row of racks, and despite their name can be installed overhead or under the floor in addition to the in-row versions.
In-Row cooling units to cool a row of IT equipment racks in a Data Center
Being close to the racks saves on fan energy and increases energy savings. In-row CRAC units also allow for different cooling capacities per row to handle varying load profiles of the server racks. One row of racks may generate more heat than another because of the type of IT equipment in the rack.
A raised floor is not required for this design which saves money and increases floor load bearing capacity.
The hot aisle must be designed with a roof and doors on the sides to allow access. The roof and sides keep the hot air contained so it doesn’t mix with the cold air. With In-row units the source of cooling is closer to the heat load, minimizing the mixing of hot and cold air streams.
In-row cooling units can be served with chilled water, or they could be self-contained mini air conditioners that only need to be plugged into the 208/240V outlet. For higher density data centers using in-row units, chilled water would be the better solution.
Rack Cooling
There are various rack cooling designs, including directly mounted to the rack or housed within the rack itself. These systems are dedicated to one server rack.
One option is to have self-contained racks that have their own air conditioner, but these are limited in size. For higher densities you’ll have chilled water fed to these rack cooling systems. The rack can have a heat exchanger mounted on the back that absorbs the heat being ejected from the IT equipment. Up to 60 kw per rack can be achieved using this method.
In-rack Cooling of IT equipment in a Data Center
For more information see the link to the government’s energy star article for in-rack cooling.
There are some data centers that use a combination of the three systems because of the varying densities of load.
Racked based systems are more costly to purchase especially as the power density decreases. But the energy savings for a rack based system will be less annually in electricity cost.
CDU – Cooling Distribution Units
Cooling distribution units provide separation between the IT equipment in the racks and the outdoor heat rejection equipment like a cooling tower or dry cooler. The heat exchanger in the CDU keeps the two water systems separated so they never mix, allowing the liquid circulating in the racks to be unaffected by the water circulated outdoors. Water from the tower is circulated to the primary side of the heat exchanger in the CDU where it absorbs the heat from the secondary water circulating through the racks.
Inside the CDU are redundant pumps that circulate secondary water to various racks.
The CDU provides water to the IT rack equipment that is above the dew point temperature to avoid condensation issues.
Cooling distribution unit distributes cold liquid to IT equipment racks in Data Center
CDU’s can be very energy efficient because it avoids the use of refrigeration equipment like chillers and DX coils using compressors. The CDU will use a Dry Cooler or Cooling Tower for heat rejection. With some manufactures you can achieve 5kw (17,060 Btu/hr.) to 30kw (102,360 Btu/hr.) per rack of heat removal.
These systems are usually cost effective compared to most other systems. In case of a leak, they have very small volumes of water in their secondary loops compared to a chilled water system used with other rack cooling strategies.
With the amount of time spent indoors, it makes sense to find ways to increase the quality of your indoor air for yourself or your customers. Indoor air quality is often worse than the outdoor air unless you live near a factory or refinery.
We are in the business of providing quality indoor environments so we thought we would share some of the best ideas to help you make yours or your customers home safer and the quality of the air better. These top 12 are not our opinions, but facts derived from research which we’ll include links to if you want to research further.
We’re not being alarmist, but wise stewards of responsible clean living, especially if you have young children in the home, as we’ll show you ways that they are being poisoned that you may not have heard about. See the link to our website where you can download a PDF for yourself or a customer.
To watch our FREE YouTube Video of this presentation, please scroll to the bottom.
Reduce Toxins in Your Life by Following these top 12 Ways to Increase Indoor Air Quality
#1 Properly Vent Fireplaces and Stoves
Ensure that all combustion appliances such as fireplaces and wood stoves are vented properly. According to the EPA Smoke forms when wood or other organic matter burns. The smoke from wood burning is made up of a complex mixture of gases and fine particles. In addition to particle pollution, wood smoke contains several toxic air pollutants including benzene, formaldehyde, acrolein and polycyclic aromatic hydrocarbons.
Properly Vent all Combustion Processes. Avoid inhaling smoke and Particle Matter PM
You may like the smell of burning wood, but it’s definitely not good for you, especially the fine particles that are emitted. These microscopic particles can cause havoc to your eyes and your respiratory system, with the possibility of burning eyes, runny nose, and illnesses like bronchitis, the triggering of asthma, heart attacks, stroke, irregular heart rhythms and heart failure. This isn’t our opinion these are the words of the EPA, which you can check out in the link below.
Avoid or minimize the use of any unvented combustion by-products such as the burning of candles, tobacco products, un-vented heaters, indoor barbecues. The majority of candles are made of paraffin wax, which is made from petroleum waste, and when burning give off highly toxic benzene and toluene, both are known carcinogens, basically they cause cancer. If the candle is scented then there are additional concerns from the harmful effects of the chemicals in the fragrance.
Avoid Candles made from Paraffin Wax (aka Petroleum)
Use alternative candles such as those made from beeswax, coconut or 100% soy. Use candles scented with essential oils instead of toxic chemicals. Checkout the website in this link for more information. MadeSafe.org
#3 Plants per NASA and Biophilia
Fill your home with plants that provide air scrubbing abilities or by adopting the calming effects from biophilia. Biophilia is defined as the innate human instinct to connect with nature and other living things. This is done by bringing the outdoors, indoors.
Biophilia – Bring the Outdoors, Indoors & Indoor Plants for better Indoor Air Quality
According to NASA there are certain indoor plants that can absorb toxins from the indoor air. They list the top 12 indoor plants for increased indoor air quality. See the link to NASA report in the description below.
See more information on Biophilia in the link below, and how you can increase indoor well-being by bringing the outdoors, indoors.
Dust can contain harmful Toxins especially for small children
#4 Clean on a Regular Schedule
Clean on a regular schedule using a quality vacuum cleaner, microfiber cloths and non-toxic alternative cleaners and methods. Toxins stick to house dust and soil that is brought into the house. These toxins can be inhaled when dust is kicked up, while some could also be unknowingly absorbed through the skin or swallowed by hand-to-mouth contact. If you have small children, remember they spend a lot of time on the floors where some of these toxins can gather.
#5 Vent Smells
Make sure that all the rooms where smells are generated are properly vented to the outside. This would include bathrooms, laundry rooms, kitchens. The quality of the air is improved when smells are exhausted outdoors. If you have a fan powered kitchen or range hood be sure to put the fan on high speed when cooking to force any products of combustion or smells out of the home.
Open Windows for Fresh Air when the weather allows
#6 Toxins, Smells Generated Indoors – Open Windows
When cleaning or using products with strong odors be sure to open as many windows as possible to move the vapors and smell outdoors. This would include odors from nail polish as research has shown that women who work in poorly vented nail salons have higher rates of birth defects among their newborns. Even if you’re not a salon worker its best to do your nails in the backyard or a well vented area. See research paper below.
Avoid breathing in Toxins from Nail Polish and other hazardous chemicals
Also if using a spray bottle to spray your cleaner, realize that some of that cleaner will be aerated into the breathable air. Spray close to the surface or spray into your cleaning cloth. It’s even better to use a cleaner that is safe for you and the environment. Use green products, and visit the EPA website which provides plenty of healthier alternatives, see the link below.
Never store toxic, volatile, or hazardous compounds within the home. This might include pesticides, herbicides, paints, glue, cleaners, and similar items. These items could leak into the air stream at levels unnoticeable to you. And when using make sure to read the label and ventilate the space, and avoid having children around if possible. See the link in the description below for the report on Pesticides and Asthma. It’s always best to use safer, green alternatives. Checkout the Safer Choice website below for safer alternatives.
The industry standard for indoor air quality is from ASHRAE, the American Society of Heating, Refrigerating and Air-Conditioning Engineers. ASHRAE standard 62.2, Ventilation and Acceptable Indoor Air Quality in Low-Rise Residential Buildings provides guidance on this topic.
Make sure to provide the ASHRAE minimum ventilation per standard 62.2. This can be done using a whole house fan. The ventilation rate is based on the size of the home and the number of bedrooms. If you have a 3 bedroom, 2,000 Ft2 (185 m2) home then you need 90 CFM or 43 L/s of ventilation air.
Whole House Fan – Indoor Ventilation
Of course this can only be done with the proper weather conditions existing outdoors, and is usually a summer application. In summer, opening the windows during early morning or evening hours when the air is cooler can bring the temperature down and freshen the air inside. See ASHRAE standard 62.2 for more information.
Don’t locate heating and air conditioning equipment in the garage or an area where the system or ductwork could inadvertently suck in toxins from car exhaust or toxic substances stored in the garage. Also be sure to have your furnace inspected to ensure there aren’t any leaks which is a silent killer. Gas and oil burning furnaces produce carbon monoxide (CO). Carbon monoxide is an invisible, odorless, poison gas that kills hundreds every year and makes thousands more sick. Install battery backed up carbon monoxide detectors in every bedroom. See link below in the video description to the CDC’s website for more information.
Use a good quality filter or high-efficiency portable air cleaner in your HVAC system, one that filters out the dust and particles circulating in the air. The use of a MERV 13 filter or higher is best if your system can accommodate them. If you choose a portable air cleaner make sure that it doesn’t emit ozone. Make sure to replace your filters after frequent use and according to the manufactures recommendation.
#11 Avoid Products with Toxic Flame Retardants
Avoid purchasing products for your home sprayed with flame retardants that are considered toxic. These flame retardants can be in furniture, carpet padding, baby products and pajamas. These flame retardants can become airborne, settle on dust and items in your home. Small children often have higher levels of flame retardants in their bodies because they put their hands and household items in their mouths, causing them to swallow these toxins.
Fire Retardants in Furniture and elsewhere
See the EWG’s website on where these flame retardants can be found in your home and what you can do about it.
Avoid using plug-in air fresheners and other air fresheners unless you know their ingredients, as a lot of the products on the shelves today could be carrying toxic chemicals. The manufactures often refuse to disclose the ingredients claiming they are a trade secret. What’s not a secret is that these air fresheners can be toxic, including negative health effects like cancer, endocrine disruptions and neurotoxicity.
3 Phase Electricity – How it Works. We’ll be demonstrating how 3 phase electricity works by first explaining how its generated, and how it differs from single phase electricity. We’ll also cover where 3 phase power is used in industrial and commercial buildings.
To watch the FREE YouTube version of this presentation, scroll to the bottom.
How is 3 Phase Electricity Generated?
If starting at the source of 3 phase power generation, we would begin at the power generation plant, whether that was nuclear, fossil fuel or another source. AC Generators convert mechanical energy into electrical energy, while the AC motor does the opposite, it converts the electrical energy into mechanical energy like turning the motor shaft of a pump or fan.
3 Phase AC Generator Converts Mechanical Energy into Electrical Energy
The AC generator could be a steam powered turbine fed by a boiler burning coal, gas, oil or another source, such as nuclear power or a hydroelectric dam. The steam or potential energy turns the generator that produces the 3 phases we’ll be discussing now. We’ll show you a coal burning plant convert coal into electricity later.
Michael Faraday – Electromagnetic Induction and Electromagnetism
First we must pay tribute to Michael Faraday, an English Scientist who contributed to the study of electromagnetism and the principles underlying electromagnetic induction. AC Generators and Motors use electromagnetic induction as we’ll now explain.
Electromagnetic Induction
A magnetic field can be created in a conductor by passing electricity through it, or an electrical current can be induced in a conductor by passing a magnetic field past the conductor. We can accomplish this with three items, a conductor, electromagnets and movement between them.
There are many version of the AC Generator, one such version uses a rotating electromagnet to create a magnet field that conductors pass through, thereby creating electromotive force and inducing current to flow in the conductors. Another version would have the conductors moving and the electromagnets are stationary. The commonality is a electromagnet which creates a magnetic field and a conductor that is brought within this magnetic field.
3 Phase Magnetic Induction
When the north pole of the Electromagnet passes the electrical conductor windings it induces current to flow in the wire.
When the magnet is 90 degrees past the conductor windings than no current flows in the wire.
3 Phase Electricity Magnetic Induction – No current Flow
As the South pole of the electromagnet passes the conductor windings it causes the current to travel in the opposite direction as that caused by the North pole of the magnet. This causes the current to be alternating in direction as represented by the wave form.
3 Phase Electricity generated by Electromagnetism
There are three coils in 3 phase electricity, with an angle of 120 degrees between them.
3 Phase Electricity – Frequency in Hertz
What is 3 Phase Electricity
Using what we learned previously we can now assemble a basic 3 phase generator by adding three sets of windings, one for each phase. The previous single winding can be considered a single phase generator. Will need to put these windings in a housing to hold everything together.
Here is what a simple single phase generator might look like.
Single Phase Electricity
Now as the electromagnet rotates within the stator, its magnetic field cuts through the conductors inducing current to flow in an alternating back and forth pattern. Using only one conductor we get a single phase system.
Adding two more conductors we now get three phase electricity. The magnetic field of the electromagnet now penetrates the three conductors inducing current to flow in all three conductors. We get three separate phases that are 120 degrees apart giving us the most effective arrangement for power use.
3 Phase Electricity using an Electromagnet
As the magnetic field of the North pole of the magnet reaches the nearest point of one of the conductors it will force electrons and current to flow in one direction. Then when the South Pole of the electromagnetic reaches that same conductor it will causes the electrons or current to flow backwards. This back and forth push and pull of the electrons or current in the three separate windings is how three phase power is created.
While one conductor or winding is peaking in strength facing the North pole of the magnet, the others are 120 and 240 degrees away, awaiting their turn at the effects of the North pole of the magnet. This occurs 60 times in a second giving us 60 hertz, or if you’re in a country that uses 50 hertz, this will occur 50 times a second.
A complete rotation of all three phases equals one cycle, and in a 60 hertz system, that would mean 60 cycles or rotations of the rotor within the stator housing every second, for a 50 hertz system, 50 cycles per second. The cycles per second is called frequency, and is either 50 or 60 hertz. Remember motors with VFD’s can very their hertz, and if you aren’t familiar with this concept then see our video on VFD’s, Variable Frequency Drives.
Coal Burning Electricity Plant
The 3 phase electricity is generated here using dirty coal. Coal is sent to the boiler where it is burned to create steam that turns a turbine in the generator that produces the electricity. The electricity is transmitted over high voltage lines to location that will consume the electricity. The high voltage electricity will be converted to lower voltage by running it through a transformer.
Coal Powered Electricity Generation
These transformers can be located on an industrial or commercial property where the voltage will be reduced to something that is at a proper level for the equipment it will power.
Depending on the configuration of the transformer, it can be setup as a delta or Wye type transformer providing all the various voltages required in the building. From this 3 phase electricity everything in the building can be powered whether requiring single or 3 phase. The lights in your home will use 115 volts or something similar while a commercial building may use 277 volts, single phase for their light fixtures, as 277V is more efficiently distributed.
Your home will only require single phase electricity while commercial and industrial buildings can use the more efficient and powerful 3 phase power for their equipment, such as Pumps, Fans, Chillers, Elevators, hospital equipment, etc. The 3 phase power allows the industrial and commercial buildings to also use just a single hot wire to get single phase to run office equipment like computers, vending machines, calculators and other low voltage items.
Learn how OHM’s Law Works, and how to use it to solve problems.
To watch the FREE YouTube version of this presentation, scroll to the bottom.
What is Ohm’s Law
There is a relationship between Voltage, Current and Resistance that is easily explained using Ohm’s Law. The German physicist by the name of Georg Ohm develop the theory that we are going to explain here.
What is Ohm’s Law
We can calculate any of the three factors that make up the OHM’s law, if we have any two of the factors. Here are the three versions of the formula.
Voltage (V) = Current (I) x Resistance (R).
Current (I) = Voltage (V) / Resistance (R).
Resistance (R) = Voltage (V) / Current (I).
OHMs LAW WHEEL
The formulas are easily remembered by using the Ohm’s Law Wheel. You may also see version of this using a Triangle.
Ohm’s Wheel
Each of the three formulas is represented by one of the three wheels, with the product were trying to solve colored red. All you have to do is cover the red letter or the letter that you’re trying to solve for. For example, if you cover the “V” for voltage, than you’ll only see the Current (I) and Resistance (R). When the letters are side by side you multiply, when the “V” voltage is over any letter, than you divide into the voltage.
Ohm’s Wheel – Easy method for determining formula for Ohm’s Law
Just cover up the letter you want to solve for, and the formula will reveal itself.
Solving for Amps
Using a digital meter, we can determine how many amps are flowing through a circuit like this here.
Ohm’s Law for Solving for Amps
If we cover up the (I) of the Ohm’s wheel with an effort to solve for the amps or current flowing through the system, we can see that the two known values of 6 volts and 2 ohms of resistance work perfectly within the formula. This gives us 6 volts divided by 2 ohms = 3 amps.
Doubling the Voltage
By putting batteries in series, you add up the total of the voltage. As shown in the example here, the two 6-volt batteries in series equal 12 volts.
Ohm’s Law for determine Amps when Voltage is doubled
By doubling the voltage and keeping the resistance the same, we have effectively doubled the amps. We now have 12 volts divided by the same 2 ohms of resistance to get twice as many amps as previously, 6 amps instead of 3.
Remember since voltage is always in the numerator position, anytime you increase the voltage there will be an increase in amps if the resistance stays the same.
Doubling the Resistance
By doubling the resistance and keeping the voltage the same, we have effectively cut the amps in half.
Doubling Resistance in an electrical circuit will cut the amps in half.
The current or amps are inversely related to resistance. As resistance goes up, the current goes down, and vice versa, as the resistance in Ohms decreases, amps will increase in the circuit.
Resistance versus Amps in an Electrical Circuit with fixed voltage
Solving for Resistance (Ohms)
To find the (R) resistance in a circuit, cover up the “R” in the Ohm’s wheel and enter the two known values of Voltage (V) and Amps (I).
Solving for Resistance using Ohm’s Law
By knowing the voltage and measuring the amps flowing through the circuit we can determine the resistance. There are three 6-volt batteries that are equivalent to 18-volts, plus the digital meter reads 3 amps. With these two values we get 18-volts divided by 3 amps equals 6 Ohms.
Solving for Voltage
Solving for the voltage requires knowing the value of the resistance and the current. Using a digital meter, the amps can be determined. With this we enter the resistance and amps into the formula to discover the voltage.
Solving for Voltage using Ohm’s Law
Voltage is the force that pushes the amps through the circuit while ohm’s provide resistance to the current flow.
Other ways of Measuring
Remember there are other ways to determine the voltage, current and resistance in a circuit, but this presentation was meant to demonstrate the use of Ohm’s Law.
Voltage can be determined directly by connecting to the terminals of the batteries using a multi-meter.
Multi-meter for measuring voltage, amps and resistance
Measuring Resistance can be done with the same digital meter by setting the meter to read ohms and setting the two probes on each side of the resistor. The multi-meter has an internal battery that sends a current through the resistor.
Measuring Current or amps can be done as shown above or by using a clamp on type of amp meter that isolates a wire. Instead of being connected in series with the circuit the amp probe encompasses the wire. These clamp on meters can measure both AC and DC current.
Amp Meter – Clamp
Learn what Ohm’s Law is and How to calculate Voltage, Current and Resistance Easily
