Integrated Heat Pumps

Allied Solar provides a heat pump package integrated with Solar Panels, matching room heat emitters and intelligent controls to provide a lower cost, efficient heating system ideal for new builds.

How heat pumps work

Although it sounds counter intutive, but a bucket of water at 12 °C, can heat a room. By placing it in a freezer, as the bucket of water drops in temperature, the energy taken from it is rejected from the coil at the back, heating the room. The freezer converted the low grade heat energy in the bucket of water into a higher grade heat which heated the room.

The heart of a heat pump is a compressor, similiar to that found in a freezer (only bigger), which extracts energy from the ground or air outside, this then heats water which is pumped into the house heating system.

The magic of heat pumps is because they use free outside energy to start with, the efficiency or coefficient of performance (COP) of the heat pump can be between 300% and 450%. That means for every 1 Kwhr used in electricity to drive the compressor, between 3 and 4.5 kWhrs of heat is extracted. This can make heat pumps very cost effective to use. The smaller the difference between the outside temperature and the temperature that you require to run your heating system, the more efficeintly that the heat pump runs. (i.e. closer to 450%)

Air Source or Ground Source?

Ground source heat pumps work by extracting energy from the ground. The pipes extract heat from up to about a 1/2 metre away, as it does this the temp of the earth around the pipe will become steadily colder as the winter progresses. This can be mitigated to a large extent by increasing the amount of pipe and not burying the pipes too deeply, allowing solar radiation and the heat in rainwater to replenish the energy available for the heat pump to use.

Air Source heat pumps by contrast use the energy contained in the water vapour (humidty) of air. Because the air source uses energy contained in the air, it is replenished immediately. The major advantage of Air Source heat pumps is that no ground loop or bore holes are required. The disadvantage is that they use more electricity during cold weather, and are slightly more expensive than the ground-source types.

Specifically, if a customer has access to a large area (allow 20W/m² for good soils) and can dig the ground loop cheaply, then a ground source heat pump may be the best option. If a customer has a small collector area, or if there are of sharp rocks then an air source could be the best option.

Design tips to reduce your running costs:

• Use the smallest heat pump possible, to ensure fastest response and lowest running cost.
• Use the smallest Domestic Hot Water (DHW) cylinder you can manage with (unless solar panels are also being used).
• Never connect a Heat Pump to a “Dumb” emitter of heat of energy such as Underfloor or Radiators, this will cause a mismatch between the energy source and the use of that energy.
• Keep the delivered heat pump temperature as low as possible.
• If possible, site the heat pump in a bright sunlit (warm) area.
• Use a heating system that is designed with a low thermal mass, for a faster heating response.
• Improve the energy performance of a heat pump, by using a heat emitter that can operate with low water temperatures.
• Use intelligent multi zone water and space heating controls.
• Reduce the Thermal Mass of space to be heated with dry lining etc.
• Eliminate unmanaged fresh air infiltration.
• Insulate, insulate, insulate.