Hot Water Pipe Insulation

What this is

Every metre of uninsulated hot pipe between the cylinder or boiler and the tap gives its heat to the space it passes through. Foam or mineral wool sleeving closes that path. It is one of the smallest jobs in this catalogue and one of the easiest to finish in an afternoon, because the pipe runs that matter most are usually the first few metres and they are usually the ones you can reach.

Telling whether your home needs it

Look in the airing cupboard, under the sink, in the loft and along any pipe crossing a garage or crawl space. Bare copper is the thing to look for. A cupboard that stays warm when nothing is running, or a long wait for hot water at a tap that is not far from the cylinder, both indicate heat being lost on the way.

What the job involves

Measure the outside diameter of the pipe and buy sleeving to match, not by guesswork. Split sleeving opens along a seam, goes over the pipe and closes with its own adhesive strip or with tape. Cut mitres at elbows so the two lengths meet without a gap, and butt joints tightly along straight runs. Bends, valves and the first metre out of the cylinder are the places worth taking care over.

Things to watch

In unheated spaces the same sleeving reduces freeze risk on cold pipes, so it is worth doing both while you are there. Do not cover pipe near a flue or any surface that gets hot with a material not rated for it. Leave stopcocks and isolating valves accessible rather than sleeving straight over them.