The Ductwork: Stop Energy-draining Leaks

Ductwork can be a major cause of heat loss. In fact, PG&E research shows that faulty ductwork accounts for more than 25 percent of the heating loss in an average California home. That means dollars out of your pocket. The good news is that ductwork problems are relatively easy and inexpensive to correct. Skip these links to continue with rest of content.

Repair Disconnected Ducts

Disconnected ducts are common and a big source of heat loss—yet they are simple to reattach with duct ties and mastic. If an attic or crawl space duct comes loose and goes unrepaired, you can loose a tremendous amount of heat and money. In essence, you could be paying hundreds of dollars a year to heat the outdoors. The disconnected ducts also unbalance the recirculation of the heating system, which can create unsafe operating conditions. If you have a room that never gets warm, check behind vents or in crawl spaces for disconnected or crushed ducts.

Seal Leaks

Either you or a professional heating contractor should check the entire length of your ductwork for leaks, even very small ones. Turn the furnace on and feel along the duct for escaping warm air. Also look for tell-tale black marks on the duct's insulation—these are usually the signs of leaks. Have your heating contractor seal any leaks carefully with mastic-type sealant—not duct tape. Duct tape is not a long term fix. Don't forget to seal leaks where your furnace connects with your ductwork.

It's now possible for a contractor to perform verified duct sealing by using a special fan to test duct system leakage before and after sealing efforts have been made. Research shows that verified duct sealing allows the contractor to be sure that the real leaks in the ducts are repaired.

Insulate Ducts in Unheated Spaces

Most heating ducts are in crawl spaces, attics and outdoor locations. If your ducts aren't already insulated, do it now using R-6 or higher fiberglass duct wrap. Check to ensure that hanging flexible ducts are supported every four feet with an inch and a half wide, or wider hanging strap.


Adding insulation to your attic area, walls and floors will substantially improve the efficiency and comfort of your home.