Did you know that properly insulating your heating and cooling ducts in your unfinished basements, attics, crawl spaces and garage can help improve your homes energy efficiency? It is true that a duct system which is not insulated or poorly insulated may result in a 10% to 30% loss of heating or cooling energy.
If any room in your home has a particularly long duct run, it is possible for the air to come out cold in the winter months because you are actually losing all of the heat before the duct makes it to the register.
There are ways to insulate a heating duct to stop it from wasting energy. In this article we will go over how to properly insulate your home’s heating and cooling air ducts to achieve maximum energy efficiency.
Minor Duct Repairs = Major Impact on Heating or Cooling Bills
Some homes may have leaks in their air ducts that can draw in warm air from the attic in the summer and make the air conditioned air less cool. In the winter months, the same leaks will let the heat escape the ducts in unconditioned areas causing higher heating bills. Many of these leaks can be fixed with minor duct repair techniques such as:
1) Replacing old, cracked and dried cloth tape around the seams in the ducts with new fiberglass tape and a Hy-Tech Vapor Mastic.
2) Basements that have been converted into living areas should have both supply and return vents.
3) Be sure you have a well sealed moisture barrier on the outside of air conditioning ducts to prevent moisture build up.
4) Check your duct runs for obvious holes and leaks. Often the duct sections will become separated leaving large gaps for air to escape.
Many homes lose the majority of their efficiency through leaks and gaps in the ducts. The first step to a well insulated duct system is to go over all of the joints with a brushed on mastic. The mastic forms a flexible seal that will not decompose or dry and crack with time.
Many people that use regular duct tape on their ducts have to repair them every year because the duct tape decomposes and dries and cracks terribly. So, despite its name, duct tape should not be used on duct joints if you want a seal that will last.
After all of your ducts joints are well sealed and you have checked the entire run for leaks and repaired them, you should wrap a thin insulated blanket around the duct work.
Duct Insulation Choices
There are several alternatives for insulating your home’s ducts, they include:
• Rigid fiberglass insulation: The insulation is cut into sections of a length that wraps around the duct and the sections are often held together with a foil tape. It is usually a better practice to staple the sections with a staple gun rather then to use foil tape.
• Faced fiberglass: Faced fiberglass has fiberglass on one side and foil on the other. The fiberglass side goes against the duct work while the shiny foil side faces out. The foil protects the outside of the insulation and protects the fiberglass within as well. The foil helps to prevent conductive heat loss.
• Reflectix: Reflectix is reflective insulating wrap that is designed to achieve less heat loss. It is made up of foil faces that contain bubble pack between layers of polyethylene to make it stronger. Reflectix is said to reflect 97% of radiant heat, keeping ducts warmer in winter and cooler in the summer. Reflectix has 7 layers and is only 5/16 of an inch thick. It takes two inches of fiberglass insulation to achieve the same performance as a single application of the 5/16 inch Reflectix.
Fixing holes and leaky joints in your duct work is best achieved by brushing on a mastic and not using duct tape. Once your certain all of your leaks are fixed, you have several choices for what type of insulation to use. You should check local building codes to see if there is an R-Value rating on insulation recommended for your area.
R-value ratings typically range from R-2 to R-11, but in almost all cases you are safe with an insulation with an R rating of R4 or better. You will find that most of the insulation options will achieve this easily. Your decision may depend on the bulk of the insulation, in which case the Reflectix is less bulky, or if you want something less costly, you may decide to go with a rigid fiberglass insulation.
Photo by Belinda Hankins Miller- Creative Commons Attribution License