insulating HVAC ducts

[iron]

with my basement remodel underway, i have most of the ceiling drywall removed (will be all of it soon). i had originally planned to leave the drywall and the framing around the HVAC ducts alone since i saw no point in redoing it.

it later occurred to me that i have briefly read about why it's important to insulate your ducts. i've always questioned this logic, but assume people do it for a reason.

so, is it worth it for me to insulate this stuff? i would be able to access about 1/2 of the house's ducts with my basement project. the other half is in the garage.

we are planning to heat with wood as our primary source, but it'll be our first year being full-time, so i'm not sure how much supplemental heat we'll opt for. in general, it seems like our heating bills have been reasonable. it's a 2 story house (basement and main floor). we don't use the AC since we're in the pacific northwest and it's just not needed.

right now, i have all of my supply vent lines exposed and those would be easy to insulate (especially since i have leftover insulation from some walls i demolished). the main trunkline is currently still wrapped in drywall.

thanks

 

[heat seeker]

When my central AC was being installed, the installer said it was unnecessary to insulate ductwork in conditioned spaces. I have several closets that have ductwork passing through. None of them has sweated in 10 years. I would think any heat that escaped your ductwork would just heat the floor above, so the heat's not lost. YMMV.

 

[iron]

When my central AC was being installed, the installer said it was unnecessary to insulate ductwork in conditioned spaces. I have several closets that have ductwork passing through. None of them has sweated in 10 years. I would think any heat that escaped your ductwork would just heat the floor above, so the heat's not lost. YMMV.

thanks. that's always been my assumption for what would happen as well. i could see a crawlspace being different.

 

[sportbikerider78]

When my central AC was being installed, the installer said it was unnecessary to insulate ductwork in conditioned spaces. I have several closets that have ductwork passing through. None of them has sweated in 10 years. I would think any heat that escaped your ductwork would just heat the floor above, so the heat's not lost. YMMV.

This. When the humidity of the space the ductwork goes through is high, you get sweat. Insulating helps/prevents that.

 

[heat seeker]

That's why the tech specified "conditioned spaces".

 

[begreen]

It all depends on the heat loss that is tolerable to the "conditioned" space. Our crawlspace is fully insulated and stays around 60F, but we have heat pump ducting running through it. Heat pumps work at lower duct temps than furnaces so keeping heat losses to a minimum is important. All ducting, supplies and return are joint sealed and insulated. The end result is greater efficiency and minimal cold air blowing up into the house from the ducts on startup.

 

[Lake Girl]

You mentioned some ductwork in the garage ... currently insulated?

 

[lml999]

If you have the opportunity, why not insulate. You will get some minor loss in conditioning those enclosed spaces. Why not use that to condition living space?

Payoff will be rather lengthy, but...

 

[iron]

You mentioned some ductwork in the garage ... currently insulated?

ductwork in the garage is covered by drywall - drywall that i am not planning on removing (unlike the basement, which is fully exposed). i think i will opt to not insulate these conditioned space ducts, especially considering we will be heating primarily with the fireplace and the ducts will serve primarily to recirc air.

 

[begreen]

ductwork in the garage is covered by drywall - drywall that i am not planning on removing (unlike the basement, which is fully exposed). i think i will opt to not insulate these conditioned space ducts, especially considering we will be heating primarily with the fireplace and the ducts will serve primarily to recirc air.

If the ducts are lossy they will be recirculating much cooler room air and could cool it down to below room temp. This is why using the hvac system to distribute air doesn't work in some houses.