Homework 2: Duct Sealing

                                        Homework 2: Duct sealing

Since we breezed right through the air sealing mentioned in the previous blog, let’s move on to duct sealing. One of the things that I neglected to mention in the previous post was that some of the processes I am describing for saving energy in your home are based on living in central Georgia. Climates with different humidity levels would certainly be handled somewhat differently, but for duct sealing it’s all one in the same. The more conditioned air you keep in your home and duct system the less your unit will run and the cost to heat and cool will go down.

If you’re anything like me the understanding of how exactly a heat pump air conditions your home is a big mystery. You turn it on, a miracle happens, and cool air comes out of the registers! Really I understand a little more than that, but for duct sealing you don’t need to understand how the magic happens, you simply need the will and a few materials.  A bucket of mastic, 24”zip ties (two for each connection), a razor knife, foil tape (not duct tape!), a bottle of rubbing alcohol and a box of disposable latex gloves. All of which can be purchased for less than $100 at Lowes or Home Depot, but I prefer my local hardware store.

I would be glad to go in great detail about how to seal each and every connection, but really you just remove each connection, clean with alcohol and coat with mastic. If you liked making mud pies as a kid you will have no problem duct sealing. There are some great videos on Youtube.com and wxtvonline.org that will lead you through the process step by step and it is a homeowner friendly job. By sealing your system you will prevent air leakage in to (and out of) your home even when the system is not running.

What you need to think about when doing this job is that the air moving through your duct system is inside the envelope of your home. When you have leaks you are mixing outside (unconditioned) air with the expensive air you have conditioned. When your duct system is in the crawl space you are mixing in damp, potentially moldy air. When it’s in the attic you are mixing in insulation particles and very hot air. And don’t for a minute think this applies only to older homes and systems. 10%-35% leakage in systems that were new or only a few years old is not uncommon; I’ve seen them first hand. To sum it up-If you don’t have mastic on all duct connections you are giving money away! Time to play in the mud!