When a loft is insulated it becomes vital properly to insulate exposed water pipes and storage cisterns, as these will be more liable to freezing. At the same time it is wise to check the thickness of insulation around the hot water cylinder where a lot of heat can be wasted. A new jacket can pay for itself in a matter of weeks.
Hot water cylinder
Pre-lagged hot water cylinders offer a substantial fuel saving over the conventionally lagged type, so if you are fitting a new or replacement cylinder, buy the former. To lag a conventional cylinder, the jacket should be at least 80mm thick to conform with British Standard 5615:1978. Measure the height and diameter of the cylinder to make sure the correct size jacket is bought. Simply clip the jacket around the draw-off pipe at the top of the cylinder letting the segments drape around the sides. Lightly hold the jacket in place by fastening two tapes around the cylinder.
All exposed water pipes in a loft should be insulated, including overflow pipes and the expansion pipes of heating systems.
Pipes close to the loft floor should be covered by the loft insulation. Other pipes should be individually lagged, particularly bends where freezing often occurs first.
The best material is moulded foam pipe insulation. This is split down one side so it can be slipped over the pipe and secured with adhesive tape or string.
The older type paper-backed insulating pipe wrap is wound around the pipe spirally like a bandage and held in place with string.
Keep draughts out of overflow pipes by taping a flap of polythene tubing over the end of the pipe.
Cold water storage cistern insulation
Make sure that loft insulation is not taken under the cistern so that a little warmed air can rise from below.
The cistern must be fitted with a lid to support the insulation and to keep out dirt. The lid will be subject to a lot of condensation, so use an impervious material, such as a slab of expanded polystyrene or plastic tray if a purpose-made lid is not available. Wood is not usually suitable unless it is wrapped in a double thickness of heavy gauge polythene held in place with adhesive tape.
The simplest form of cistern insulation is insulating matting, draped over the cistern and held in place with loops of string around the sides.
Another method is to use slabs of expanded polystyrene at least 25mm thick, cut to fit around the sides and top of the cistern and held in place with meat skewers or cocktail sticks.
Loose fill insulation can be used for cistern insulation by making a simple box around the cistern, and a little larger than it. The loose fill can then be tipped into the cavity. The lid can be a slab of expanded polystyrene, or a tray filled with loose fill with a hardboard lid.