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Residential AC systems are usually replaced piece by piece over time, not all at once. But there are some instances when you choose a new AC system for your home, particularly when you build a home, or buy one that was built before the advent of modern air conditioning.  In either case, your choice of air conditioning systems design can have a significant impact on (a) how well your home cools and (b) the cost of cooling it. Below, we discuss the advantages and disadvantages of four types of air conditioning systems design that people commonly place in their homes.

1. Window Units

Window units are implemented for two reasons: they cost less than central AC equipment, and they help to preserve classic interiors. Concerning cost, the money you save on window units will be nothing compared to the cost of running them if you run them full time. Concerning classic interiors, many HVAC services offer ductless or mini duct air conditioning, which don’t disturb ceilings and walls during installation, and provide a better interior and exterior aesthetics than unsightly window units.

2. Ductless Mini-Split System

Ductless mini split systems are a good replacement for window units in older homes, combining an outside compressor with an indoor air handler discreetly positioned in each cooling zone. Instead of being distributed through ducts, airflow is distributed by the handlers, with each connected to the compressor through a conduit containing lines of electricity, condensate, and refrigerant. In addition to preserving classic interiors, ductless mini-split arrangements also avoid the cost of duct maintenance. However, they could multiply the average cost of handler equipment and maintenance.

3. Small Diameter High Velocity System

Small diameter high velocity systems use ductwork that features a smaller diameter, greater flexibility, and produces higher velocity airflow than conventional duct arrangements. These characteristics make small diameter high velocity ducts ideal for homes that (a) have fine interiors that should be preserved, and (b) aren’t designed to hold in coolness with the same efficiency as modern homes. The systems’ downside is they use more energy than conventional duct arrangements, though this is often due to the inefficiency of the homes they cool.

4. Conventional Duct System

If you’re building a new home, a conventional duct system may be the best choice for three reasons: it involves less utility cost, less equipment cost, and lower maintenance/replacement cost than window units, mini-split ducts, and small diameter high velocity ducts, savings that add up to thousands of dollars over time. The downside of conventional duct arrangements is duct maintenance, which involves cleaning and resealing leaky seals. In general, however, duct maintenance is quick and inexpensive.