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What is an ASHP

Air source heat pumps absorb heat energy from the outside air to heat homes and offices. There are two types of air-source heating systems. Air-to-air systems provide warm air, which is circulated to heat the building. This has been around for many years and is the basis of most heating/cooling air conditioning systems.

The other type, air-to-water, is based on the same technology but exchanges its heat energy into the water that is circulated around your home through radiator, fan coil and underfloor heating emitters. The seasonal Co-efficient of Performance (sCoP) of these systems start at 3:1! That means for every kilowatt of electrical input, you get upwards of three kilowatts of heat output! They work in ambient temperatures down to as low as -20°C and can provide heat outputs up to 80°C (as hot as a conventional boiler!). Please see the more detailed explanation below:

The Basics

It all starts with the sun. The sun warms up our atmosphere and the outer layer of the earth’s crust. In one year the energy sent to the earth by the sun is 50 times higher than the total consumption of energy on our planet. This makes the sun a vast and inexhaustible source of energy.  On sunny days you can feel the thermal energy from the sun on your skin. But actually, there is always lots of thermal energy in the air, even on cold winter days or even at  night. And not only in Florida or the south of Spain, but also in countries like Sweden or Norway where thousands of houses already have heat pumps.


How do heat pumps work?

A heat pump only needs a heat source (the outside air), two heat exchangers (one to absorb and another one to release heat) and a relatively small amount of drive energy to keep the system going.  A heat pump extracts thermal energy from the environment.  In the case of an ASHP the source is the outside air. The pump extracts the energy at a certain temperature, increases that temperature and then releases it into a medium which in the ASHP system is the water running to your low temperature radiators (or standard radiators sized at a lower flow temperature), under floor heating system or fan coil units. Between those two media the heat is moved by means of a working fluid.

Compressor - the essence of heat pumps

As the working fluid passes through the evaporator and extracts heat from the air, it turns into a gas. This is where the compressor comes in. When you compress a gas the temperature rises. (for example if you inflate the tyre of your bicycle, you can feel the air inside warming up through the rubber).  Inside your house the second heat exchange takes place when the compressed gas enters the condenser, a surface which is colder than the gas itself. Finally, the gas condenses and releases its heat – this heat then warms up your house.

Less energy, pleasant warmth in the home

ASHP systems heat up to 5 times more efficiently than a traditional heating system based on fossil fuels or electricity. By making use of the heat in the outside air, you use much less energy while still enjoying a stable and pleasant level of comfort.

This is NOT a new technology, it has been around for many decades, it has simply been refined to suit every type of home in the UK