3 Things to Know About Checking Refrigerant Pressure After HVAC School

May 31, 2022

If you’re pursuing an HVAC career, one of your main responsibilities will be to service and repair air conditioning units. Along with other routine maintenance tasks, you’ll need to perform refrigerant pressure checks. Refrigerants are chemical compounds which absorb heat from the surrounding environment. During a refrigerant cycle, refrigerants will repeatedly change from a fluid to a gaseous state depending on their temperature, moving through the cycle’s components in order to reroute heat to other areas. Refrigerants are used mainly in air-conditioning systems, heat pumps, refrigerators, and freezers.

At NATS, you’ll receive hands-on training to pursue an HVAC technician apprenticeship, learning how to install and maintain gas and propane heating systems, air conditioning units, and ventilation equipment for both commercial and residential environments. Below, get a head start on your training by discovering a few key things to note about checking refrigerant pressure. 

Checking Refrigerant Pressure Requires an Understanding of the Refrigerant Cycle

As an HVAC technician, understanding the ins and outs of refrigerant pressure won’t be possible without basic knowledge of refrigerant cycles. Refrigerant cycles consist of four basic components: the compressor, condenser, expansion device, and evaporator. The compressor is what uses the most power in an HVAC system–responsible for compressing gaseous refrigerant in a cooler state to a high-pressure, high temperature vapour. From here, the refrigerant is cooled by the compressor, a coil filled with hot refrigerant which wraps around the system to diffuse heat. Next, the expansion device works to reduce the refrigerant pressure quickly to prepare it for evaporation. Evaporation will occur in the evaporator, which boils the refrigerant. Through these exchanges in energy and changes in matter, refrigerant regulates the temperature of a system.

As an HVAC technician, it’s important to understand how refrigerant cycles operate

What Condensing Pressure of a Refrigerant Means for an HVAC Technician

When refrigerant changes from a gas to a liquid within a cycle, this creates what’s known as condensing pressure; a form of condensation. This occurs when refrigerant moves through the condenser, releasing heat as its temperature drops to the temperature of condensation. The condenser is a cooling system composed of tubes which expand over a large surface area to remove the greatest possible amount of heat. The condensing pressure, which results from the release of heat and sudden drop in temperature, can be read by a pressure gauge. While this gauge can be placed anywhere between the metering device and compressor, it should be placed as close as possible to the condenser in order to obtain an accurate value. During your HVAC technician career, it’s important to remember that a higher-than-normal pressure could indicate problems with the condenser coil, broken or faulty fans, or even leaking refrigerant.

A pressure gauge is used to determine the condensing pressure

Evaporating Pressure is the Opposite of Condensing Pressure

When you enrol in HVAC technician courses, you’ll also become familiar with refrigerant’s evaporating pressure. A refrigerant’s evaporating pressure is the opposite of condensing pressure. During this phase, the refrigerant chemical compound is vapourized, changing from a liquid to a gaseous state and absorbing heat from its surroundings. When the refrigerant moves through the suction line and evaporator, the valve and line pressure drop. As with condensing pressure, the evaporating pressure can be read using a pressure gauge that’s situated and connected anywhere between the compressor and metering device. A refrigerant’s chemical compound enters the evaporator as a low pressure, cold liquid, but as it absorbs heat, it begins to boil and evaporate. 

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