Insulation ALLWAYS helps but depending on conditions,sometimes more than others. If crawl space has free air flow , duct insulation will help more than if space is sealed and insulated. You can get some indication by going in to check during ambient temprature extremes. If duct surface is more than 30f warmer/cooler than ambient,it need's insulation.

The wider the difference,the more insulation will help.

Does that answer your concerns?

Still wondering which product to use in a confined space. Reflectix seems more doable but not sure if it's the right solution (central California).

I had this project done by an HVAC contractor when new furnace and AC equipment was installed. The first (and perhaps more important) step was to seal all piece to piece connections, junctions and seams with mastic (where accessible) and mastic tape where not accessible. Then, a fiberglass product with a foil face was wrapped around the ducts and sealed.

klem, unless you're talking about a heat pump whose output temp in heating mode may will be less than from a combustion furnace, there's always going to be a 30 deg F or greater difference between air inside a duct and air outside a duct.

Reflective wouldn't help so go by R-value. You might still find the best/least expensive is also reflective. It's amazing how much R-value thin bubble wrap afford's so that's probly what work's best for ypur confined space.

I'm confident the material used by one of the best and busiest contractors in my area was and applied properly.

Elmer J Fudd said,
"I'm confident the material used by one of the best and busiest contractors in my area was and applied properly."

Which doesn't make a lick of sense,,,,,,,,,but what's new? LOL

"Elmer J Fudd said,
"I'm confident the material used by one of the best and busiest contractors in my area was and applied properly."

Which doesn't make a lick of sense,,,,,,,,,but what's new? LOL"

klem, tell me how or why you think you know more than one of the busiest and most highly regarded HVAC contractors in my area. Not necessarily my house as the best example but it's an area with a lot of expensive and upscale houses.

You know better because........?

No response from klem1, I'm not surprised.

Elmer Fudd......Your statement left me without information that would help. What material was used & how was it applied?

I'm sure Elmer's contractor used foil-faced fiberglass - that's the standard. As I said this will not work for me due to the confined space to install. I'm still leaning towards Reflectix. With a 3/4" air gap (a couple wraps of 2" Reflectix) and a single wrap of the pipes with Reflectix they claim R-6 which is fine. If anyone has a better way to go I'd love to hear it.

Yes, badabing. About 1/4 if my "crawlspace" is crawl space (including where the supply plenum is) but the rest is kneel space, standing space, then ladder space because of the slope, and access is through a regular sized door on the low end. I can't say I crawled to the far side to check what they did but I trust it was the same all along.

As I said before, the key opportunity for you, even more important in my opinion than insulation, is to seal all the duct and plenum joints as best you can. If you want some motivation and an objective "opinion" as to whether it's necessary, have a leak test done. I once saw a product being used on This Old House that was an internal sealing aerosol product (kinda like the dreaded Stop Leak that shouldn't be used for car radiators) but it seemed to do the trick. I don't know where you are in Central Calif but I'm near coast. I've never heard of something like that around here but maybe it's available.

Elmer J Fudd4 days ago

last modified: 4 days ago

No response from klem1, I'm not surprised.

Folks don't have time to respond to your drivel because it's not relivant and on topic. No where did I say I know more than any contractor,much less yours. What I said was the statment you wrote make's no sense. "I'm confident the material used by one of the best and busiest contractors in my area was and applied properly." And it doesn't. Then you call me out about "a heat pump whose output temp in heating mode may will be less than from a combustion furnace, there's always going to be a 30 deg F or greater difference between air inside a duct and air outside a duct." I hadn't mentioned any of that. The only time I mentioned air was about temperature relation between exterior of duct and ambient air. Where did you see me say anything about air inside duct? Now slink back to edit after the fact like you are famous for. Just express your opinions and stop challanging mine with your made up nonsense. Unless I'm talking to you it is non of your business and I don't come here to go back and forth with you.

I said I was confident a proper material choice (that I described) had been made, given the reputation and quality of the contractor. You said it didn't make sense, so I inquired politely.

I do not do after the fact editing. You're thinking of someone else or just trying another fatuous attempt at an insult. I'm happy if you make no further comments. Not atypically, I don't think what you said added anything to the conversation.