The
two main types of hot water systems
available today are storage water
heaters and continuous flow water
heaters, sometimes referred to
as instantaneous water heaters. Both
types are suitable for most households.
However, your decision should
be based on the size of your family,
purchase and installation price, the
unit’s efficiency and running costs, and life expectancy of the unit.
Storage
water heaters
Water
is heated and stored in an insulated tank
ready for use throughout the day. Operate
most economically on solar energy,
natural gas or off-peak electricity. They
can also run on LPG, peak electricity or
solid fuels such as wood or briquettes.
Available
as either:
(a)
Mains pressure: hot water is delivered at
a similar pressure and flow rate as the
cold water. This means that more than
one outlet can be turned on without
affecting supply pressure. Normally
located at ground level, and
can be installed either inside or
outside the home.
(b)
Constant pressure: hot water is delivered
at lower pressure than mains pressure
units. They are normally located
in the roof space of a home, and
the pressure depends on the vertical
distance between the tank and point
of use. Constant pressure units are
often cheaper to purchase and have
much longer life expectancies than
mains pressure systems. Correctly
plumbed, they will provide satisfactory
service. They are also known
as ‘gravity feed’ or ‘low pressure’
systems.
Continuous
Continuous flow (instantaneous) water heaters
Water
is heated only when required and therefore
does not require a storage tank. As
water is heated instantaneously, they
cannot ‘run out’ of hot water. Smaller
in size than storage systems, and
can be installed internally in a cupboard
(gas units must have a flue) or
externally on a wall. Connected
to the mains water supply and
deliver hot water at a slightly reduced
pressure. Standard
units can generally deliver adequate
hot water to one or two points simultaneously. High
powered, high efficiency units can serve
larger households. It
is vital that units are sized according to
the maximum number of hot water outlets
likely to be used simultaneously. Some
units have electronic remote controls
for precise temperature control from
inside the house. Remote
control systems that deliver a
preset volume of hot water are also
available. Operate
most economically on natural gas,
but can also use LPG and peak rate electricity. Gas
units generally require a larger gas
supply line than storage systems, potentially
increasing installation costs.
