In the minds of many people, the air conditioner in their home consists of a thermostat on the wall, and a machine outside- by dialing down the temperature setting on the thermostat, the house cools down, as if by magic. The reality is very different than that. First, the HVAC system is the largest, most complex, and most expensive (lifetime cost) than any other appliance in the home. It consists of: Air Handler (does all the hard work of heat transfer and air movement), Ductwork (distributes the air to the different areas of the home), and Condenser (outside unit, basically a refrigerant pump). Let’s take a look at all 3.
Air handler:
Consists of a blower motor, evaporator coil and drain pan, and electric heater. The Air handler is basically the system’s “lungs”. It draws in the warm air from inside the home, and moves it across the cold evaporator coil. The warm air is cooled by the cold coil, and also drops it’s moisture as it passes over the cold aluminum fins. This process is repeated over and over until the temperature inside the home matches what the thermostat is set at. The more this runs, the colder the inside air gets, and the more water is removed. This water runs off the evaporator coil and into the unit’s drain pan, where it then runs out of the home via the drain line. The Air handler is 100% dependent on the duct system to deliver the air with as little resistance as possible, and dependent on the condenser to pump the correct amount of refrigerant, at the correct temperatures. Failure of either the duct system or the condenser make the Air Handler Ineffective.
Ductwork:
The ductwork is a series of insulated “pipes” of varying sizes that deliver the air to the supply and return vents of the home. Return vents bring the warm air to the machine, supply vents bring the conditioned air to the home. Improperly sized ductwork is one of the biggest problems in our area. Ductwork that is too small cause a much higher resistance to the blower motor, causing the air to move too fast through the system; this causes poor humidity removal, as well as providing stress on the blower motor, as well as causing major problems with the compressor, drain system, and mold issues. Resistance pressure is measured by “static pressure”- all systems have a maximum static pressure rating that should never be exceeded.
Condenser:
| Outside, this machine is the refrigerant pump. It consists of a compressor, a fan motor, and a coil. The compressor condenses the refrigerant to a liquid form, and pumps it to the Air handler, where it passes through a “metering device” that basically sprays the liquid refrigerant into the evaporator coil, where the liquid refrigerant “evaporates” into a vapor. This change of state turns the refrigerant ice cold- the warm air being brought into the home now passes over this coil, warming the ice cold refrigerant. This refrigerant in vapor form picks up the heat from the inside air, and travels back to the compressor, where the vapor form refrigerant is compressed back into a liquid form. Once compressed, it travels through the outside coil where it is cooled by the air movement through the coil by the outdoor fan. In essence, the heat coming from the top of your condenser is the heat being removed from your home. This process is repeated over and over until the thermostat is satisfied. |
Notes:
It is extremely important that all areas of the HVAC system are kept clean and clear of obstruction. Dirty filters and coils cause the machine to work harder, run longer, and produce less. This is a bad cycle that cannot be stopped until the dirt or obstructions are cleared.
Drains:
Clogged drains are the #1 service call in our area. A normal residential AC can produce up to 20 gallons of water per day. AC drains and drain lines are the perfect breeding ground for algae, which builds up until a clog is formed. In some cases, years of improper service can lead to drains not being able to remove the water being made, and require replacing. There is limited service that can be applied to a drain- algaecide should be used every 6 months, and routine vacuuming is required. Drain issues happen to 100% of AC systems in our area- it’s a matter of “when”, not “if”.