The Effects of Adding a Duct on an Air Conditioning Unit

Ductwork is best done when the structure is in the framing stage.air conditioner, conditioning image by Greg Pickens from Fotolia.com

Your central air conditioner is not doing the job. The weather is not cooperating, and your home is either too hot or too cold. What's the solution? For many homeowners, adding a duct on the air conditioner unit is the way to go. While it would have been easier to add a duct while the home was being built, it's not impossible to do some modifications. But what are the ramifications of doing so, and are they worth it?

Effect on Airflow Distribution

Adding a duct will affect the airflow to all other ducts. Why? Because contrary to popular belief, adding a duct doesn't increase the amount of air flowing into your home. The size of your unit is the determining factor in how much air your home receives. The duct work just decides where the air is distributed. You could very well be robbing Peter to pay Paul if you add a duct in one room without thought to the other rooms. Consider modulating where the air flows by adjusting the vents in each room. Are there rooms in your house that you don't go in often? Why not shut the vents in those rooms to divert air into more populated spaces.

Consider the effect on your home's space. If you have to add a duct by cutting into a wall, the prime place to run the ductwork is through a closet wall. Closet walls are considered non-living space and offer clever options to modify the wiring or pipework in a home. Although these changes are largely out of sight, often the homeowner must move storage items or clothing into another closet or room, cramming that particular living space. While it may seem like a small price to pay, you could end up cluttering a room, all because you wanted a hidden duct to run in a closet.

Adding a duct can also decrease your unit's efficiency. There's a reason why the HVAC installer put only a certain number of ducts in the house in the first place. The installer performs precise calculations involving the home's square footage to determine the size of the unit. Adding a duct, especially in the wrong place, can wildly throw off the unit's energy output. In effect, it could cause your unit to run longer to cool the house, increasing the energy bill. In summary, before you consider adding an air conditioner duct, consult an HVAC expert.