"I'll be seeing you...in all the unconditioned spaces," goes the old song. OK, not quite, but you really should
add duct insulation there. A home with central heating can lose
up to 60 percent of its heated air before it even reaches the vents
if ductwork isn't well-connected and insulated, or if it goes through unheated spaces, according to the Department of Energy. That results in wasted money and an uncomfortable house. On the flip side,
adding duct insulation in unconditioned places can save money and make rooms less stuffy.
The unconditioned spaces in your home include the
attic,
basement, and
crawlspaces. Ducts aren't always easy to see, but you can often find them exposed in those areas.
Extra duct insulation in conditioned spaces (such as living areas) can be beneficial too, even though they experience less heating and air conditioning fluctuation. Since you can save energy on home heating and cooling, you can also help reduce pollution.
1. Look for obvious places in the attic, basement, or in crawlspaces where ducts have become disconnected and reconnect them.
2. Fix remaining gaps with metal-backed tape or aerosol sealant.
3. Following the manufacturer's instructions, use duct mastic to seal joints.
4. Wrap the outsides of ducts with insulation and then seal the insulation with tape.
Don't use duct tape. Ironically, you shouldn't use duct tape to fix gaps, because it doesn't last over time. Repair places where pipes are pinched (which impedes flow of heated air to the house) and fix gaps with a metal-backed tape instead.
Insulate to at least R-6. The R-value of insulation indicates the insulation's level of resistance to heat flow. Typically, duct insulation has an R-value of R-4. The ideal R-value for insulating your ducts varies based on your climate. A higher R-value is recommended for colder climates to boost home heating.
Watch out for wires and lighting fixtures. Although the cost will be substantially more, it's a good idea to get a professional to help add duct insulation when electrical wires or lighting fixtures are nearby.
Vacuum ducts every few years. Ducts should be vacuumed once every few years, to clean out the dust, animal hair, and other gunk that can gather in them and cause respiratory problems.