Heat pump technology might
appear like science fiction to many observers, but in reality this
method of retrieving heat has been with us for decades. More or less
every home these days will have a refrigerator. In short, a fridge
works in much the same way - extracting heat from its interior then
dumping it (This is why it feels warm at the back of a fridge). Heat
pumps work in much the same way, but instead of dumping the
extracted energy it is fed to a compatible cylinder where it heats
water for domestic use.
Heat pumps can obtain heat from
different sources. 'Ground Source' heat pumps, as the name suggests,
capitalise on the store of heat within the ground around us. By
laying lengths of pipe to an appropriate depth ground source heat
can be extracted. Air recovery systems can extract heat from warm
air before it is exhausted from a building.
On its own a heat pump can sometimes
struggle to raise the cylinder temperature much above 50-55oC. For this reason
immersion heaters are used as a supplementary heat source, or the
cylinder can be boosted by using solar energy. Twin coil HP
cylinders are ideal for the latter.
Heat pump and solar cylinders differ from
standard cylinders in so far as heat exchanger technology.
Whilst they utilise heat exchangers, the type used present a much
larger surface area. This is achieved by using radial fins on the
heat exchanger tubing affording better heat transfer. Heat pump
cylinders are available as
coil models for vented or unvented water systems. Please check the
appropriate model for your system.
Outputs from heat pumps and solar
collector arrays vary. You
should refer to the technical specification that accompanies your
particular systems for fuller detail. This information can then be
incorporated to identify the most suitable cylinder setup.
Vented and Unvented. Energy may
be gathered in cylinders that are vented (fed by a gravity cold
water supply) or unvented (fed directly from the cold water main)
according to your household plumbing requirement.
Note: Never attempt
to use a 'vented type' cylinder in an 'unvented system'.
'Unvented type' cylinders are designed to operate at much higher
pressures that their 'vented' counterparts. Failure to observe this
warning can result in explosion, serious damage to property, injury