Air Conditioner: Bigger Isn't Always Better When Reusing Furnace Air Handler Systems

When deciding to switch from a window air conditioner to a central air conditioning system, you can either decide to build out the air conditioner's air handling system from scratch or, if you are lucky enough to have an already-installed furnace in place, you can decide to use its air handling system.

Using the existing air handling system is cheaper and less time consuming. It might also save your house from having to be ripped apart in a bid to create space for installation of new supply ducts and an entire blower assembly.

However, if you are not careful, using an existing system can end up being an air conditioning nightmare. This is especially so if you choose an evaporator coil that is too large for the existing air handling system.

Cooling inefficiency

While installing a unit with a larger evaporator coil may seem like a good idea, it usually turns into a liability mainly because the blower fans and the duct system in place might not be able to meet the demands of your unit.

Using a unit with a larger coil can lead to cooling inefficiencies. This is because it can lead to icing at the coils, something that will reduce the efficiency of heat transfer at the coil area.

Icing explained

The refrigerant usually changes states at the evaporator – from liquid to gas. This is a process that is accompanied by the absorption of heat and hence usually has a cooling effect on the air passing over the coil. Freezing doesn't usually happen in this area because of an adequate supply of warm air that the blower fans push through the duct system.

However, the larger the coil a unit has, the more the evaporation that happens at the coil area and the more the air that is needed to keep the area ice-free. Therefore, if the system that you are taking advantage of isn't powerful enough to supply the evaporator with enough air, freezing will occur. Ice will coat the unit's coil – something that will eventually reduce the efficiency of your air conditioning system.

Energy bill increase

With time, you air conditioner will have to work harder in order to keep your home comfortable. It will therefore end up using more energy than is necessary. This will translate into an unnecessary increase in the energy bills that you will have to cover.

Adjusting the speed of the air handler fan will increase the air flow within the supply ducts. It may therefore help to reduce the risks of ice formation at the coil area. If this doesn't work, then you should consider either replacing the unit or constructing an air handling unit that is powerful enough to satisfy its needs. For more information, contact a place like Elite Heating & Air Conditioning HVAC.