Insulation should be any home-owner's or tenants' priority. Where radiant heat is not contributing to keeping your home warm, the pipes and cylinders should be lagged.

A hot water cylinder without a jacket may keep your airing cupboard warm but it's wasting a great deal of energy. A lagged cylinder will keep a closed cupboard warm more efficiently. If you must have a warmer airing cupboard, don't remove the cylinder jacket; instead, remove a little of the lagging around a hot water pipe. If you ever need to replace a cylinder, buy a pre-insulated one.

If your cylinder is already fitted with a jacket, give it a squeeze or measure its thickness. It used to be thought that a mere 25mm (1 in) thick insulation was enough, but with constant fuel price rises, this is no longer true. If your existing jacket is 'skinny', buy a thicker one. For extra insulation you could even put the second jacket over the first. The costs will be recovered in a few months in fuel savings.

Lagging a Water Cylinder

Cylinder jackets are 'tailored' to fit the size of cylinder and are fitted quickly and easily with retaining straps around the cylinder body. Measure the height and circumference of the cylinder to get the right size - it's better to have a jacket that is a little too big than one that is too small to cover the cylinder completely. Buy a good-quality jacket by looking for the British Standard kite mark (BS 5615). This will ensure that it is made from segments of 80-100mm (3 1/4-4in) thick mineral-fibre insulation wrapped in plastic. Thread the tapered ends of the jacket segments onto a length of string and tie it around the pipe at the top of the cylinder. Arrange the segments evenly around the cylinder and wrap the straps or string around it to hold the segments securely in place. Make sure the edges of the segments butt together tightly and tuck the insulation around pipes and the thermostat.

Lagging Pipes

Cold water pipes in the attic, loft or roof space should be lagged to stop the water in them freezing. Hot water pipes exiting from cylinders should be insulated against expensive heat loss. Mineral-wool bandage wrapped around the pipes and taped or tied at intervals is one of the cheapest ways to insulate pipes. This is fine for lofts and roof spaces where aesthetics are unimportant. A neater and quicker way - although a little more costly - is to cover pipe runs with flexible foam-plastic sections which can be taped together. Most tubes are pre-slit along their length so they can be sprung over and around pipes. The joints between successive lengths are sealed with PVC adhesive tape. Where pipes bend, the tubes are 'nicked' along the slit edges so the tube can be bent without it bunching up and springing off the pipe. At elbows in pipes and at 'T'-joints, neatly fitting joints are made by mitring the ends of the tube or making wedge-shaped butt-joints. The tubing is made to fit different diameters of pipe and varies in thickness from 10-20mm (1/3-3/4in). Some incorporate a metallic foil backing to reflect the heat back into hot water pipes. Check the diameter of the pipes first and measure the runs to calculate which size you require and how much insulation you need to buy.

When working in a loft, make sure you don't stand between the joists as the roof may not support your weight. Make a platform by slinging two or three planks across the joists to distribute your weight evenly.