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).
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.
