If you're building a new home and have reached the point where you have to choose an HVAC system arrangement, one option you may be coming across is the use of floor ducts. In this type of arrangement, the ducts for your HVAC system are run under the floor rather than through an attic. Whether or not you would benefit from this arrangement will depend on your preferences. Here's a look at the pros and cons of under-floor HVAC ducts.
Pro: Heat will be distributed more evenly.
Hot air rises. So when ducts are run through the attics and ceilings, the top halves of rooms tend to get super warm, while the bottom halves of rooms tend to stay chillier. Running ducts under the floors (and placing vents along the floor as is common with this arrangement) will ensure that the heat stays distributed more evenly. Your floors will also feel warmer, which will make the whole space feel more comfortable since you won't feel the chill of a cold floor each time you walk across it.
Cons: Air conditioning will be a bit less efficient.
The "hot air rises" rule also holds true in the summer. As a result, with ducts running under the floor, your home won't cool as evenly. Your AC bills might be slightly higher as a result. This is a trade-off you might be willing to make if you live in an area where you rarely have to turn on the AC. However, if you predominantly use the AC and rarely heat your home, having ducts under the floors might not be the best option.
Pros: You won't have as much heat loss through the ducts.
When ducts are run through the ceiling or attic, there's not a lot of "home" surrounding them. So a good amount of heat loss occurs. In the summer, warm air on the outside of the ducts warms them up, deceasing your AC efficiency. In the winter, heat is lost through duct walls before it makes it into your rooms. When the ducts are placed under the floor, they're surrounded by more "home," so essentially they are better insulated and experience less heat loss.
Cons: Kids may clog the ducts with toys and other items.
Since systems with ducts beneath the floors have vents that are located on the floor or the lower portion of the wall, kids can reach these vents easily. They could drop toys and other items into the ducts, which would slow air flow through the system. This is not typically an issue when ducts are run through the ceiling since the vents are then placed far up on the wall.
For more information and advice on your options, contact an HVAC contractor at a company like Dick Kearsley Service Center.