Hello All ~ this forum is fantastic and I appreciate all the great info I've already been able to pull out.

I just had my Geo system installed and it became operational in September.  We replaced an oil boiler hot water heat system with ducts for geothermal.  When discussing our options with our contractor (who was great) we decided to NOT have the ducts in the basement insulated.  The old oil boiler put off a lot of heat which in essence "kind of" heated the basement (it is not a finished basement).  We were going to allow the heat lost in the ducts in the basement to do the same.  Anyway, as it gets colder outside I have noticed that the basement is definitely colder.  Another important piece of info is that we have one of those basements where there is a garage door and you pull your car into.  I know that I am losing efficiency because they are not insulated, but am wondering how much colder the basement would be without this heat transfer?

I am embarassed to admit that I don't have those little areas above the foundation on the side walls insulated, furthermore, our VERY old garage door has serious leakage.  So, I'm throwing it out there.... what do you all think about the un-insulated ducts and would it be OK to leave them un-insulated if I tighten up the rest of the basement?

Definitely insulate them.

I understand the idea of not insulating the ducts in order to heat the basement a bit, but by your description it is something of a lost cause.

I'm surprised new ducts passed inspection w/o insulation.

Another issue is cooling - cold uninsulated ducts are likely to 'sweat', that is, condense water out of damp ambient air. This is not only annoying but also a surefire recipe for mold and other indoor air quality problems. Every pest (rodent, insect, etc) needs water to live - why provide it to them in your basement?

hi ona

all ductwork out side of the thermal boundary(your basement/garage) should be insulated

heat transfer from your old oil boiler was fine,from your new geo system its not

i  would still insulate and air seal as best as you can

did you have a bpi energy audit done?

if you do nyserda will contribute a substantial portion you should get something from the state toward your energy conservation measures

good luck
jason

Ask your installing contractor how he loaded the basement in the calcs. If he allowed enough to heat the basement, you may consider insulating and some duct openings. If he calculated correctly, and there is no underfloor insulation, you would find load requirements similar (and therefore energy usage) between ducts in unconditioned space vs conditioning that space.
Joe