Air Source Heat Pumps
What is an Air Source Heat Pump?
If space is at a premium, ground type not suitable or costs associated with a ground source heat pump are not viable, then the next best option is to consider an Air Source Heat Pump (ASHP). These work in a similar fashion to GSHP albeit collecting heat from the atmosphere rather than the ground.
How does an Air Source Heat Pump work?
An air source heat pump works with the use of a fan which pulls air through the body of the unit, passing through a heat exchanger lattice contain a super chilled refrigerant gas (the evaporator). When the warmer air passes over these fins, the gas’ temperature rises, enough to boil it in fact. This temperature rise is increased further with the use of a compressor within the heat-pump. This heat is then passed through a heat exchanger and this is used to bump the water/glycol circuit for heating and domestic use up to 75°C. As with all heat-pumps, this then passes through an oversized coil within a cylinder for hot water or run around your central heating system.
Are they efficient?
ASHP will still produce an average of 3 times more heat than energy consumed, though not quite as good as a ground source heat pump – mostly owing to the fact that the air temperature fluctuates more than the ground meaning the heat-pump has to work a little harder when it gets really really cold. They are much more cost effective to run compared to oil or LPG gas boilers.
Renewable Heat Incentive
The Renewable Heat Incentive or RHI that air source technology attracts is designed to offset the increase outlay verses a more conventional fossil fuel fired system.
Currently, the tariff rate for new air source installations is 10.49p/kWh* for domestic installations with an upper limit of 20000kWh for deemed water and space heating combined. If your property's EPC figure is higher than this payments are simply throttled back to this figure.
Below is an example of what this equates to in terms income for a standard 3-4 bed detached property;
Property size = 200m²
Property age = 1980’s
Property insulation standard = filled cavity and required 250mm of loft insulation
Payment per quarter = £375
Payment over 7-years = £10,500 (excludes year on year inflation percentages)
* Tariff rate taken from Ofgem with the rate running from 1st April until 30th June 2018.