Duct Sealing and Insulating?
On my todo list since we moved into this house 11 months ago was to work on sealing the very leaky ductwork in the basement. When the AC is on, the basement is COLD, main floor right where the thermostat is set, and the upstairs is warm, with my daughter's room getting pretty hot if she doesn't have her blinds closed as she gets the afternoon sun and our bedrooms have massive (~30sqft) windows.
I got a quote for Aeroseal but decided against doing it at $2000, plus I had a heck of a time getting the sales guy to actually show up so I don't really think I want to deal with them. I bought 2 products--a really good foil tape and the mastic you brush on. Last night I tackled the main trunk. I taped all the corner seams and joints. I also taped all of the seams on the plenum above the furnace. I used the mastic at every take-off from the main trunk though there was a couple spots I couldn't get to due to framing, ducts, plumbing, etc. Some joints had gaps around 1/4"x1/4" or larger at each of the 4 corners, plus leakage along the seams and there was massive leakage at most of the takeoffs. It made a HUGE difference in the amount of air movement you can feel in the basement when the fan is running. I wish I'd taken a thermometer down as it felt like the basement temp had risen to match the upstairs by the time I was done--before you could tell a very obvious difference as you walked down the stairs.
I haven't done any sealing on the round ducts that lead from the trunk to every register which general seem to be significantly better than the trunk. Not perfect but it would take a lot of work and a lot of materials to seal all those runs, where I can even reach to do anything with them. Also obviously I can't reach the parts that go into the walls and go up to the second floor (every second floor register is its own run from the basement trunk.) I'm wondering if this is worthwhile? Another thought I had would be to take out as much of the metal runs as I can and replace with the flexible insulated stuff. I'd leave the first elbow off the take-off and the last elbow before the duct goes up into the wall or to a register on the first floor.
Also, the return trunk is similar--any benefit to sealing that? The returns are all wall cavities and they just used a foil covered cardboard product made for that purpose to connect those to the trunk.
Lastly, the main trunk is just sheetmetal. Any payback to insulating it? That looks to be a relatively expensive project unless I can find the material a lot cheaper than Lowes.