Hot water service using high-efficiency gas-fired appliances†

Smnmary Research on boilers used for heating systems has been extensive but less attention has been paid in the past to hot water appliances. Improved boiler performance, higher insulation of buildings and increased adventitious gains have meant that energy use for the supply of hot water has become more significant. Field and laboratory studies have therefore been carried out to investigate the performance of recently available high-efficiency gas-fired water heaters. A field study of a plate heat exchanger used in conjunction with a high-efficiency boiler was also undertaken to gain some knowledge of an alternative method of supplying hot water. The results obtained show that changes to the existing system at the field trial site reduced running costs considerably and improved control of the delivered water temperature. Gas-fired appliances with heat transfer efficiencies of up to 94% are now available for the supply of hot water to commercial premises.