#hvacquality Archives - United CoolAir

May 4, 2022 by Matt Hanson

BTUs in Air Conditioning

When it comes to air conditioning, calculating BTUs is an essential part of determining the size of the unit. A BTU or British Thermal Unit is the measure of heat energy that comes from a thermal unit and an Imperial Gallon is 10 pounds in weight. Therefore, a BTU is 1/10 of an Imperial Gallon or one pound of water at sea level and a BTU will raise water temperature one degree Fahrenheit. However, in air-conditioning, we are not changing water temperature, but the temperature of the air. While the metric system has taken over most industries, BTUs in air conditioning remains the standard due to their significance in heating and cooling.

What does a BTU do?

Simply put, a BTU measurement shows how much energy an AC unit uses to remove heat from a space within an hour. This allows HVAC techs to determine what size HVAC units should be installed. When an HVAC tech determines BTU usage, they must account for many factors. Every BTU has a corresponding tonnage, which has nothing to do with weight but is in reference to a unit’s cooling capacity.

A ton of cooling known as refrigeration is the amount of heat it takes to melt a pound of ice in a 24-hour period. Furthermore, 12,000 BTUs is equal to one ton of cooling and there are guidelines for how many BTUs are needed for the square footage of a space. Also, heat in air conditioning is referring to energy and not temperature. Air conditioning systems simply move energy from one place to another.

Square Fee	BTUs
100-150	5,000
150-250	6,000
250-300	7,000
300-350	8,000
350-400	9,000
400-450	10,000
450-500	12,000
500-700	14,000
700-1,000	18,000
1,000-1,200	21,000
1,200-1,400	23,000
1,400-1,500	24,000
1,500-2,000	30,000
2,000-2,500	34,000

Here is a resource to quickly calculate the BTUs needed.

Calculator

Conclusion

Many factors go into choosing an HVAC system and BTUs are just one factor in this calculation. It also helps in determining kilowatts which has a direct impact on energy costs. Equally important are room size, aspects of insulation, humidity levels, ceiling height, window size, and room occupancy. Being informed of all these factors make sure the perfect sized HVAC unit is installed to serve the cooling needs.

October 14, 2020 by Matt Hanson

Compressor Failure and the Effects on Warranty

Identifying why compressor failure is subject to many variables and is important to understanding warranty implications. Although compressors fail for a multitude of reasons, poor installation and maintenance are the most common causes. However, for the vast majority of compressors returned for claims, rarely is it due to a defect in the manufacturer supplied part.

Determining why a compressor has failed is a challenge for contractors of light commercial cooling systems. The mere fact that installation and maintenance procedures are key factors means that most compressor failures are preventable. Therefore, it is of the utmost importance to understand the various ways in which these failures occur.

Following OEM guidelines for installation, startup and service are critical for installers of both ducted and ductless systems. For instance, the act of completing a compressor changeout can introduce contaminants to an HVAC system. Conversely, there is the rare occurrence of natural causes such as lightning or line voltage fluctuations that happen. On the other hand, proper routine maintenance improves the long-term reliability of the system.

This allows technicians to identify issues before they can cause a catastrophic failure. For instance, a dirty outdoor unit coil will result in the inability to reject heat, thus increasing compressor operating temperatures. When this happens, the compressor forces more expended energy while providing less capacity. Therefore, regular routine maintenance is key to keeping a system running well and avoiding compressor breakdown.

Other factors that affect compressor life

When it comes to compressor endurance, keeping refrigerant lines free of moisture or oxidization is very important. When refrigerant lines become contaminated it causes the internal lubricant to become acidic, which can eat away at internal windings.

Another factor contributing to compressor failure is incorrect refrigerant line sizing. When this occurs, it affects pressurization and evacuation to ensure the absence of leaks. It is also important to have correct minimum unit clearance and refrigerant charging procedures. These factors are critical to longevity and the life expectancy of the compressor.

Overheating is yet another variable that causes compressors to lose their operating capabilities. This usually happens when there is not enough refrigerant in the system. When overheating happens over an extended period it will cause the breakdown of winding insulation. Symptoms of overheating may include compressor short cycling due to increased trips on protection devices. This reduces heating and/or cooling performance, and an increases current draw.

Training and Startup Procedures

Contractors can help mitigate the chances of compressor failure by adhering to each manufacture’s startup procedure. This is because each manufacture has unique steps that must transpire in order to keep equipment running smoothly. Finally, attending a manufacturer training session is a good step in achieving longevity in HVAC systems.

January 6, 2020 by Kevin Stepp

Recovering Energy from Class 2 Exhaust Air

The Problem

Providing a healthy environment must be the top priority for any air conditioning design. This can be difficult though, especially in spaces that generate less-than-ideal breathing conditions. Nail salons, health clubs, and bathrooms are just a few examples of spaces where processes or people taint the air with undesirable chemicals or odors. In these spaces, building designers are missing an opportunity to save valuable energy while providing healthy buildings.

ASHRAE 62.1 – 2019 designates air in these spaces as Class 2 air and stipulates that it must be exhausted. Fresh, but expensive to treat, outside air must be brought into the building to replace the exhaust. Here, designers are dropping the ball if they simply throw away the exhaust air. It contains valuable heat energy that should be recovered and used to reduce the energy needed to condition outside air.

The Solution

United CoolAir’s Alpha Aire utilizes two energy recovery devices to extract heat energy from the exhaust and pre-cool (in summer) and pre-heat (in winter) outside air before it reaches a coil. The unit design reduces the load on the cooling and heating coils to as little as 1/3rd that of a standard outside air unit. At a fraction of the operating cost, Alpha Aire delivers room-neutral (roughly 73° and 50% RH), fresh air to a building.

One common concern with Class 2 applications is whether the exhaust air will be transferred back into the building by way of the energy recovery wheel. United CoolAir utilizes a molecular sieve enthalpy wheel with a rated EATR of 0.5% or less. This means that less than one half of one percent of air leaving the building will be trapped in the wheel and recirculated into the space, a rate undetectable to humans and one far lower than the 10% allowed by ASHRAE 62.1 – 2019.
Designers should not hesitate to use all of the energy at their disposal. Alpha Aire gives them the opportunity to do just that. Call or click the link above to find out more.

Applications

Toilet rooms	Nail salons	Museums
Locker rooms	Pet shops	Hotels
Shower rooms	Barber shops	Health clubs
Science labs	Restaurants	Laundry rooms
Libraries	Bars	Pharmacies
Art classrooms	Bowling alleys	Churches

September 13, 2019 by Matt Hanson

All about packaged units in air conditioning

Since the invention of the air conditioner in 1902, engineers have developed various ways of handling the HVAC process. The evaporator and condenser sections are the two major components of Heating, Ventilation and Air Conditioning (HVAC). This is the case as it applies to Direct Expansion (DX) type systems. At the same time, the indoor air absorbs heat inside the evaporator section. The condenser converts the vapor to a liquid by cooling it down. This section is usually located outside on the roof or on the ground. Because the two sections are located in different areas we call this a split system.

A packaged unit is when the heating and cooling components are contained in the same unit. This type of system can be beneficial when space is minimal. Many times, the placement of this type of HVAC is located outdoors but can also be installed completely indoors. Connected to both the supply and return air ducts; these operate similar to a central air system. The delivery of these packaged units can occur as both air-cooled or water-cooled systems.

The Refrigeration Cycle

In the refrigerant cycle, air-cooled or water-cooled liquid travels through an expansion valve where it converts to a vapor. The vapor then absorbs heat inside the evaporator before moving on to the compressor. After the compressor, the vapor then goes to the condenser where the refrigerant is air or water-cooled. The application of a heat exchanger component is installed with shell and tube; plate and frame, or coil.

The cooling effect is achievable by means of a continuous supply of water added to the system. Sometimes building codes do not permit an HVAC system to be installed outside. In this case, packaged units are installed as a solution. United CoolAir produces these all-indoor packaged systems. By the way, the self-contained HVAC units and are available with multiple air path configurations.

August 30, 2019 by Matt Hanson

What is a Heat Pump and how does it work?

A heat pump represents a growing segment of the HVAC industry. In practical terms, it is a reversal of how the air conditioning system works. While air conditioners are used to cool air; a heat pump can be used to cool or heat the air. This is especially true conditions are in place for this use. Therefore, it is necessary to employ a heat pump where temperatures are more moderate. The Summer months of the mid-south area of the United States contains the ideal conditions for this type of system. Conversely, they can be converted into a heating application when the temps are a bit cooler. In areas such as Florida or California where temperatures are mostly warm, it is best to use an air conditioner only.

The Heat Pump Refrigeration Cycle

Heat pumps use a reverse refrigeration cycle as opposed to the regular vapor compression cycle of an ac unit. Heat pumps use the condenser section to generate heat whereas an air conditioner uses it to reject heat. A heat pump uses a small amount of energy to move heat from one location to another. In a similar way it can cool a building or office space by working in reverse.

Air conditioners and heat pumps work in a very similar way. The biggest advantage to a heat pump is to negate the unit handling the separate loads of heating and cooling. Since the heat pump is only transferring heat it can operate by electricity. Additionally, the unit does not rely on the burning of fuel to accomplish the process.

In the cooler months, a reversing valve reroutes the refrigerant path making the outdoor condensing coil function as the evaporator. In a likewise manner the indoor coil serves as the condenser. The evaporator absorbs the outdoor heat and is in turn used by the condenser to heat the indoor space. However, there is one remaining problem. The outdoor evaporator absorbs heat and must operate at temperatures lower than the outside air. This low operating temperature causes ice to build-up on the outside of the evaporator. Finally, auxiliary heat is used during the defrost cycle to provide indoor heat during this stage.