The Condensing Unit


The Condensing Unit

Let’s think about our condensing unit for a moment. For those of you just dibbling around looking for some information you have come to the right spot. The condensing unit is the unit that is on the outside of your house. The condenser performs three functions. It removes heat from refrigerant, condenses the refrigerant vapor back into a liquid and then sub-cools the liquid refrigerant. How fast a condenser can perform these functions can be used to evaluate the condensers performance and efficiency of the system as a whole.

During the removal of heat from the refrigerant, the refrigerant (now in a vapor stage) reaches a saturation point and starts to condense back to a liquid form. The temperature at which this process happens is determined by the pressure being exerted on the vapor thus creating what is known as a Pressure Temperature Relationship.

Knowing this information can assist technicians in evaluating a system. Technicians will determine such buy observing pressures on the high side along with operating pressures coupled with temperature. A systems correct saturation temperature is determined by measuring the outside ambient air temp (the normal outside temperature) and the including the manufacturers condensing design temp which is based on the type of condenser being used in the system. This tells the tech what the saturation temp of the refrigerant should be for the condenser under certain pre-determined conditions.

The above information can then be used to evaluate actual system operating high-side pressures along with saturation temperatures. An actual system pressure and saturation temperature of plus or minus 10% would be acceptable. Any pressure and saturation temperature higher or lower than the allowable 10% range is an indication to the tech that the condenser is working too hard or below an acceptable range. Technicians should look for conditions that could cause the condenser to perform outside the determined acceptable range.

The condensing unit is much more than just a condenser. They hold within them very valuable parts. Depending on what type of system you have will determine what all is located within your condensing unit. Most to all condensing units contain the follow parts:

Condenser: Cools Hot Vapor Refrigerant and turns it into liquid

Reversing Valve: (Heat Pumps) directs the flow of refrigerant depending on setting, Summer/Winter

Compressor: Reciprocating or Scroll, moves the refrigerant throughout the system

Metering Device: (Heat Pump) serves as evaporator coil during Summer Months

Condenser Fan: Draws air around condenser fins for cooling

Refrigerant Valves: For access to obtain system pressures

Controls: Limit Switch, Contactors, Relays, Boards, Capacitors

Condenser FAQ’s

When my compressor is running should my condenser fan run also? Yes, this is a great indication that something is not right.

My heat pump condenser has some ice on it during the winter months, is this ok? Yes that is normal however; keep an eye on your system. Too much ice buildup could indicate a problem for which means the reversing valve is not operating in the defrost mode.

Is it ok to clean my condensing unit ? Yes and No. Yes if you plane to just remove debris from around it but No if you plan to deep clean. This should be left up to a technician because damage to the fins will cause you bigger problems. Never chip around your condenser to remove debris, any slight nick will cause refrigerant to leak.