The hot water system in a house depends on the quantity of hot water required. Based on requirement one of the following methods or a combination may be adopted for hot water generation:
- Instantaneous electric water heaters.
- Storage type electric water heaters (low pressure and high pressure)
- Gas-fired instantaneous water heaters
- Gas fired storage water heaters
- Solar hot water systems
In hot water piping system, there is a possibility that the high pressure water will force itself into the lower pressure supply system when the mixing faucet is opened to both supplies, hence the pressures of the hot water and the cold water should be made equal at each fixture. This can be reduced by use of larger and smoother pipes and long radius fittings in the hot water lines.
Pipes for hot water supply system should not corrode and be suitable for the water pressure, flow rate and temperature of water they will be carrying.
Following points should be kept in mind for selection of pipes for hot water:
- It should sustain in expected temperatures and pressures.
- There should be no electrolytic corrosion.
- It should withstand UV effects (if used outdoors).
Keeping the above points in mind common pipes for hot water supply are:
- Polybutylene (PB)
- Chlorinated Polyvinyl Chloride (CPVC or PVC)
- Random Polyproylene (PP-R)
- Cross linked Polyethylene (PEX)
Whatever the pipe material is, the first meter of length of pipe from water heaters should be in copper.