Furnace and Air Handler Configurations
You likely have in your home one of two basic air delivery systems, either of which will be necessary to operate a central air conditioner: a furnace or an air handler. A furnace is comprised of a heating device (gas or electric), as well as an air circulating fan. An air handler looks very much like a furnace, but has a circulating fan without heating capability. Additionally, an air handler has an evaporator coil built-in for air conditioning (or heat pump) usage.
Your furnace or air handler will be configured one of three ways: up-flow, down-flow, or horizontal-flow. Looking at your unit will likely inform you of which one you have. If your furnace/ air handler is vertically aligned, then it is up-flow or down-flow. If it is horizontally aligned, it is horizontal-flow (please see pictures below).
Depending on which furnace configuration you have will help determine which one of the three types of corresponding evaporator coils (cased coil, uncased coil or horizontal coil) you will need for your home’s particular air conditioning system. If your home will use an air handler instead of a furnace, you will not need to purchase an evaporator coil separately since it is already built into the air handler.