We received quite a few inquiries after discussing duct cleaning and what causes ductwork to appear dirty. Most people wanted more information on duct testing, sealing and repairing, or when it is time to consider a replacement. So let’s take a deeper dive, shall we?
The most important thing to take away from this article is that any of the below suggestions, when done stand alone and not at the time of equipment replacement, will then not need to be done at the time of equipment replacement. This means you can save money now (lower energy costs) and save money later (these repairs won’t have to be done as required by state and local regulations). Consumers biggest concern is typically redundant spending on something. This will not be the case with duct testing and repairs/replacement.
The Department of Energy studies have shown up to 40% of the air can be lost due to leaks in the duct system. In the past, that meant over sizing heating and air equipment to compensate. Which means spending more money upfront on the system and more money on utility bills. Here in California that isn’t the case. Title-24 requires us to test the ductwork on each heating and air system replacement. We have to meet or beat a maximum duct leakage of 15% on existing duct systems or 5% on new duct systems. This is why if you do it now, you are saving us time and materials at the point of equipment replacement which in turn will save you money.
How it is done: If you call to have us test your duct system we come out with our DuctBlaster machine. We seal all of the supply registers to the ceiling with plastic and attach the DuctBlaster to the return air duct to pressurize the duct system. In doing this it can measure air leakage by pressure drop using a manometer. Once we know how much air is being lost, we can do a visual inspection of the ductwork to see where the air is leaking from.
If the leakage is minor, it is typically something the homeowner can do themselves as explained in our duct cleaning article.
Supply box after- sealed with foil backed duct tapeSealing all of the ceiling or floor supply metal boxes to the sheetrock (or subfloor) with heavy-duty foil- backed duct tape will prevent attic (or crawlspace) air from being pulled into the home. This is a huge benefit for indoor air quality if nothing else. The return air boxes can be sealed in this manner as well.
The next sneakiest culprit is usually at any metal joints where ducts connect. These joints are typically wrapped in yellow insulation. If the insulation is still yellow, all is good. If the insulation is brown, unwrap and seal with mastic by paintbrush on any metal joint and rewrap in insulation. Our clue to the leakage is again a vacuum effect that will pull attic air into the duct air stream. The yellow insulation acts as a filter and the brown is a sign that air has been pulling through and there is an open leak on the other side.
Other things we look for besides obvious openings in ductwork is to make sure that all ducting is strapped up properly. Sags in duct systems slow airflow which causes performance issues as well. After a duct test is performed if repairs are necessary but a full replacement is not, we will quote you what we call a wrap, strap, and seal. We are going to go through and do all of the above-mentioned repairs to get the system as buttoned up as possible. We also include a duct test at the end to show you the difference between before and after.
When do you know duct replacement is needed versus a duct repair? Sometimes it is obvious. Flexible ductwork has three components: the inner plastic liner with coil spring, a layer of insulation, and an outer vapor barrier. If the outer barrier is torn (or in some cases completely deteriorated) and the insulation is flopped open and all you see is the clear tube of plastic your air is running through? It is time to replace a duct. If you have had rodent issues where they have been either living, dying, or defecating in the ductwork, it is time to replace the duct. If your home was originally equipped with a furnace only and no air conditioning, the ductwork that was installed is much too small to handle the airflow needed for air conditioning and should be replaced. Even if central air conditioning had already been added at some time along the way, we will know right away if the ducting is adequate to handle modern air conditioning.
If you’d like to schedule an appointment to get your air ducts tested, give us a call at the office at 916-481-0658 or click Perfection Home Systems to contact us.