# How to deal with obstruction when insulating pipes?



## Rav (Dec 7, 2011)

I'm insulating hot water heating pipes (black iron pipe) in my basement using 1"-thick-wall jacketed fiberglass tubes. At one point one of the pipes passes right under a 2 foot wide A/C duct. The tube won't fit at the top of the pipe since it's too close to the duct. What's the best way to insulate that section? Do a relief cut that's so deep that there's almost no insulation left at the top, but still retaining the jacket (which would probably deform due to almost no insulation left)? Or cut out a inch or two wide, two foot long section at the top of the pipe? Or ... ? Moving the heating pipe, or moving the A/C duct, is NOT an option. Thanks.


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## Wildie (Jul 23, 2008)

Rav said:


> I'm insulating hot water heating pipes (black iron pipe) in my basement using 1"-thick-wall jacketed fiberglass tubes. At one point one of the pipes passes right under a 2 foot wide A/C duct. The tube won't fit at the top of the pipe since it's too close to the duct. What's the best way to insulate that section? Do a relief cut that's so deep that there's almost no insulation left at the top, but still retaining the jacket (which would probably deform due to almost no insulation left)? Or cut out a inch or two wide, two foot long section at the top of the pipe? Or ... ? Moving the heating pipe, or moving the A/C duct, is NOT an option. Thanks.


Do a relief cut that's so deep that there's almost no insulation left at the top, but still retaining the jacket

There, you answered your own question!


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## TarheelTerp (Jan 6, 2009)

Rav said:


> I'm insulating hot water heating pipes (black iron pipe) in my basement using 1"-thick-wall jacketed fiberglass tubes. At one point one of the pipes passes right under a 2 foot wide A/C duct. The tube won't fit at the top of the pipe since it's too close to the duct.  What's the best way to insulate that section?


If this is an untempered basement...
then the AC duct should be getting insulated as well.
That stuff (R6 duct insulation) is about 1.5" thick.

Somethings got to give.
http://www.youtube.com/watch?v=xAf3FgwPzaI

hth


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## Windows on Wash (Aug 30, 2011)

In this area, 95% likely the basement is conditioned.

While I applaud the goal to insulate the pipes, the reality is that they are not costing that much in lost efficiency. For 1/2 the season (heating season) they are helping condition the space.

I would not leave just the jacket on the insulation if it is PVC jacketed. The fiberglass is what is providing the thermal resistance in this case and PVC against a hot pipe is never a good idea.

I would not be too concerned about the lack of insulation in a few spots.

There is much more potential in the home with the repairs on other items (air sealing the attic, bands, etc).


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