This article will help to explain what the different parts of a home Heating, Ventilating and Air Conditioning (HVAC) system are and help you understand what work is being specified on an hvac maintenance price list. For the purposes of this example, we will look at the components of an all-electric split heat pump system most typical in home HVAC installations.
The heat pump itself is the outdoor portion of the system. It consists primarily of the compressor, condenser coil, and fan. It also houses the reversing valve and electrical contractors. This is where your service technician will hook up his pressure gauges to see if there is the correct amount of refrigerant in your system. If refrigerant is needed, it is installed here through a port. The bottle containing the freon will be weighed by a scale before and after filling your system to determine how much was used, and you would be charged by the pound. If there is a refrigerant leak in the coil it can usually be repaired, but all the refrigerant may have to be pumped out and reinstalled.
Sometimes the fins on the condenser coil will be bent up due to hail damage or may be dirty. These can be combed out again or cleaned for little cost. If the fan or compressor do not run, or the reversing valve does not change the system from heating to cooling, it is possible that only a contactor may need to be replaced. These contactors, thankfully, are low cost components. But if a fan motor or compressor needs to be replaced, it can be more expensive. The compressor is the most expensive component and can be several hundred dollars to replace. If the condenser coil is badly damaged or the compressor needs to be replaced, it might be time to consider a new heat pump, particularly if much more energy-efficient options are available.
Indoors you have the air handler, which consists of the evaporator coils, indoor fan, air filtration system, humidifier, and a plenum for air vents. One of the most expensive repairs here can be for an under-slab plenum that has rusted out; this can sometimes require that part of the slab be demolished and reconstructed. It is unusual that anything goes wrong with the evaporator coils, but sometimes they need to be cleaned, which is an inexpensive operation. If the indoor fan motor needs to be replaced, it can be moderately costly. The air filtration system and humidifier usually only require simple repairs, replacement of filters, floats, small motors, etc. There are also some control electronics including the thermostat; these can range in price from inexpensive to moderately costly. If the heat pump outside needs to be replaced, it is possible that you may want to replace the indoor air handler also if it will help provide you with the energy efficiency of a new system.
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