How to Insulate a Hot Water Cylinder
Insulating a Hot Water Cylinder
Many people think that an unlagged cylinder has the advantage of providing a useful source of heat in an airing cupboard — but in fact it squanders a surprising amount of energy. Even a lagged cylinder should provide ample heat in an enclosed airing cupboard; if not, an uninsulated pipe will do so.
Choosing the jacket
Proprietary water-cylinder jackets are made from segments of mineral-fibre insulation, 80 to 100mm (3-¼ to 4in) thick, wrapped in plastic. Measure the approximate height and circumference of the cylinder to choose the right size. If need be, buy a jacket that is too large, rather than one that is too small. Make sure the quality is adequate by checking that it is marked with the British Standard kite mark (BS 5615).
Fitting the jacket
Thread the tapered ends of the jacket segments onto a length of string and tie it round the pipe at the top of the cylinder. Distribute the segments evenly around the cylinder and wrap the straps or tapes provided around it to hold the jacket in place. Spread out the segments to make sure the edges are butted together, and tuck the insulation around the pipes and the cylinder thermostat.
If you should ever have to replace the cylinder itself, consider substituting a preinsulated version, of which there are various types on the market.
It is also a good idea to insulate hot-water pipes in those parts of the house where their radiant heat is not contributing to the warmth of the rooms.
Lagging a hot-water cylinder
Fit a jacket snugly around the cylinder and wrap foamed-plastic tubes around the pipework, especially the vent pipe directly above the cylinder.
Lagging pipes with foamed-plastic tubes
- Most tubes are pre-slit along their length so that they can be sprung over the pipe. Butt successive lengths of foam tube end-to-end, and seal the joints with PVC tape.
- At a bend, cut small segments out of the split edge so that the tube will bend without crimping. Fit it around the pipe and seal the closed joints with tape.
- Where two pipes are joined with an elbow fitting, mitre the ends of the two lengths of tube, butt them together and seal with tape.
- Cut lengths of tube to fit snugly around a , linking them with a wedge-shaped butt joint, and seal with tape as before.
Lagging Your Pipes
When water in a plumbing system is allowed to freeze, it expands and sometimes splits the wall of the pipe or forces a joint apart, with the result that water pours into the house as soon as the ice melts. It therefore pays to insulate cold-water pipes in unheated areas of the building.
Choosing insulation for pipes
You can wrap pipework in lagging bandages (there are several types, some of which are self-), but it is generally more convenient to use foamed-plastic tubes designed for the purpose. This is especially true for pipes close to a wall, which may be awkward to wrap.
Foamed-plastic tubes are made in sizes to fit pipes of various diameters: the tube walls vary in thickness from 12 to 20mm (½ to 3/4in). More expensive varieties incorporate a metallic-foil backing that reflects some of the heat back into hot-water pipes.