How Electronic Expansion Valves Work

MEP Academy Instructor

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January 29, 2022

The electronic expansion valve controls the precise amount of refrigerant that flows into the evaporator. This is based on the demand which causes a step motor to open or close the valve to achieve a certain superheat that avoids liquid refrigerant from entering the compressor.

You will find expansion valves in most refrigerant circuits from refrigeration and air conditioners to chillers. The need for increased accuracy, precise temperature control, better energy efficiency and remote monitoring has brought about an evolution in expansion valves. (See below for YouTube video on Electronic Expansion Valves)

Checkout these Electronic Expansion Values here

We will cover the main components including the superheat controller, electronic expansion valve, pressure transducer and temperature sensor, along with a brief explanation of superheat.

Refrigerant Circuit using a Superheat Controller

The expansion valve is one of the four main components found in refrigerant circuits. If you missed our video on Refrigerant Circuits you can find the link here.

All refrigerant circuits need a way to control the amount of refrigerant that can pass from the high side of the system to the low side. The refrigerant passes through the expansion valve in a liquid state. Once this refrigerant passes the expansion valve it ends up going through the evaporator where the liquid refrigerant absorbs heat from the air or water that passes over the evaporator. This causes the refrigerant to evaporate, going from a liquid to a gas.

Depending on the demand for cooling, the expansion valve acts to control the proper amount of refrigerant needed.

With the superheat controller monitoring the superheat and adjusting the expansion valve to maintain an optimally low superheat value that results in higher COP values. A higher COP translates into energy savings.

There are various manufactures and types of expansion valves and variations on how they function. We’ll cover some basics about the electronic expansion valve and some of the components that allow it to operate. First we’ll cover the various components that you’ll find in some of the electronic expansion valve setups and how they function.

What is Superheat

It’s all about maintaining the correct amount of superheat. Making sure you have a minimum amount of superheated refrigerant leaving the evaporator before it enters the compressors is important for the protection of the compressor and for accurate demand control. Compressors are not made to handle liquid refrigerant, so it’s important that only gas/vapor enters the compressor, otherwise you can damage the compressor.

The superheat controller allows you to adjust the parameters and set which refrigerant is being used in the system. Each refrigerant has different characteristics of pressure, temperature and superheat values.

Checkout these Electronic Expansion Values here

Using the two buttons on the superheat controller with the visual display is easy for technicians to make any setting required or view system states such as superheat, temperature sensor value and evaporating temperature. The display and its readouts will save the technician from having to retrieve service gauges and thermometers to determine these values.

Controlling superheat is an accurate method of ensuring that you have the proper amount of refrigerant, not too little or too much refrigerant, but an energy efficient amount to meet the demand.

Superheat occurs when the refrigerant in the evaporator has completely evaporated into a gas and then additional heat is added to the gas. The initial heat caused the liquid refrigerant to turn into a gas. By adding additional heat after the refrigerant has completely changed into a gas the temperature of the refrigerant gas becomes superheated.

Superheat = Temperature of Gas entering compressor – Boiling Point/Saturation point of refrigerant.

For example if your refrigerant boils at 40 degrees (4.4 C) in the evaporator, the point at which the refrigerant liquid turns into vapor, then adding more heat will cause the temperature of the vapor to rise, let’s say to 50 (10 C) degrees. This would give you 10 degrees (5.6 C) of superheat.

Typical control is based on superheat set point but an additional temperature sensor may be used to measure discharge water or air temperatures. This air or water temperature may be controlled directly, as long as superheat remains at a level sufficient to prevent floodback.

The job of the expansion valve is to make sure that the evaporator has the optimum amount of refrigerant injected into it no matter what the load or demand is at any time. This is done by using a Superheat Controller, Pressure Transmitter/Transducer and a Temperature Sensor with the electronic expansion valve to constantly sense the superheat in the evaporator. We will cover each of these components now.

Expansion Valve Superheat Controller

The Expansion Valve Superheat Controller calculates the superheat, after which it sends a signal to open or close the expansion valve opening to allow an accurate amount of refrigerant into the evaporator based on demand.

This precisely controls the amount of refrigerant allowed through the valve based on the superheat of the refrigerant. The controller requires low voltage power and wired connections for the various input or output signals such as the pressure transducer, temperature sensor and or remote monitoring by the building automation system.

Alarm

The controller can send notification of any alarm set off by the system such as high or low superheat, bad pressure transducer or temperature sensor, minimum or maximum temperatures. This is done by the controller providing an error code on its LED display which corresponds with the manufactures trouble shooting literature to identify the problem area.

Hotkey

Look for the feature of a hotkey that allows you to program one controller and, than upload those setting to a hotkey where you can than easily transfer the settings to all other controllers needing the same settings by plugging the hotkey into all other controllers.

Remote Monitoring

This feature allows you to connect to your building automation system so that overview of the controller can be done remotely.

Battery Backup

If the system doesn’t have positive shutoff capabilities or use a solenoid valve to prevent refrigerant migration during non-operating periods such as during a power outage, then some means of power backup should be provided. That’s where this feature provides connectors for a battery backup or UPS (Uninterrupted Power Supply).

Pressure Transducer

The pressure transducer or transmitter will provide the expansion valve controller with the current pressure at the discharge of the evaporator on the suction line to the compressor.

Checkout these Refrigerant Sensors here

Temperature Sensor

The temperature sensor provides the other information needed by the electronic expansion valve controller in order to calculate the superheat of the refrigerant in the system.

Checkout these Refrigerant Temperature Sensors here

With the temperature from the sensor and the pressure from the pressure transducer the controller can determine the superheat of the refrigerant and make an intelligent adjustment to the electronic expansion valve.

Electronic Expansion Valve

The control of the amount of refrigerant flowing through the expansion valve is more accurate using an Electronic Expansion Valve EEV. This accuracy increases the efficiency and energy performance of the system by preventing wasteful amounts of refrigerant getting passed the expansion valve.

There are various manufacturers of EEV’s, such as Emerson, Danfoss, Sporlan or Carel, each with their respective benefits and features, but the premise is the same. The desire to control superheat to protect the compressor and provide an efficient amount of refrigerant is at the heart of the design of an expansion valve.

Some of the components of this particular electronic expansion valve are the #1 Permanent Magnet Motor and #2 Electric Coils that work together to adjust the #3 Needle Valve allowing #4 High Pressure Liquid Refrigerant to pass into the evaporator where it becomes #5 Low Pressure Liquid.

Electronic Expansion Valve (One View of Many Variations) — Electronic Expansion Valve (One View of Many types)

The step motor in electronic expansion valves doesn’t rotate continuously like your typical fan or pump motor. The step motor takes small steps in either direction to precisely control the amount of refrigerant going through the expansion valve. Baby steps in the tune of 200 to 400 steps per second, or a total of 2,500 steps to over 6,000 steps for larger models. One complete rotation could be 24 to 100 steps (15 to 3.6 degrees/each step) depending on the design of the valve.

Checkout these Electronic Expansion Values here

Sightglass

Parker’s Sloan Electronic Expansion Valve models SERI & SEHI have a built-in sightglass that can indicate the moisture level of the refrigerant, flash gas present upstream of the valve, and provides a visual confirmation of valve piston movement. This can be a useful feature for system refrigerant charging, service and diagnostics.

Checkout these Refrigerant Sight Glasses here

Steps to Take when selecting an Electronic Expansion Valve

Determine Refrigerant to be used
Determine capacity required for the valve
Determine pressure drop across valve
Determine the liquid temperature of the refrigerant entering the valve
Select valve from the capacity tables of the valve manufacturer

Features and Benefits

Energy Savings
Accurate Control
Optimized Superheat Control
Optimally charged Evaporator
Precise Minimum Stable Superheat (MSS) Control
Improved Part Load for Variable Speed Systems
Works with all common Refrigerants
Intelligent Superheat algorithm with Safety Features
* Compressor Protection
* Fewer Compressor Breakdowns
*Stable Operation
Easy to Install
Controller works with a Modbus interface or as a stand-alone

How Chillers Work Water vs Air-Cooled Chillers

MEP Academy Instructor

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January 22, 2022

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How Chillers Work Water vs Air-Cooled Chillers

Chillers are used to cool water that is then used to cool the occupants of buildings. The Chiller comes in two basic condenser side designs, either it’s water-cooled or air-cooled. This designation is referring to how heat is rejected from the system, either the heat is rejected by water or air.

If you prefer to watch our FREE YouTube version of this presentation, scroll to the bottom.

Main Chiller Components

There are four main components in a chiller. These same four components can be found in all air conditioning units with slight differences in configuration.

The Compressor (The Refrigerant Mover)
The Evaporator Coil (Heat Exchanger) – Absorbs Heat
The Condenser Coil (Heat Exchanger) – Rejects Heat
The Expansion Valve or Metering Device (Refrigerant Traffic Cop)

The difference between an air-cooled and a water-cooled chiller begins with the method on which they eject heat, and as their prefixes imply, one ejects heat with air the other using water. They both use the basic refrigerant circuit with modifications. Below is the standard refrigerant circuit you’ll find in just about every piece of air conditioning equipment including chillers with some modifications.

Basic Refrigerant Circuit

Notice that the evaporator and condenser both use a fan to blow air over a coil to absorb or eject heat from the refrigerant circuit. See our video on Refrigerant Circuits.

Refrigerant Circuit for Air-Cooled Chiller

The refrigerant circuit for an air-cooled chiller replaces the evaporator fan with a Shell and Tube Heat Exchanger. (See image below). The low side liquid refrigerant will enter the shell and tube heat exchanger and absorb the heat from the chilled water return. The refrigerant surrounds the tubes while the chilled water enters the tubes, the two never mix. The refrigerant circuit is completely isolated and separate from the chilled water circulating.

Refrigerant Circuit of an Air-Cooled Chiller

Refrigerant Circuit for Water-Cooled Chiller

With a water-cooled chiller we have eliminated both the condenser and evaporator fans, as water is the medium by which the heat will be passed around. We have replaced the condenser fan with a Shell and Tube Heat Exchanger where condenser water will take the heat from the High Pressure Refrigerant and eject it through a cooling tower of some sort.

As you see from the three refrigerant circuits there are always the same four components, Evaporator, Condenser, Compressor and Expansion Valve. The only real difference is in the method they absorb and reject heat (Air or Water).

Refrigerant Circuit of a Water-Cooled Chiller

Heat Source

Remember that the basic function of the chiller is to move HEAT. To absorb heat from within the building and then to toss it out of the building. It’s the process of evicting heat from the building. Remember that you make the air cooler by removing heat. Heating and cooling is accomplished by either adding heat or removing heat from any medium. Heat moves from the warmer source to the cooler one.

Where does the heat come from? It comes from the People, lights, plug loads and solar through walls, windows and the roof. There will also be heat and moisture brought in from the code required ventilation air or outside air and infiltration, air that leaks into the building. See Video on “Calculating Cooling Loads“.

Sources of heat Load for Building Cooling System — Sources of Heat

Heat Absorption Cycle

The process begins by absorbing heat from the space and any ventilation or outside air added at the Air Handler. The heat enters the air handler from the return air brought from the occupied spaces along with outside air added for ventilation. This air blows over the Chilled Water coil located in an Air Handler where it gives up its heat to the chilled-water being circulated from the chillers evaporator. The cooled air is then supplied to the room from the air handlers supply fan through sheet metal ductwork to air diffusers in the occupied space.

The chilled-water supply enters the cooling coil at about 44°F (6.6°C) and the heat is taken back to the chiller in the chilled-water return piping at approximately 54°F (12.2°C). The chilled water has increased 10°F (6.6°C) by absorbing the heat from the space (return air). The chilled water will then be returned to the chiller will it will give up its heat to the evaporators heat exchanger as part of the refrigeration cycle.

Chilled Water Circuit - Heat Absorption Cycle — Chilled Water Circuit – Heat Absorption Cycle

Heat Rejection Cycle

Now that we have absorbed the heat from the building space and any ventilation air, we’ll need to toss this heat out of the building. The chillers refrigeration cycle will transfer the heat from the evaporator to the compressor where it will be increased in pressure and temperature.

After the compressor the refrigerant is now in the high-side of the refrigerant circuit where it enters the condenser. The condenser will rejects this heat into the air or water depending on the type of chiller (air-cooled vs water-cooled).

Heat Rejection Cycle Water-Cooled Chiller

Heat Rejection Air-Cooled vs Water-Cooled Chillers

As previously discussed water-cooled chillers use some form of cooling tower to reject the heat, see our video on “How Cooling Towers Work”. The high side refrigerant gas that enters the water-cooled chillers condenser will change from a refrigerant gas to a liquid as it gives up its heat to the condenser water circulating through the shell and tube heat exchanger. That heat is taken in the condenser water to the cooling tower where it is transferred to the ambient air passing over the tower fill.

An air-cooled chiller is a mostly self-contained unit, although there are version of the air-cooled system that can have separated sections, the most common is a one-piece unit.

Space Requirements

Of course one of the difference between the two style of chillers is that an air-cooled chiller will be located outside, while a water-cooled chiller is almost always located indoors. This will require real estate for either style, whether that is outside or inside. In addition the water-cooled chiller will require a cooling tower that is often located on the roof or somewhere on grade. Depending on the size of this equipment, they can become very heavy requiring structurally engineered supports, especially roof mounted cooling towers and chillers.

Water-Cooled Chiller Basement Level - Ground Floor Cooling Tower — Water-Cooled Chiller Basement Level – Ground Floor Cooling Tower

Water-Cooled Chiller with Ground Mounted Cooling Tower

Above we show a Water-Cooled chiller located in the basement of an office building with the Cooling Tower on ground level. Chiller feeds the air handlers on each floor with chilled water, and then the fan of the air handler blows cold air into the occupied spaces.

Water-Cooled Chiller Roof-mounted Cooling Tower

Water-Cooled Chiller with Roof Mounted Cooling Tower

In the above image we show the Water-Cooled Chiller in a ground level mechanical room with a cooling tower on the roof. The cooling tower is going to require that the roof be reinforced to handle the additional weight of the tower.

Air-Cooled Chiller Ground Mounted

As shown in the above image an Air-Cooled Chiller has a much easier layout without the requirement for a cooling tower to reject the heat.

Main Components of a Chiller

The first component is the compressor which provides the energy to move the refrigerant around the refrigerant circuit.

The second component is the evaporator where heat is absorbed from the building and the water is cooled down to be used within the building to cool the space.

The third component is the condenser which rejects the heat from the building into the water going to a cooling tower or in an air-cooled chiller the heat is rejected to the outdoor ambient air.

The expansion valve or metering device, is called by various names but it functions as the gate keeper between the high-side (Condenser) and low-side (Evaporator), and is the forth component. This valve meters the amount of refrigerant that can pass from the high-side to the low-side based on the demand for cooling. More cooling required will cause the expansion valve to allow more refrigerant to pass through it, going from the high-side to the low-side of the system.

Water-Cooled Chiller

When looking at any water-cooled chiller there are several ways to spot which of the two shell and tube heat exchangers is the evaporator vs the condenser, as they both physically look the same. The evaporator should have insulation on it to avoid absorbing heat from the surrounding mechanical room. The condenser doesn’t need insulation. Also, the evaporator should have a short stub of pipe coming off of it into the center of the compressor.

The condenser doesn’t need insulation and you should notice that the compressor discharges off its periphery into the condenser with a short stub of pipe.

The expansion valve or metering device is often hidden underneath, but will be located between the two heat exchangers.

Air-Cooled Chillers

These are easy to identify as they are most always located outside and you’ll see the fans located on them, mostly on the top an using axial fans that induce air over the condenser coils. These chillers have all the same components as a water-cooled chiller except a shell and tube type condenser isn’t used. The Air-cooled chillers use an condenser exposed coil with ambient air induced or blown over it to reject the heat.

Summary

You may be thinking, if Air-Cooled chillers only require a single piece of equipment as opposed to water-cooled chillers that require a cooling tower of some sort, than why don’t all mechanical engineers specify only Air-Cooled Chillers. Several reasons are that air-cooled chillers aren’t as efficient as water-cooled chillers and some codes restrict the total tonnage of air-cooled chillers that can be used at one facility.

When looking at any piece of air conditioning equipment or chiller, look to identify these four components. The difference between water-cooled and air-cooled chillers are in how the heat is rejected from the system. In a water-cooled system, water is used as the method for heat rejection, while air-cooled chillers use air as the heat rejection method, hence the naming.

If you haven’t seen our video on refrigerant circuit, then be sure to watch that for a more in-depth explanation of the refrigeration cycle.

New Refrigerant Codes and Standards

MEP Academy Instructor

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December 22, 2021

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Overview

The push for lower global warming potential (GWP) refrigerants is causing a shift in the refrigerants that will be used in future equipment. The recently passed legislation of the American Innovation and Manufacturing (AIM) Act, which was part of the December 2020 COVID stimulus bill, has given the EPA authority to regulate refrigerants based on GWP.

The proposed new regulations and standards will mean additional training for technicians doing the installations as the flammability of the proposed replacement refrigerants are slightly higher than what is currently being used.

Refrigerant Codes and Standards - Montreal Protocol - Kigali Amendment - CARB - EPA — Refrigerant Codes and Standards – Montreal Protocol – Kigali Amendment – CARB – EPA

For those in California, one of the more progressive states for energy and the environment, these phaseout dates may come faster than a federal mandate. The California Air Resources Board (CARB) is looking at January 1, 2025 for the implementation of a maximum GWP of 750, which would eliminate the widely used R-410A in most unitary and split systems.

EPA Aim Act vs CARB - Reduction of R-410A Refrigerant — EPA Aim Act vs CARB – Reduction of R-410A Refrigerant

Refrigerant Safety Codes and Standards

The use of these new A2L refrigerants will require that the building codes of state, cities and municipalities be updated before the wide spread adoption. The majority of these requirements will be written into UL 60335-2-40 3^rd edition, ASHRAE 34 and ASHRAE 15 – 2019. (ASHRAE 15.2P – Residential).

The new ASHRAE 15.2P for residential application is set to be ready for the January 1, 2025 transition.

Mechanical ASHRAE 34

ASHRAE 34 classifies refrigerants for safety. The first letter as shown below represents the toxicity class of the refrigerant. The second number/letter identifies flammability.

ASHRAE 34 - Refrigerant Safety - Toxicity and Flammability — ASHRAE 34 – Refrigerant Safety – Toxicity and Flammability

There are two classes of toxicity, class A or B, with B considered more toxic.

Flammability has four classes (1, 2L, 2, or 3), with 3 being the highest flammability.

ASHRAE 15

Those familiar with ASHRAE 15 for commercial projects are aware of the requirements, but what about the new proposed ASHRAE 15.2P for residential projects. ASHRAE Standard 15 is a Safety Standard for Refrigeration Systems in the event of a catastrophic leak. ASHRAE is getting close to finalizing the standard that will apply to residential buildings (ASHRAE 15.2P), but there are still the state and local code authorities that will need the standard adopted into their code, during their code cycles.

The desire for ASHRAE is to have a model standard (ASHRAE 15.2P) adopted by building codes, thereby giving guidance on the safe application of the use of A2L refrigerants in residential settings.

Checkout Refrigerants here

The slight increase in flammability with the proposed use of A2L refrigerants like R32 & R454B will require additional safety measures to ensure that a catastrophic leak will not cause harm to the occupants. This hazard can be mitigated by making sure that the amount of refrigerant charge is limited based on floor area or that some form of ventilation is activated when a leak is detected.

Why hasn’t ASHRAE standard 15 applied to residential properties before? The classification (A1) by ASHRAE Standard 34 of the refrigerants currently used in residential properties were considered safe if a leak occurred within the occupied space. The assumption was that the acute toxicity exposure limit would not be exceeded in a catastrophic leak. The proposed new classification of refrigerants (A2L) to be used in residential properties are considered slightly flammable to a greater extent.

The move to the A2L refrigerants is driven by the desire to have a lower global warming potential (GWP) refrigerant.

So what will be some of the new requirements? Since the new A2L refrigerants are slightly more flammable, there needs to be a way to mitigate any chance of a fire.

ASHRAE Standard 15.2P

This standard will cover the safe design and installation of residential refrigeration systems. Historically residential refrigerant system were considered safe because they use class A1 refrigerants and the level of acute toxic exposure wouldn’t be exceeded in a catastrophic leak.

The push for lower global warming potential (GWP) refrigerants has manufacturers proposing refrigerants classified as A2L (Low toxicity & Low flammability), such as R32 or R454-B. Currently the widely used R410A in packaged and split systems is classified as an A1 (Low Toxicity & No Flammability) refrigerant. This increase in flammability is what has generated the additional concern and need for additional safety measure.

Refrigerant Tool Compatibility

Can you use the same tools that you have been using for R-22 and R-410A with the newer refrigerants?

Changing from R22 to R32

R32 operates at a higher pressure than R22, and R32 uses a different type of oil. The oil from the R22 system could cause sludge or other issues, therefore all the tools used for your R22 systems should not be used for R32, such as gauge manifolds and hoses. Have a dedicated manifold and hoses just for your R32 systems.

Changing from R410A to R32

Since R32 uses has similar operating pressures and oil properties as R410A, so the use of separate manifolds and hoses isn’t required if so stated by the tool manufacture.

So, you won’t be able to replace just one component of an R-22 system with that of an R-32. If you replace an R-22 Outdoor unit, you’ll need to replace the coil, but you maybe able to use the refrigerant piping.

Refrigerant Tool Compatibility between R22 R410A and R32

*1: R22 type can be used for R32 & R410A by changing the work process.
*2: Dimension of width across flats of flare nut is different between R32 & R410A and R22 (4/8″ & 5/8″ only. Other flare nuts can be shared)
*3: When using an R22 type for R32 & R410A, use with a reverse flow preventive adapter.
*4: HFC recovery systems can be shared if they have been certified by the manufacturers to be supporting the relevant HFC’s.
*5: Even if a detector supports R22, if the detector does not support HFC (R32, R410A), it cannot be shared. Always check with the tooling manufacturer.
*6: Sharable when temperature is recalculated

Additional Safety Measures

These additional safety protocols will fall partly on the installing technician and contractor. This will include additional safety training and site analysis for spaces that maybe too small to handle a catastrophic leak and maintain the maximum exposure limit of the refrigerant. One of the questions becomes, is a refrigerant leak detection system required?

Also keeping track of sources R410A before the 40% reduction occurs in 2024 will be important for servicing existing equipment.

The equipment manufactures need to provide clear installation instructions based on the safety parameters required of their choice refrigerant and the size or quantity of the refrigerant. But how does this work with a split system, where you won’t know the total volume of refrigerant until all the piping has been installed.

Additional Requirements for Technicians

Will the service technicians be required to calculate the total refrigerant in the system to ensure it doesn’t exceed the allowable limits? Will the service technicians be required to calculate the allowable area of the spaces served?

It has been mentioned that there could be lookup tables to help the technician determine the allowable floor area based on the refrigerant charge as shown in this chart for Daikin European model of their wall-mounted unit using R-32 refrigerant.

Daikin Wall Mounted Unit using R-32 Refrigerant in Europe

In the example shown in the chart above, if you have 2 kg (4.4 Lbs) of R32 in the system, then the minimum floor area is shown to be 4 m2 (43 Ft2).

You won’t just be able to change out an old outdoor unit that was using R410A without also replacing the indoor coil, as both must be UL rated for the new refrigerant class A2L. It appears that you will be able to use the existing piping but will have to ensure through a more rigorous testing protocol that there isn’t any existing leaks.

There is still plenty to be worked out before we know exactly what the installing technicians will be required to do in addition to what was the standard protocol using R22 or R410A. How much time will this add to an installation, or how much training will be involved, or for that matter, record keeping?

Refrigerant Safety Training

There is training currently available for flammable refrigerants that you can find provided by the Air Conditioning Contractors of America (ACCA) and by the North American Technician Excellence (NATE) in addition to other trainers.

UL Standards

Here are some for the highlights for the updated UL standard;

Products using flammable refrigerants are required to be constructed so that any leaked refrigerant will not flow or stagnate near ignition sources such as electrical components.
Enhanced requirements are applied to the refrigerant tubing, joints and fittings on equipment having a flammable refrigerant, to reduce potential sources of leaks by minimizing the number of joints and additional protection from physical damage.
Any products using a flammable refrigerant other than a 2L must be factory sealed, factory charged single package units and service ports are not permitted.
No hot surfaces greater than 700-degree C are allowed in an area that may be exposed to leakage of flammable refrigerants.

In addition, there will be a limit to the amount of refrigerant in a system based on the Lower Flammable Limit (LFL) of the refrigerant being used in relationship to the floor area it serves. This is not a problem with small system, but as the Refrigerant system gets larger there will be a corresponding need to ensure that any of the rooms served are large enough to handle a catastrophic leak and stay within the LFL limits.

If you exceed those limits than you’ll need some form of mitigation strategy, like a continuously circulating supply fan to help dilute the leak or you’ll need a leak detection system.

Using a leak detection system will activate several key functions to ensure a safe environment. The leak detector when activated can ensure that the supply fan is locked to run continuously to dilute the space while at the same time turning off the compressor to avoid pushing more refrigerant into the space. Also, close any safety shutoff valves in the refrigerant system to stop the bleeding of refrigerant into the space while opening zone dampers to allow more air circulation. Refrigerant systems located within a closet or whose volume of refrigerant is large may require natural and/or mechanical ventilation.

Refrigerant Leak Detection Systems

When are refrigerant detection systems required? What are the defining characteristics of the HVAC refrigerant system that mandate you install a refrigerant detector? The refrigerant detector needs to indicate the type of refrigerant used.

The refrigerant detector can’t have an adjustable set point to initiate mitigation action. You can see why this could be a problem if it was adjustable. If allowed the ability to adjust, then it’s possible the setting would be set higher than the allowable safe limits.

For spaces that exceed the allowable quantity of refrigerant for the floor area served a refrigerant leak detector that senses a loss of pressure in the refrigerant circuit would be required.

If the leak detector senses a loss of pressure than the controls would activate the supply fan to provide dilution air to lessen the accumulation of concentrated amounts of refrigerant. The HVAC equipment is not allowed to have an internal ignition source due to the risk of flammability of the class A2L refrigerants, per UL 60335-2-40.

Requirements for Refrigerant Leak Detection Systems per UL

Indicating type detectors are required to be factory installed by the manufacturer with sensors optimally located to detect any leaks.
Refrigerant leak detector sensor set point is factory set and sealed with no field adjustment permitted. Routine factory inspections are conducted by UL as part of the listing requirements. Detector markings identify the manufacturer and refrigerants used.
The leak detection system is required to activate at a maximum concentration of < 25% of the LFL of the refrigerant being used in the equipment. This 4-times safety factor helps ensure flammable concentrations are not reached.
Detectors turn on available mitigation devices such as circulation fans.
Self-test protocols run every hour to ensure proper operation and function. In the event of detector failure, the circulation fans activate and maintain a required airflow to prevent flammable concentrations from forming. This fail-safe mode is maintained until the detector is replaced.
The sensor shall not be subject to poisoning due to common household and workplace contaminants that shall not damage the sensor or produce false alarms or nuisance trips per Annex LL of UL 60335-2-40.

Various Refrigerant leak detectors are currently being evaluated by the Air-Conditioning, Heating and Refrigeration Technology Institute (AHRTI). The Institute is assessing the capabilities of currently available refrigerant detectors to meet the response time required by the safety standards, with setpoint(s) determined in a manner to meet the safety standard considering related issues such as upper detection limits, accuracy and calibration, drift over time, sensitivity to environmental conditions (temperature, pressure, humidity and vibration).

Residential installation was simple before this quickly arriving change that will require a safety review of your companies handling and installation practices for these refrigerants.

Some equipment may come with a designated minimum allowed room area right on the equipment label, such as with spot coolers or room air conditioners.

HVAC Equipment Certification

Not to confuse the issue but HVAC equipment manufacturers (US & Canada) will need to certify their equipment to meet the revised addition of UL 60335-2-40, the standard that covers electric heat pumps, air conditioners and dehumidifiers.

System Charge

The allowable amount of refrigerant in the system will depend on the LFL and the floor area of the room that is served by the system.

Resources:

EPA Kigali Ratification

The Aim Act

UL Refrigerant Detector Requirements

UL Safety Standards for AC

Refrigerant Management Templates

EPA SNAP

Top 12 Best Construction Bidding Websites

MEP Academy Instructor

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December 8, 2021

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Top 12 Best Construction Bidding Websites

As a follow up to our article on the ‘Top 3 Things to Look for when Bidding a Project’, this article will cover where to find the Top 12 Construction Bidding Websites.

The following websites will help you locate projects to bid that might fit your target market.

Finding construction projects to bid from online sources can be frustrating as there are so many options. Determining which ones best fit your needs will take some effort, so we have assembled a partial list of some of the top construction bidding websites which includes some Government Public work projects.

All of these sites are for commercial construction projects, if you’re looking for residential work then you can use a site like Angie’s Home Advisor.

The below websites are some of the best construction websites for bidding private or public commercial construction projects. The websites are listed in no special order.

The listing on these websites can provide notice of projects in various states of development from design through post-bid award. Most of these websites allow for search of a project by location, but others also allow for searching of owners, engineers, architects and others involved in the construction process.

Top 12 Best Construction Bidding Websites

1 – CMD – Construction Market Data

CMD - Construction Market Data for Bidding on Construction Projects — CMD – Construction Market Data for Bidding on Construction Projects

CMD states that they have over 184,000 projects bidding and another 85,000 in the planning stages, in addition to 5,000 project updates daily. Also, 90% of all bidding projects have documents attached 14 days before bid day.

You can search projects by location (U.S. and Canada), building type, phase of project and industry. They allow you to search the project documents including plans and specifications for targeted keywords.

CMD Website -> Construction Market Data

2 – Dodge Data & Analytics

Dodge Data and Analytics Construction Bidding Service

Dodge Data & Analytics has been around in some form for over 100 years helping the construction industry better understand the construction market. Dodge is a widely known industry player and holds several assets in their portfolio including the Blue Book, an industry source for the commercial construction industry and the Sweets Catalogues for Architects, designers, contractors and owners. They have a whole solution of products for the construction industry, one of which is “Construction Leads”.

Dodge Construction Leads allows you to see who else has downloaded drawings for a particular project, allowing you to gauge the competition and interest.

Search North American projects for access to plans and specifications from your office or mobile device. Receive email alerts based on the project location, stage of development, project value or building type. Dodge also allows you to track your results and provides sales pipeline reports that measure sales activity and ROI that can be exported to Excel or PDF.

Dodge Data & Analytics Website -> Dodge Data

3 – Government Bids.com

Government Bids .com provides access to Government Construction Projects

This is a source for bidding Government projects. The GovernementBids.com website allows you to search based on location and trade served.

For the State and Local subscription you get access to bids, RFP’s and RFQ’s from over 80,000 agencies including state governments, cities, municipalities and counties as well as special district agencies such as: Police, Fire protection and correctional departments, Hospital and health facilities, School Districts and Libraries, Water and Waste Management, Parks & Recreation, Utilities, Airports, Public Transportation and Toll Roads.

For adding the Federal Agency to your subscription you get access to Bids, RFP’s and RFI’s from federal government agencies including: Department of defense, Homeland Security and General Services Administration (GSA).

Adding “Advanced” to your subscription gets you access to see upcoming opportunities before they become bids.

Adding “Awards” to your subscription allows you to see the winning bidder and the amounts on bids awarded.

Prices for their service is as follows as of the date of this article and is based on signing up for a yearly subscription:

State & Local Projects: $44/Month
Federal, State & Local Projects: $73/Month
Advanced: $87/Month
Awards and Advanced: $131/Month

Government Bids Website -> Government Bids

4 – iSqFt

The iSqFt website claims that you can get promoted to over 1,500 GC’s in their network which spans the U.S. and Canada and includes both public and private projects. They provide access to projects in development and that are currently bidding, along with access to additional general contractors bidding on the project, not just the GC that invited you. They claim that they have a 91% attachment rate for construction documents and an average bid window of 3 weeks.

They state that you will increase by 5x the amount of Bid Invitations you’ll receive by creating new GC relationships. They provide a complete list of GC’s for each project along with their contact information.

Search by location and type of installation. You can also search for keywords in the documents. Receive alerts for projects updates, new bidders added and addenda’s. Training is provided free with a subscription.

iSqFt also has the added feature of allowing you to do digital takeoffs for an additional service fee.

iSqFt Website -> iSqFt

5 – Planhub

Planhub allows you to search projects by location, construction type, project type, timeline, and more. You can submit bids to multiple general contractors on a project. Planhub has a centralized dashboard where you can see all your project info in one view – bids, calendar, instant messaging, and more. Cloud based documentation that allows you to view or download project blueprints and project documents.

Planhub’s pricing plan is based on an annual or quarterly basis and the distance or mile radius you want included in your plan.

Planhub Subcontractor Pricing (Annual)

Basic: Free Trial
Premier (50 Mile Radius): $1,199/Year
Premier (100 Mile Radius): $1,299/Year
Premier (150 Mile Radius): $1,499/Year
Premier (200 Mile Radius): $1,699/Year
Premier (500 Mile Radius): $1,999/Year
Premier (1,000 Mile Radius): $2,899/Year

Planhub Website -> Planhub

6 – Construction Wire (BCI Build Central)

ConstructionWire offers a free 7-day trial for leads on most private new construction projects in the planning, bidding, and pre-construction stages.

You can search by location, stage of development, project type, project value, company name, company type (owner, developer, tenant, Architect, Engineer, GC, Property Manager) and people.

Pricing starts at:

Regional Portal (Up to 3 States): $250/Month
National Portal (All 50 States): Price based on your Company Size

BCI Build Central Website – > Build Central

7 – BidClerk

Bidclerk – Public and Private Construction Projects

BidClerk provides both public and private projects in the United States and Canada. Information is available on projects in the early design phase to post-bid. You can download project data from BidClerk in PDF or CSV format and, build your own database of contacts for architects, engineers and contractors. BidClerk is accessible on your mobile devices. Automatic email notifications when any of your projects receives an update.

Search Features – Location (State, City), Project Type (Office, Schools, etc), Status (Design, Bidding, Awarded …) Sector (Private, Public – Fed/State/City/County), Project Value

Bidclerk Website -> Bidclerk

8 – BidNet

BidNet gathers federal, state and local government RFP’s from across the United States, and delivers new contract opportunities to you every day. BidNet’s Advance Notification feature alerts you months before a term contract in your industry expires, providing an opportunity to influence the creation of the next proposal.

BidNet allows you to search by State, Industry (Construction) and your Trade.

Pricing based on three levels of service

State & Local: “Request Pricing”
Federal, State & Local: “Request Pricing”
Advance Plus: “Request Pricing”

BidNet Website -> BidNet

9 – Construction Bid Source

Construction Bid Source for bidding construction projects — Construction Bid Source

CBS is one of the few websites that list their fees upfront. Prices range from free for limited access or full membership for $39.95/month. They have been in service since 1992. Less fields to search for projects, search seems restricted to location (State and County) and bid date range. Not as robust as other websites but for the cost it may be worth a try.

Construction Bid Source Website -> Construction Bid Source

10 – BidCentral (Canada)

BidCentral - Canadian Construction Projects — BidCentral – Canadian Construction Projects

BidCentral is based out of British Columbia for all those of you that want to chase work in western Canada, Vancouver area. The database provides access to private and public projects with auto notification when new projects are posted.

Their Pricing is as follows;

Browse Free (View Projects): $0/Month
Premium Monthly: $79/Month

BidCentral Website -> BidCentral

11 – Biddingo.com (Canada)

Biddingo.com is an online portal that connects suppliers providing various goods and services to buyers from the Provincial, Municipal, Education, Crown Corporation, Housing, Construction and Healthcare sectors and Private companies from across Canada.

Buyers, public and private alike, throughout Canada advertise RFPs, RFQs, RFIs, etc. and distribute their documents on Biddingo.com daily. They have access to detailed reports such as invitation lists, document taker’s lists, mandatory site meetings, amendment notices, bid results, awarded contracts, etc. Biddingo.com assists buyers with fulfilling their purchasing requirements.

It appears to have very limited search features, basically by category.

Pricing: $250/Year annual subscription
30-Day free Trial

Biddingo Website -> Biddingo

12 – MERX (Canada)

MERX is another Canadian company providing public and private projects, plus an option to join the U.S. Bidding Opportunities list. They have the eBid SubmissionSecure bidding process made easier and more efficient with Electronic Bid Submission feature.

Searching criteria appears to be based on location (Canada or US), entity type (Public – Federal, State & Local) or private construction work, Region (State), type (Open Bids, Closed Bids & Awards)

Pricing is as follows in Canadian Dollars:

Basic Plan: $60/Solicitation
Local (One Province): $25/Month
Regional (One Region): $40/Month
National (All of Canada): $75/Month

The following is included in all plans except the Basic plan:

Unlimited document downloads for Canadian public and private opportunities
Unlimited electronic bid submissions
Access to the Document Request List to identify partnering opportunities
All plans include the Northwest Territories, Yukon and Nunavut

MERX Website -> Merx

All the information in this article for Construction Bidding websites were retrieved in December 2021. Check Data providers website for the most recent pricing and features of their services.

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Resources:

Top 12 Best Construction Bidding Websites

1 – CMD – Construction Market Data

2 – Dodge Data & Analytics

3 – Government Bids.com

4 – iSqFt

5 – Planhub

6 – Construction Wire (BCI Build Central)

7 – BidClerk

8 – BidNet

9 – Construction Bid Source

10 – BidCentral (Canada)

11 – Biddingo.com (Canada)

12 – MERX (Canada)

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