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Insulating return pipe steam heat

mfleck | Posted in General Questions on

hi all,

there is about 15 feet of supply and return pipe for our steam heat system that runs through our unconditioned garage. Out energy auditor recommended insulating these. I insulated the supply pipes using the 3-foot fiberglass tubes with the white paper wrap and adhesive tape included. I was hoping to insulate the return pipes in a way that saves some money and maybe repurposes some materials I have so that I bring less new crap into the world. 

Any creative ideas?  I have a bunch of that reflective bubble wrap lying around that I could make as an outer shell around some fluffier insulating material around the pipe. I have some good tape I could use too.

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  1. tommay | | #1

    I would rather leave them uninsulated. A little heat for the garage and better condensing action. Systems in the past used methods to cool the return lines, whether it be lengthy returns above or on ground level introducing convection and conductive cooling, and of course some still do. So if you have an older system with lengthy returns, they are probably there for a reason. Newer, more efficient systems use less water, for the same result, so there is less water that has to condense and return. So insulating the lines may not be worth it. It may make your system cleaner and more efficient from the flushing action of the condensate.

  2. Expert Member
    BILL WICHERS | | #2

    I’d be careful with the reflective bubble wrap: steam system operating temperaures may be above the recommended operating temperature for that type of insulation. I’d stick with the fiberglass insulation here if you do decide to insulate those runs.


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