Furnace Duct Sealing
Dave Stoinski of Best Informed Home Inspections, LLC shared the following tips.
Sealing up your furnace ducts is a simple task that can save you money on your utility bill and make your house more comfortable. You don’t have to take my word for it, most of the facts came from Wisconsin Department of Energy.
(This does not require a professional or a hazmat suit)
You can save 6-7% on your utility bill just by sealing up the ductwork on your forced air furnace and I have seen savings of up to 10% on some applications. This is a job that almost any person can do in an afternoon with a minimum amount of materials. Let’s get started with a list of materials;
1)Dust rags or a shop vac to remove heavy dust on ductwork
2)Long thin incense sticks, your favorite flavor
3)1 Roll – Foil tape, the shiny stuff, never use duct tape it will fall off (rubber-based adhesive will dry out soon).
4)1 Tube – Clear silicone caulk with caulk gun.
5)1 Tub – Mastic sealer. It is in most stores, but you must look for it.
6)Thin rubber or latex gloves and an inexpensive pair of cotton gloves.
All these items should be available for less than $50.00
Now let’s begin.
1)Dust off the furnace and ductwork so the materials will stick better and it won’t be falling in your eyes and down your throat.
2)Go to the thermostat and turn the fan switch from Auto to On
3)Now the fun part! Light the incense stick and move it around the furnace and all the ductwork that is exposed. If the smoke is blown away it is a supply duct leak. If it is sucked in it is a return air duct leak . Seal up as many leaks as possible, the more you seal the better off you are and the more efficient your furnace will run. 4)Now what material should I use and where? Simple answer is whatever works best in that particular spot of the system. Any long straight shot the tape works the best, if a return duct is run between two wood joist the silicone caulk will work the best to seal the sheet metal to the wood. If your ductwork has a long rectangular metal run (it is called the main trunk) it will have elbows coming off the top to direct the air flow to individual rooms in the house. It is very close to the basement ceiling so you can’t get a caulk gun up there and it is too hard to cut pieces of tape to seal up the elbow and I can guarantee that it leaks without looking at it , this is where the Mastic is used.
5)Put on the rubber glove and then the cotton glove, dig into the tub of mastic and get some fingers full of it. Smear it around the seams of the elbow. Just work by feel because it is in a difficult area to see. The Mastic will cure in several days and once cured it is permanent. You can use the Mastic for all the ductwork, but it does look a bit messy if you do it that way. The choice of what material you use where is up to you, whatever is easiest to use.
Once done with the proper materials and with some care you will only have to do this once and it will last the life of the furnace and ductwork.
CAUTION – IF YOUR DUCT WORK HAS A WHITE CLOTH LOOKING WRAP IT MAY CONTAIN ASBESTOS. PLEASE CALL A PROFESSIONAL FOR ADVICE ON HOW TO SEAL IT PROPERLY.
FOR MORE INFORMATION ON ASBESTOS CLICK THE LINK BELOW
Dave Stoinski Best Informed Home Inspection LLC 920 810-4145