Ducts are a vitally important, and all-to-rarely considered, part of your forced air heating system. Though they are naturally unobtrusive and often quiet, ducts require just as much consideration during installation as any other part of your heating system. If the ducts are improperly sized during installation, it can have an enormous negative impact on your heating system’s ability to operate. Let’s examine the consequences of installing ducts that are either too large or too small.
Each forced air heating system is equipped with an air handler, which is designed to move a certain volume of air a set distance. This volume changes depending on the size of the system. The different options for duct sizing are meant to match the different sizes of heating systems and their air handlers, so that the proper amount of air is circulated around the house.
By choosing ducts that are too large, you are providing a lot more area for the air handler to cover. As the system itself is not rated to move air that distance, much less air will actually make it into the various rooms that need to be heated. This leads to a dramatic loss in heat output for the heating system, which is a waste of money for you.
Ducts that are too small for your heating system will result in an increase in static pressure. There are two consequences of this. The first is that your ducts will be much noisier than they should be. This should be easy to detect, as the noise is often so loud as to be extremely distracting. The second issue is that your system will have to work much, much harder to heat your home. The system will have to run longer and longer, to adequately heat your home, which will waste more and more money. Undersized ducts will also shorten your heater’s lifespan, as it won’t be getting enough air circulating through it to work properly.