# Insulating hot water heating pipes, how to "finish" at reduction point?



## Rav (Dec 7, 2011)

I'm not sure if this question belongs in this forum or the HVAC forum, but here goes. I'm insulating my unfinished, unconditioned basement hot water (not steam) heating pipes. I'm using 1"-thick-wall jacketed fiberglass tubes. At one point, the 2" IPS black pipe reduces to 1-1/2" IPS pipe. So of course I'm using a wider diameter fiberglass tube on the wider pipe, and narrower diameter tube on the narrower pipe. At the point where the narrower diameter fiberglass tube butts up against the wider diameter tube, it leaves a visible (i.e. unsealed) area since the narrower tube is, well, narrower. The question is, at least from an aesthetic point of view (if for no other reason), how do I finish that area so the raw fiberglass end of the wider tube isn't visible? I have fiberglass tape that I'm using to seal the butted ends of the same-size tubes, but since these are different diameters that won't work, right? I'm sure that some people just leave it that way, but is there a proper way to finish it? Thanks.


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## Windows on Wash (Aug 30, 2011)

Are you sure the basement is unconditioned? If it is truly unconditioned, you should have some vents much like a vented crawlspace.


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## Rav (Dec 7, 2011)

If I'm using the term "unconditioned" improperly, I'd be glad to learn what it means -- that's what I'm here for, to learn. What I meant was, a space where heating and cooling is not _intentionally_ supplied. There are no vents in the basement that I'm aware of (the house was built in 1931). Two walls of my basement are totally underground, and two are partially so. So I would expect the temperature there not to get TOO cold in the winter or too hot in the summer, even if there were no heat (or cold) source at all. However, the black hot water heating pipes running near the basement ceiling give off a LOT of heat. When it's 67 upstairs (where we live), it can be 70 in the basement, and we spend hardly any time there. So, at this point, I am insulating the main lines (largest diameter pipes). I've almost finished the main supply line, and I'm planning to also do the main return line. I was not planning on insulating the branches at this point, until I see how much cooler it gets (and the branches have a lot more bends, which I now know are a pain to insulate). I can always do them later. We also recently had the basement (and attic) air sealed. The point of all this is to reduce the heat loss in the basement, preserving it for upstairs where we live, and save some heating costs.


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## EvilNCarnate (Jan 27, 2011)

I always just use tape at my joints and couplers, obviously i mean insulated tape, but I just start at the joining edged and wrap back about 2" on the smaller pipe, then I build that up going back towards the joint. This way you end up with 2 layers of tape on the first 2" of the smaller pipes insulation and then typically if its a normal reduction you can wrap right over to the larger pipe.


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## joecaption (Nov 30, 2011)

If the pipes are now insulated how is the loss heat going to help heat the floors anymore, and keep the plumbing below the floors from freezing?


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## Rav (Dec 7, 2011)

Do mean tape such as this:

http://www.grainger.com/Grainger/OWENS-CORNING-Pipe-Insulation-Tape-4LFJ2

That's what I've been using to seal the butt ends between two same-sized tubes.


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## Rav (Dec 7, 2011)

joecaption said:


> If the pipes are now insulated how is the loss heat going to help heat the floors anymore, and keep the plumbing below the floors from freezing?


As I mentioned in a reply a little while ago (you may not have seen it yet), two walls of the basement are totally underground, and two are partially so, which would moderate temperature extremes. And at this point I'm only planning to insulate the main lines, not the branches which give off a fair amount of heat themselves and are a fair number of, to see how much cooler it gets before I even consider doing the branches. I certainly want to leave enough heat to keep the basement significantly above freezing (50s would be fine with me).


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## TarheelTerp (Jan 6, 2009)

Rav said:


> ...at this point I'm only planning to insulate the main lines
> ...want to leave enough heat to keep the basement significantly above freezing (50s would be fine with me).


What is the temperature in there now?
Most cellars will hold 45-50F without any help assuming no actual cold is entering the space. To that end... the portion of the two walls that are partially exposed to wind (above grade)... as well as any actual gaps (cracks, windows, doors etc) that allow cold air in will be a better use of your time, effort and expense.

At summer time though... the AC duct still warrants insulating.

hth


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## Rav (Dec 7, 2011)

TarheelTerp said:


> What is the temperature in there now?
> Most cellars will hold 45-50F without any help assuming no actual cold is entering the space. To that end... the portion of the two walls that are partially exposed to wind (above grade)... as well as any actual gaps (cracks, windows, doors etc) that allow cold air in will be a better use of your time, effort and expense.
> 
> At summer time though... the AC duct still warrants insulating.
> ...


The temp down there right now is 66 (it's 70 upstairs). The windows are new and energy-efficient. And we already have scheduled in a week or so to have any gaps and cracks in all the basement walls sealed (and then DryLok'd). Thanks for your recommendations.


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## Windows on Wash (Aug 30, 2011)

The space is inside the conditioned zone regardless of the supply side of air.

I would not bother with the insulation wrap first and spend the time and effort on air sealing the ribbon boards. You will be more bang for you buck there.


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## stickjim (Feb 24, 2012)

tape the end flat over lapping about 1 inch. Cut overlap into tabs ,fold down on insulation and the tape around the pipe


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## Rav (Dec 7, 2011)

stickjim said:


> tape the end flat over lapping about 1 inch. Cut overlap into tabs ,fold down on insulation and the tape around the pipe


Thanks, stickjim. I should have followed up previously that someone outside the forum recommended using inline reducer covers, which is what I did (I got them from Speedline), and that worked very well. Thanks for your reply.


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