My house has old (large diameter) steel central heating pipes. These travel through the basement before passing up through the house. My concern is that when they pass through internal walls they are cemented directly into the wall (i.e. they are in tight contact with the brickwork).

My question is - is this normal, or should they be insulated as they pass through the internal brickwork? (I've no idea whether the heat loss in this case is significant or not).

  • I wouldn't worry about the heat loss through a 4 inch section of pipe as it passes through the wall as long as you have all your "open" sections of pipe insulated.
    – ChrisF
    Commented Oct 13, 2011 at 10:34
  • @ChrisF - Thanks. They're about 50% insulated at the moment, I'm in the process of fully insulating them.
    – UpTheCreek
    Commented Oct 13, 2011 at 11:16
  • As the walls are internal, why do you care about heet loss? (the heat will help to heat your come) However I could be thinking about movement when the pipes expand with heat.
    – Walker
    Commented Oct 14, 2011 at 13:26
  • @Walker - Because they go through a number of sections of a cold/unheated basement. Not bothered about expansion though, as the them exp. of steel is less than 2mm/metre at these temps, and they don't seem to have disturbed the walls
    – UpTheCreek
    Commented Oct 14, 2011 at 14:34

1 Answer 1


No disrespect to ChrisF but I disagree fully.

4" of common brick has an R-Value of only 0.88 - so its a pretty good conductor of heat, which isn't what you want when you want to conserve heat. The direct contact with the wall will only improve heat conduction, as well.

UNFORTUNATELY - given the tight space, you aren't going to be able to insulate where you need it most, the point of direct contact.

If you're not averse to a little more elbow grease - your 4" pipe has a 12.5 sq in internal surface area (ie: the area of the circle), so you could replace the round 4" pipe with either fairly small square duct (if you can find it, 3x4 is pretty small) or insulated round pipe. If you go with the square duct, you can go larger than necessary (just don't go smaller) and box it in with Styrofoam board cut to fit to give a good thermal break.

  • 2
    I'm aware that brick isn't a very good insulator ;) I was just pointing out that for the effort involved it probably isn't worth insulating that short section of pipe.
    – ChrisF
    Commented Oct 13, 2011 at 13:12
  • I don't see where the question suggests that the runs are only 4" long except in your comment - though thinking about how the question was phrased, it sounds like the walls being traversed aren't external in which case, I do agree, why bother? Commented Oct 13, 2011 at 13:14
  • Yeah - I assumed that the wall was a single skin of brick/breeze block.
    – ChrisF
    Commented Oct 13, 2011 at 13:21
  • I have GOT to stop posting answers before my 2nd cuppa Commented Oct 13, 2011 at 13:22
  • @TheEvilGreebo - thanks. Regarding your point about them not being external... They're internal, but in a cold basement (which I don't want to heat).
    – UpTheCreek
    Commented Oct 13, 2011 at 15:32

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