We’ll discuss an adiabatic fluid cooler, an air-cooled condenser with water spray, and an air-cooled condenser using adiabatic cooling.Â
Air-Cooled Condenser with Water Spray and Adiabatic Fluid Coolers
An adiabatic fluid cooler is a device used for cooling fluids, typically water or a water-glycol mixture, while an adiabatic air-cooled condenser is used to cool a refrigerant based systems. These systems are used in industrial and commercial applications. They operate based on the principle of evaporative cooling combined with a heat exchanger.
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How Adiabatic Cooling Works:
The hot water in an adiabatic fluid cooler flows into the heat exchanger. The heat exchanger consists of coils of tubes surrounded by fins. These tubes are in contact with the hot water. As the hot water flows through them, heat is transferred to the coil surface and fins of the heat exchanger. The heat exchanger can be provided with an epoxy coating to increase corrosion resistance without sacrificing unit capacity.
Adiabatic Fluid Cooler
Water is sprayed or circulated over a pre-cooling pad, to keep it fully wet. This fully wetted medium sits in front of the heat exchanger, and is often made of corrugated cellulose, synthetic material, or fibrous pad. Cool, dry ambient air is drawn through the wetted medium by a fan located on top of the unit, the air becomes humidified as some of the water evaporates into the air, absorbing heat from the surrounding air in the process.
The evaporation of water from the wetted medium extracts heat from the surrounding air, reducing the ambient dry bulb temperature within proximity to the wet bulb temperature. This cooled air then passes over the surface of the heat exchanger where it absorbs heat from the hot fluid inside the tubes and on the surface of the fins. The heat is then discharged to the atmosphere by fans sitting at the top of the unit. As a result, the hot fluid inside the tubes loses heat to the cooled air through the heat exchanger.
The cooled fluid exits the adiabatic fluid cooler and can be recirculated back into the system it’s cooling, such as an HVAC system or industrial process. This effectively transfers the absorbed heat to the adiabatic fluid cooler and then to the atmosphere.
Variable Speed Fans
The variable speed fans inside the adiabatic fluid cooler draws air through the wetted medium and across the heat exchanger to facilitate the cooling process. The speed of the fan(s) can be adjusted to control the cooling capacity of the unit.
By combining evaporative cooling with a traditional heat exchanger, adiabatic fluid coolers can achieve significant energy savings compared to conventional air-cooled heat exchangers, especially in hot and dry climates where evaporative cooling is particularly effective.
Reduces Water Consumption
The Adiabatic fluid cooler can eliminate or significantly reduce water consumption compared to the traditional evaporative systems. They can be operated without water until ambient conditions require additional capacity to meet demand. This reduces water consumption and the cost to treat and dispose of water. There is no water basin to hold water or that can gather dirt and debris. This is because the water passes through once and isn’t recirculated so there is no need for a recirculation pump.
Adiabatic Condenser
The adiabatic version of the air-cooled condenser uses a fully wetted medium that sits in front of the heat exchanger coil. The air flow and heat transfer process is the same as previously discussed using the adiabatic fluid cooler for water, except now it’s refrigerant as the medium.
Air-Cooled Condenser with Water Spray
For the air-cooled condenser, the refrigerant vapor enters the condenser and leaves as high-side refrigerant liquid. The system will turn on the water spray when it fails to maintain the refrigerant condensing pressure.
Refrigerant Condenser Cooled by a Water Spray System
The water is sprayed outward away from the coil into the air stream. The air is pulled across the coil by the variable speed fans. The heat from the hot refrigerant is transferred to this cooler air causing the refrigerant to condense into liquid. The condenser will conserve water by running dry and only spraying water when ambient conditions require a lower entering temperature. That’s why these systems are recommended for high ambient dry bulb climates or high temperature applications.
What is adiabatic Cooling?
Adiabatic fluid coolers or condensers operate like dry cooling systems, except they have water running over pre-cooling pads. The air is drawn through the pads depressing the ambient dry bulb temperature of the incoming air. The depressed or reduced dry bulb temperature provides for greater system heat rejection than a dry system.
HVAC School for Technicians. In this article we’ll cover what you can expect to be paid as an Air Conditioning and Refrigeration Technician, the education required, and what you can be expected to do while at work.
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Air Conditioning and Heating systems play a crucial role in controlling the temperature, humidity, and air quality within residential, commercial, and industrial buildings. Essential items such as food and medicine rely on refrigeration to prevent spoiling. Skilled technicians are responsible for the repair, maintenance, and installation of heating, air conditioning, and refrigeration systems.
Average Pay for a HVACR Technician
How much money can you make as an Air Conditioning and Refrigeration Technician?
Air Conditioning and Refrigeration Technicians get paid anywhere from $37,270 and less for the bottom 10% of workers, to more than $84,250 per year for the top 10% of earners according to the Bureau of Labor Statistics for 2023. The median wage was $57,300 in May 2023.Â
The Average Pay for an HVACR Technician for the year 2023
Most of the HVACR technicians work at full time positions, which may require evening and weekend hours. During peak seasons for heating or cooling, HVACR technicians can be requested to work overtime or irregular hours to help customer get their systems up and running after they breakdown. Obviously working overtime will increase your hourly pay.
Current Job Opportunities
According to the Bureau of Labor Statistics, the Employment of heating, air conditioning, and refrigeration mechanics and installers is projected to grow 6 percent from 2022 to 2032, faster than the average for all occupations.
About 37,700 openings for heating, air conditioning, and refrigeration mechanics and installers are projected each year, on average, over the decade. Many of those openings are expected to result from the need to replace workers who transfer to different occupations or exit the labor force, such as to retire.
EDUCATION
While a high school diploma or equivalent may be the minimum requirement for many entry-level positions, obtaining formal education through a vocational school, community college, or technical institute can provide a solid foundation. Some of these vocational programs even take individuals lacking a high school diploma. Look for programs specifically focused on HVAC (heating, ventilation, and air conditioning) or refrigeration technology.
Training Programs
Consider enrolling in an apprenticeship or training program offered by trade associations, Unions, Technical Schools, or HVAC companies. These programs often combine classroom instruction with hands-on experience under the guidance of experienced technicians. If accepted into a Union apprenticeship program you’ll be paid while learning.
HVAC Service Technician fixing a Fan
Certification
Although not always mandatory, obtaining certification can enhance your credibility and job prospects. A Certificate of Achievement can be secured from an HVACR technical school in 2 years or less. This can shorten the period from entering school to getting a full-time job. After your first semester in a technical school, you could seek a part-time apprenticeship job with a local HVAC contractor.
The most widely recognized certification for HVAC technicians in the United States is offered by North American Technician Excellence (NATE). Other certifications may be available depending on your location and specialization.
Licensing
In some jurisdictions, HVAC technicians are required to obtain a license to work independently. This won’t stop you from working for others. Requirements vary by state or country, so be sure to research the specific licensing regulations in your area. States like California requires a contractor’s license to open your own company and require prior work experience.
Skills Development
Develop a strong understanding of heating, ventilation, air conditioning, and refrigeration systems, as well as electrical and mechanical principles. Good problem-solving skills, attention to detail, and the ability to work independently are also important.
Experience
Gain practical experience by working as an apprentice or entry-level technician under the supervision of experienced professionals. This will allow you to apply theoretical knowledge in real-world settings and develop valuable troubleshooting skills.
Continuing Education
Stay updated on advances in HVAC technology and industry regulations through continuing education courses, workshops, and seminars. This will ensure that your skills remain relevant and competitive in the field.
By following these steps and continually honing your skills, you can become a competent and successful HVACR technician.
The Work of an Air Conditioning & Refrigeration Technician
Air conditioning and refrigeration technicians, install, maintain, and repair, heating, ventilation, air conditioning, and refrigeration systems. These systems are found in residential, commercial, and industrial buildings.Â
HVAC Technicians working on Rooftop HVAC Units
This could include work on small residential systems such as split systems or packaged units. Also large chilled water plant equipment such as air-cooled and water-cooled chillers. Chillers provide cold water that gets pumped throughout the building. Or you could be working on commercial boilers that provide heating. There are various additional commercial systems that add an extra layer of complexity to the job.
Their responsibilities typically include:
Installation
Installing new HVACR systems, including air conditioners, furnaces, heat pumps, Variable Refrigerant Flow Systems, refrigeration units, and ventilation systems. Installing these systems in accordance to specifications and building codes.
Installation of new HVAC Units
This includes learning how to cut and prepare copper tubing ends, including flaring, swaging, and brazing.
Maintenance
Performing routine maintenance tasks such as cleaning coils, replacing filters, checking refrigerant levels, lubricating moving parts, and inspecting electrical connections. This ensures systems operate efficiently and safely.
Repair
Diagnosing and troubleshooting problems with HVACR systems, including issues with components such as compressors, motors, thermostats, boilers, and pumps. This includes making the necessary repairs to restore functionality.
Refrigerant Handling
Handling refrigerants safely and in compliance with environmental regulations, including recovering, recycling, and disposing of refrigerants according to industry standards.
Customer Service
Interacting with customers to understand their heating and cooling needs. Providing recommendations for system upgrades or replacements. Ensuring customer satisfaction with the quality of service provided.
Safety Compliance
Adhering to safety protocols and regulations to minimize risks of injury or property damage during installation, maintenance, and repair activities.
Overall, air conditioning and refrigeration technicians play a crucial role in maintaining comfortable and efficient indoor environments, by ensuring that HVACR systems operate effectively and reliably.
Where HVACR Technicians Work
Air conditioning and refrigeration technicians work in a variety of environments, depending on the specific job and industry. Here are some common work environments for HVACR technicians:
Residential Settings
Technicians may work in homes, apartments, and condominiums to install, repair, and maintain heating, ventilation, air conditioning, and refrigeration systems for individual homeowners or property management companies.
Commercial Buildings
HVACR technicians often work in commercial settings such as office buildings, retail stores, restaurants, and hotels. They may install and service larger HVACR systems to provide climate control for occupants and ensure comfort and productivity.
Industrial Facilities
In industrial settings such as factories, warehouses, and manufacturing plants, technicians may install and maintain specialized HVACR systems to regulate temperature and humidity levels for equipment operation and product storage.
Healthcare Facilities
Hospitals, clinics, and medical laboratories require precise temperature and humidity control to maintain a sterile environment and protect sensitive medical equipment. HVACR technicians may work in these facilities to install and service specialized HVACR systems.
Educational Institutions
Schools, colleges, and universities rely on HVACR systems to create comfortable learning environments for students and faculty. Technicians may be employed by educational institutions or contracted to provide HVACR services.
Government Buildings
HVACR technicians may work in government buildings such as courthouses, libraries, and municipal offices to maintain climate control systems and ensure the comfort and safety of employees and visitors.
Construction Sites
During new construction or renovation projects, HVACR technicians may work on construction sites to install piping. This includes installing HVACR equipment according to building plans and specifications.
Outdoors
Some tasks, such as HVACR system inspections, maintenance, and repairs, may require technicians to work outdoors, especially when servicing rooftop units or equipment located in outdoor enclosures.
Overall, air conditioning and refrigeration technicians can expect to work in a variety of indoor and outdoor environments. They will encounter different conditions and challenges depending on the specific job and industry. They must be prepared to adapt to different work settings and follow safety protocols. This is to ensure their well-being, and the efficient operation of HVACR systems.
How many CFM per Ton should you consider for an HVAC unit? How is CFM per Ton figured? Have you ever heard of anyone throwing around CFM per Ton numbers like 400 CFM per Ton? What do these numbers really mean? Is it better to have more or less CFM per Ton? We’ll cover the conditions that impact CFM per Ton on various air conditioning performance charts and how you can determine the CFM per Ton.
Affects of Outside Ambient Temperature on Capacity
We’ll first look at the Outdoor Ambient Temperature and how it effects the capacity of a 6-ton split system air conditioner. Here we have a chart for the 6-ton air conditioner with the 95 F highlighted in pink, and the AHRI dry bulb temperature of 80 F highlighted in blue under each outdoor temperature, and the AHRI wet bulb temperature of 67 F and the intersecting columns and rows for these temperatures.
We show the CFM settings for this chart at 2400 which corresponds to 400 CFM per Nominal Ton. The 2400 CFM row represents 400 CFM per Ton as follows 6 Tons x 400 CFM/Ton = 2,400 CFM.
TC = Total Capacity in MBH
MBH = btu’s in 1000’s
SHC = Sensible Heat Capacity
If we follow the 2400 cfm row at 67 F wet bulb temperature, you’ll notice that the total capacity keeps decreasing as the outdoor ambient temperature gets warmer. For instance, at 85 F ambient the AC unit provides 74.1 MBH of cooling, and at 105 F ambient the total capacity drops to 67.7 MBH.
How many CFM per Ton based on Outside Ambient Temperatures
Fact #1Â As the Outdoor Ambient Temperature goes up, Total AC Capacity goes Down.
Affects of Outside Air Temp on CFM per Ton
If we plot these values on a chart, we can see how CFM/Ton changes with the Outside Ambient Temperature. With the air conditioner providing a constant air volume of 2400 CFM and the Capacity decreasing as the Outdoor Ambient Increases, this implies that the same amount of CFM is provided for less capacity (Tons) at higher outdoor temperatures, hence the AC unit goes from 389 CFM/Ton to 478 CFM/Ton.Â
So, is more CFM/Ton a good thing? In this case no, as it reflects that more air is required to be delivered for every ton of air conditioning. This is due to the air conditioner having to work harder at the elevated temperature. Most Air Conditioners are derated in capacity when the outdoor air temperature exceeds 95 F.
Fact #2 As the Outdoor Ambient Temperature goes up, the CFM/Ton increases.
Affects of Wet Bulb Temperature on CFM per Ton
When the indoor wet bulb temperature increases, the CFM per ton of an air conditioning system typically decreases. As the indoor wet bulb temperature rises, the system may need to increase its airflow rate (CFM) to maintain the desired indoor temperature and humidity levels.Â
CFM per Ton based on Changes in Wet Bulb Temperatures
Fact #3Â As the Wet Bulb Temperature goes up, the CFM/Ton decreases.
CFM per Ton using Sensible Heat Only
There are two ways to look at CFM/Ton, one is based on total load, the other based on sensible heat. The system’s sensible heat ratio (SHR) represents the ratio of sensible cooling (temperature reduction) to total cooling (temperature and humidity reduction). Another is sensible heat capacity (SHC) as shown on this chart, which represents the BTU/hr. capacity of the system at the stated conditions. Let’s look at the effect on sensible capacity when the indoor wet bulb temperature changes.
CFM per Ton based on Indoor Wet Bulb Temperature and Sensible Heat
A lower SHC means that a greater portion of the cooling capacity is dedicated to removing moisture from the air rather than reducing its temperature. We can see by this performance chart, that as the indoor wet bulb temperature increases the sensible capacity decreases.
This means that based on our 2400 cfm and the sensible capacity only, our CFM/Ton increases as the wet bulb temperatures increases. This is the exact opposite of the results we get from CFM versus total capacity. Because the system uses more of its capacity for removing moisture there is less left over to remove sensible heat. This is why it’s important to understand the latent heat load generated within a room or brought in for ventilation air or by infiltration.
Fact #4 As the Wet Bulb Temperature goes up, the CFM/Ton increases based on Sensible Heat Only.
Reading Air Conditioning Performance Charts
Here is a different manufacturers performance data for their 6-ton air conditioner. As we already learned in the previous examples, as the outdoor air temperature increases the system capacity decreases. Notice also as the outdoor temperature increases the high side pressure increases from a low of 275 to 527 psi. Also note that the higher the moisture content or the wet bulb temperature the greater the system pressure. The hotter it gets outside the higher the system pressure. As the high side pressure goes up, the low side pressure follows.
Fact #5 Higher Outdoor Temperatures increase discharge and suction pressures.
400 CFM per Ton Rule of Thumb
The “400 CFM per ton” rule of thumb is a commonly used guideline in the HVAC industry to estimate the airflow requirements for air conditioning systems. It suggests that for every ton of cooling capacity provided by the air conditioner, approximately 400 cubic feet per minute (CFM) of airflow should be delivered to the conditioned space.
This rule of thumb is based on a combination of engineering principles, empirical data, and practical experience in the design and operation of air conditioning systems. While it is widely used as a general guideline for estimating airflow requirements, it is important to note that actual airflow needs may vary depending on factors such as climate conditions, building characteristics, equipment efficiency, and occupant comfort preferences.
The 400 CFM per ton rule of thumb is intended to provide a starting point for HVAC designers and engineers to estimate airflow requirements during system design and sizing. However, it is not a substitute for detailed engineering analysis and calculation. It should be used with caution, taking into account the specific requirements and constraints of each project.
Factors that can effect the CFM per Ton or System Capacity
CFM per Ton Calculation Methods
CFM per ton can be based on total BTUH (British Thermal Units per hour) capacity or sensible heat capacity only. This depends on the specific application and design requirements of the air conditioning system.
Total BTUH Capacity
When CFM per ton is based on total BTUH capacity, it accounts for both sensible heat and latent heat removal. This means that the airflow rate (CFM) is calculated to meet the combined cooling load of the space, including both sensible cooling (temperature reduction) and latent cooling (humidity removal). In this case, the airflow rate is typically higher to accommodate the additional energy required for dehumidification.
Sensible Heat Only
Alternatively, CFM per ton can be based on sensible heat capacity only. This approach is commonly used in applications where humidity control is not a primary concern. In these cases, the airflow rate may be lower since it only needs to meet the sensible cooling requirements of the space.
In practice, the choice between total BTUH capacity and sensible heat capacity for calculating CFM per ton depends on factors such as climate conditions, building occupancy, humidity levels, and comfort requirements. HVAC designers and engineers evaluate these factors to determine the most appropriate airflow rate for achieving optimal comfort and energy efficiency in the conditioned space.
How do you serve several small zones with one Variable Refrigerant Volume (VRV) split system without adding additional indoor fancoils, and still provide individual temperature control? Currently to achieve individual temperature control you might need separate fan coils for each room with the ability to control air flow. This is where the Daikin Zoning kit can help.
Would if the building has a bunch of small spaces too small for the smallest VRV indoor fan coil unit? Then the use of air volume dampers to divide up the capacity into smaller zones works best in these scenarios. With the use of the Daikin Zoning kit, the ability to serve small areas is better achieved. This is because zone dampers divide up the air from a single indoor fancoil to serve each space. Daikin’s Zoning Kit eliminates the need for multiple indoor fan coil units to create individual zones. This should save money.Â
This allows smaller spaces to be served and individually controlled. The smallest available indoor fan coil is currently 7,500 Btu/h. If your space required less than 7,500 Btu/h, then you would have a couple of options.
The smallest Fan Coil for this model of Indoor Unit is 7,500 Btu/h. Too large for these small spaces.
One would be to install an oversized indoor fan coil unit for the space or share the air with a fan coil that serves multiple rooms, leaving the room with a lack of individual control. There is the option to have up to 6 separate zone dampers supplying variable air flow to each zone based on the demand.
Daikin Zoning Kit with Six Zones
Daikin Zone Damper Box Construction
The zone kit is basically a sheet metal plenum with zone dampers attached at one end, while the other is attached to the indoor fan coil. The individual zone dampers respond to the demand from the corresponding controller in each space.Â
Controls and Thermostats
Each individual zone damper has a zone thermostat that controls the air flow to the room. The thermostat allows for on/off function, schedule control, temperature set point, touchscreen interface and sleep function. The zone thermostats use 915 MHZ wireless communication and 2 AAA batteries.
All thermostats can be hardwired or just one. They could all be wireless except one needs to be hardwired.
There is also a Main Thermostat with a wired color touch display that is used to configure the zone damper kit and can be used as a room controller. An add on BACnet gateway module allows the control of individual rooms using BACnet/IP compatible building management system. The main thermostat uses AWG 20 – 4 wire (shielded) communication cable supplied with 12 VDC from the main control box. This main controller can control all the zones, eliminating controllers in each zone, while still allowing each zone to have individual set point capabilities.
Hardwired Thermostats
There must be at least one hard wired controller to the control box mounted on the Daikin Zone Kit. The other controllers will communicate wirelessly to the control box which can be up to 164 feet line of site distance from the wireless controllers. There is the option to also hardwire all zone controllers if preferred or if wireless communication is troublesome. In this case, the total wiring allowable for each terminal is 130 feet.
Electrical Power
The DZK control box will need 120/240 VAC power. The control box has an alarm input that allows for an alarm to be used to shut down the fan coil and close all zone dampers. Each of the zone dampers are powered by 12 VDC from the control box.
An interface board provides communication between the zoning control board and the indoor fan coil via the NAV controller.
Lastly, there is the ability for their intelligent Touch Manager (iTM) using the BACnet Client option to provide individual room control.
You can use the DZK with a VRV Heat Pump or Heat Recovery system. See our video on the differences between a VRF Heat Pump and VRF Heat Recovery system.
Compatible Indoor Units and their BTUH, CFM and Static Pressure Chart
Compatible Indoor Fan Coils and Capacities
The Daikin zoning kit can be attached to a compatible ducted indoor fan coil unit that ranges in capacity from approximately 15,000 Btuh to 54,000 Btuh and contains anywhere from 2 to 6 zones. So, depending on the capacity of your indoor fan coil, Daikin provides up to 6 zones with their zoning kit. With the largest indoor unit of 54,000 Btuh this allows the option between 2 to 6 zones, depending on the size of each zone.
4 Zones with a Daikin Zoning Kit (DZK)
There are 4 different zone damper configurations to choose from, and 7 compatible indoor fan coils. The zone damper kits come in 4, 5 and 6 damper configurations. This allows anywhere from 2 to 6 zones to be configured. This allows more than one damper to feed larger zones by combining dampers or allows one damper to serve multiple air distribution outlets.
Air Balancing
The air entering the fan coil is offset from the center of the zone box. This causes some of the zone dampers to receive less air than others. This is particularly relevant with the smaller DZK030E4 & E5 models. This causes a non-uniform air velocity, and the center dampers receive more air, while the outside dampers receive less. If all zone dampers are not required, then they can be blanked off. There must be a minimum of two zone dampers used.
Excessive amounts of refrigerant piping can be reduced by using a Daikin Zoning Kit
Key Benefits of using the Daikin Zoning Kit
Avoid adding indoor fan coils to achieve individual zone control.
The ability to serve an area that is smaller than the smallest VRV indoor unit.
Increased comfort with individual control.
Increase in the VRV systems ability to meet the demand of smaller spaces.
A reduction in the amount of refrigerant required.
