Stainless steel was used in the 1970s for central heating system when copper was expensive. Sizes of stainless-steel pipe are the same as copper 15mm, 22mm and 28mm. It can be cut with a hacksaw or pipe cutting tool and bent with a bending machine. It is easier to make joints in stainless-steel pipe with compression fit¬tings rather than with capillary fittings.
There are three types of plastic pipe avail¬able for use as hot and cold water pipes inside houses:
• flexible polybutylene ('Acorn')
• semi-flexible cross-linked polyethylene ('Pipex')
• rigid CPVC ("Hunter Genova').
Pipex and Hunter Genova come in lengths of 2m and 3m; Acorn also comes in much longer rolls, which makes it cheaper to use as fittings can often be dis¬pensed with on long runs.
Both Acorn and Pipex can be cut with a sharp knife or a special secateur-type cutter; they are joined either with plastic push-fit fittings (expensive) or by using normal compression fittings with a metal insert to support the pipe. Both can be bent around gentle curves.
Hunter Genova pipe cannot be bent around curves and needs a hacksaw or pipe cutter to cut it. It is joined with special fittings using solvent-weld cement. Although these are cheap and fairly easy to use, adequate ventilation is vital as the cement gives off strong fumes and the joint needs to be left before the pipe is used.
For running pipes outside, medium-density polythene pipe (coloured blue) is used. This is joined with special brass compression fittings avoid having any joints under ground.
When buying your plumbing goods:
• decide on the material
Nowadays, cop¬per is the natural choice, but for large jobs plastics could work out cheaper. Con¬sider using flexible plastic pipe for long twisting runs inside houses
• plan the system
Always plan to use the fewest fittings and try to stick to simple couplers and tees
• shop around for prices
List the materials you need and try a number of do-it-yourself superstores prices can vary a lot. For more unusual fittings, you may need to go to a plumbers' merchants