If the plumbing system in your home is not adequately protected, severe weather can cause water to freeze in the pipes, producing blockages and burst pipes. You can deal with these yourself, but it is better to prevent any damage by checking your anti-frost defences every autumn.
Protecting plumbing
Frost protection is built into the structure of a well designed, modern home and the important design points are explained be1ow.
Service pipe
This pipe conveys water from the water authority’s communication pipe to the house and should be covered by at least 750mm of earth throughout its length. If it enters the house by a hollow, boarded floor, it should be thoroughly protected from draughts. The pipe should be taken up into the roof space to supply the cold water storage cistern – against an external wall.
Storage cistern
The cold water storage cistern is best situated against a flue which is in constant use. To prevent icy draughts blowing up the warning pipe leading from the cistern. you can fit a hinged copper flap over the outlet; there is, however, a risk that this will jam in the open or closed position. A better method is to extend the pipe within the cistern and bend it over so its outlet is about 38mm below the surface of the water. There are gadgets, such as the frost guard, which make it easy to extend internally the warning pipe from a storage or flushing cistern. The boiler. hot water storage cylinder and cold water storage cistern are best installed in a vertical column so the vulnerable cold water cistern receives the benefit of the rising warm air. All lengths of water pipe within the roof space should be kept short and well away from the eaves.
Lagging
Efficient lagging of storage tanks and pipes reduces the rate at which water loses its warmth and protects pipes exposed to cold air; but it cannot make up for a bad plumbing design and it will not add heat to the system. Pipes to lag are those against external walls, under the ground floor and in the roof space. Don’t omit the vent pipe of the hot water system since the water in this pipe is not as hot as that in the rest of the system and, if it freezes, it can create a vacuum which could damage the cylinder. There are several types of pipe lagging available and it is best to use inorganic materials. These include wrap-round glass fibre; moulded polystyrene (which comes in rigid sections which fit round the pipe) and flexible moulded foam plastic (which you split open to fit round the pipe).
Polystyrene is rather awkward to use, but is good for underground pipes since it does not absorb water. The moulded types of lagging come in a variety of sizes to fit different pipes. so make sure you buy the appropriate size. Whichever type you use. make sure you lag behind pipes against external walls to protect them from the cold wall. Cover the tails of ball valves and all but the handles of stopcocks and gate valves; if you are using rigid lagging sections, you will need some of the wrap-round type for these areas. Bind wrap-round insulation round the pipe like a bandage, overlapping it to prevent gaps, and secure it with string or adhesive tape. Where a pipe joins a cistern, make a full turn and tie it to hold the end in place. When joining two lengths overlap and tie securely. If you lag the pipes before fitting them there is of course no need to slit the lagging: you can slide the pipe length through it. Where pipes go through a wall make sure the insulation goes right up the wall.
You also need to protect the cold water cistern. The easiest way to cover a square cistern is to use fire proof insulation slabs. For a circular cistern use glass fibre tank wrap. If you have insulating material between the floor joists in the loft, make sure the area immediately below the tank is left uncovered so warn air is allowed to reach the tank’