are room-sealed appliances (requires no ventilation) in common use, usually requiring 22mm gas
supply pipe, giving continuous hot water to various taps.
are totally independent of any central heating system so can be fitted
in homes without central heating. They can also be used to give instant
hot water with any other type of heating. When a hot tap is turned on,
the burner fires heating the water and delivering it at about 8-10
litres/min (dependent on incoming water supply) for as long as the tap
remains open. Although several taps, showers etc, can be supplied,
realistically water can only adequately flow from one draw off point at
a time. Most instant water heaters do not require any electrical
connection and require no hot water storage facility.
Combination/Conventional/Storage Combination/ Conventional vented or
unvented boiler. See Central Heating section.
Water Storage Cylinders
conventional and pressurised hot water storage cylinders can be heated
either by electricity or any central heating boiler or both
together. They are usually located in an airing cupboard together
with their associated controls, central heating pump etc. See
Central Heating section
flueless appliance giving single point continuous hot water to supply a
single tap or spout. Because these appliances are unflued, siting and
use restrictions apply.
Multi-Point Water Heater
Sink Water Heater