Mendocino County: 707.485.5158     |     Sonoma County: 707.579.5158     |     Lake County: 877.485.5158

Duct Testing and Sealing

When your furnace or central air conditioner changes the temperature of the air and returns that air back out to each individual room of your home or business, the air travels thru a series of pipes. The journey begins at a big square box called a plenum and then enters a large duct called a trunk. This duct is usually the largest and can be 12-16” in diameter and carries a high volume of heated or cooled air to the farthest points of the structure. As it nears its objective, the ducts tend to get smaller so that when they finally reach their end, they may only be 6” in diameter. Most often, the ducts travel in unconditioned space, located in either the crawl space or the attic of the home. They therefore must be insulated and should be sealed against leakage, as any leaks will be allowing conditioned air to spill out into the attic or under floor areas and be wasted. 

Address Your Duct Leaks

It’s been common practice over the years to just allow the ducts to leak and not to spend a lot of time in making sure the connections made at the metal fittings or at the “boots” (the metal boxes designed to have the visible register installed on it) be made with much regard to being leak proof. It has always been cheaper in the past to just let the joints leak and install a bigger furnace. 

Historically energy has always been so inexpensive that we could get away with this, and there was never any reason to change. So we have had brand new duct systems that leak from 25%-40%. That’s one quarter to almost one half of the conditioned air from a brand new energy efficient furnace or high efficiency A/C just running out under the house or into the attic. And as we all know, utilities cost more now.  It doesn’t make sense to just throw in the next bigger size unit and walk away.

Solving Your Leaky Duct Problem

Fortunately, most of the leakage points can be reached from inside the house. By removing the registers and then cleaning out the debris in the ducts, we can seal the joints at the flex duct to the 90-degree bend and the 90-degree to the boot, then from the boot to the floor or drywall. We do this at every register and at the return air grill. We can also reach the supply plenum and can seal the dovetail cuts where the holes were cut to allow the round ducts to attach to the plenum. Sealing these joints was never a consistent thing and a lot of leakage occurs here. By just addressing these two areas, we can typically cut duct leakage from around 42% to as low as 15%. This makes a tremendous difference in the performance of the HVAC system, and the cost is very reasonable. 

Duct Sealing Rebates

PG&E and the Cities feel this is such a worthwhile thing that they all offer some sort of cash rebate for duct sealing. Sometimes you have to do a package of things as well but they are usually things that make the most sense. PG&E has what they call their “Basic” program. We can not only do the duct sealing on your system, we can also provide air sealing for the whole house, install attic insulation. Once you have done all this great stuff, you get a rebate. And if you have a small house, it may not cost much more than the rebate to do the whole thing!

If you just want your ducts sealed we are glad to do that, however we’ll need to give you a price first because each house is different, but you can figure a standard home with 6-10 registers in the floor, not over 2,000 sq ft is going to be about $300-$500 to seal all the supply and return ducts. If you take your leakage from 42% to 15%, you will recoup that money invested in just one or two heating seasons.  And if you are located in the City of Ukiah or Healdsburg, there may be additional rebates available as well. 

For more information about blower door testing, or to schedule a free phone consultation today, contact us here!