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Hot
water systems come in two main types, instantaneous and storage. Both
can be suitable for most households, although there are restrictions
on the installation of gas hot water systems indoors. Consult with
your gas system retailer/supplier to ensure the safety of installing
any gas hot water system indoors.
Instantaneous (continuous flow) hot water systems
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Water
is heated as needed and therefore a storage tank is not required,
saving on purchase cost and energy losses. |
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As
water is heated instantaneously, these systems do not run out
of hot water. |
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Their
size is smaller than storage systems and they can be mounted
on a wall or in a cupboard. |
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They
can be installed externally or internally, with restrictions
on internal gas hot water systems. |
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Hot
water is delivered at a slightly reduced pressure. |
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Standard
units can generally deliver adequate hot water to only one tap
at a time. When a second tap is turned on, the pressure and
temperature of the water will drop somewhat. |
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High
powered units are available which can service larger flow rates
and several taps. |
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They
can operate on natural gas, LPG or three phase electricity (single
phase units are very low powered). |
Storage hot water systems
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Hot
water is stored in an insulated tank ready for use throughout
the day. The tank size is important and you should discuss with
your supplier your specific size requirement. |
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If
the tank is too small for the number of people in the house,
hot water can temporarily run out. If the tank is too large,
operating costs will be higher than required. |
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Heat
will be lost from the tank. Losses depend on the temperature
setting, the tank size and insulation of the tank. The smaller
your tank the less your daily tank heat losses will be. |
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Solar
hot water systems use solar thermal collectors (basically black
pipes in an insulated box with a glass lid) to heat the water,
with a booster inside the tank. |
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Other
storage hot water systems have only the one heat source, which
can be an electric element similar to that in a kettle, a heat
pump or a gas or wood burner with a heat exchanger. |
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Heat
pump storage hot water systems use less electricity than electric
element storage hot water systems. They use an electrically
powered compressor and a refrigerant gas to extract heat from
the air (in much the same way as heat is extracted from your
refrigerator) to heat the water stored in the tank. They make
a low noise in operation, similar to a fridge. |
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Mains
pressure or reduced pressure (gravity feed) systems are available.
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