What are the benefits?
The core benefits of an air source heat pump is a more energy efficient method of heating your home, and therefore lower heating bills and carbon emissions. According to heat pump supplier Nu-Heat, for every unit of energy an air source heat pump uses to extract heat from the air, it outputs three times as much into your home.
There are savings to be made in your home’s carbon footprint too, as even in replacing an A-rated gas boiler, you’ll save between 2,150 to 2,250 kg of carbon a year, according to the Energy Saving Trust.
Compared to ground source heat pumps, air source pumps are relatively easy to install, around two-thirds of the cost and don’t require a great amount of outdoor space. This makes it a superior option for retrofitting to the majority of homes.
“One of the key considerations for low-carbon technology is how likely it is to go wrong,” says architect Mark Elton of retrofit specialists Cowan Architects. “Heat pumps have been around for a long time. They’re not much different to your fridge, and we know that fridges don’t tend to go wrong.”
Mitsubishi’s Ultra Quiet Ecodan air source heat pump virtually eliminates the need for considering noise as part of planning permission
Will an air source heat pump work for my home?
Air source heat pumps offer an alternative for traditional gas boilers, however, they’re best used in airtight, well-insulated homes. This is because they work best at producing heat at lower temperatures than boilers, so ensuring that your home is draught proof will up its efficiency.
“We need to look at a fabric first approach,” explains Mark. “If you spend a lot of money on a heating source for your poorly insulated building, that’s probably your wrong priority. If you do something in the future that does reduce the demand of space heating dramatically, you may have wasted that investment on an oversized heating system.”
An air source heat pump draws heat from the outside air, so when the outside temperature is lower, its efficiency levels decrease as it requires more power to increase the temperature of the trapped heat. If you lived in a very cold climate, the case would be better made for a ground source heat pump which draws relatively steady heat from the ground. However, with an optimum operating temperature of 7°C, this shouldn’t be too much of a concern for the majority of homes in England, where the Green Homes Grant applies.
Because air source heat pumps work at lower temperatures, they’re a good match with underfloor heating and low-flow radiators. You may need to replace some, or all, of your radiators if upgrading to a heat pump.
There is also the option of a hybrid air source heat pump. This heat pump works in partnership with a gas boiler to meet any shortfall in efficiency on the part of the heat pump. While the majority of your hot water and heating needs would be met by the heat pump, however if heating demand is high and the outside temperature is not, the gas boiler kicks in to contribute to the heating mix.
However there are some potential drawbacks to air source heat pumps. Because of the lower temperature produced, it can affect the maximum tap water temperature your home can achieve. Some air source heat pumps can still be noisy too, though technology on this front has improved in recent years.
Heat pump installer Nu-Heat uses NIBE air source heat pump for heating and hot water
How much does it cost?
According to quote comparison site Green Match, the average price for installation of an air source heat pump is between £8,000 and £18,000 for an air-to-air source heat pump and £7,000 and £11,000 for an air-to-water source heat pump, dependent on the size of your home, whether it’s a new build or renovation and the pump brand, size and performance/efficiency.
In terms of running costs, an air source heat pump may actually increase your annual bills, compared to an A-rated gas boiler. According to figures from the Energy Saving Trust, you may spend £95-£100 extra a year to run an air source heat pump.
Estimates from Green Match found that, for an average four bedroom house with an air source heat pump, annual heating costs start from £759 per year, with RHI payback of up to £1,600 per year. This is an estimation, based on an air to water heat pump with 3.7 SCOP and a household with good quality insulation, an average UK electricity price of 14.37p/kWh and an RHI tariff for Air Source Heat Pumps of 10.71p.
At present, the benefits for going green with your home heating are only increasing, and with the likes of Good Energy’s UK-first heat pump tariff, which offers favourable rates for households with higher electricity usage with heat pumps installed, there’s the potential for even greater savings to be made.
The eligible products list is exactly the same as the for the Domestic Renewable Heat Incentive scheme; all products must be listed in the MCS product directory.
Viessman’s Vitocal 100-A air source heat pump is A+++ rated, and can achieve temperatures of 60°C at an outside temperature of -5°C
Installation and maintenance
An air source heat pump is usually made up of both an indoor and outdoor unit. This means you’ll need an outdoor space for the heat pump to be placed – one that has a good air flow is essential, while a sunny spot will help your heat pump run more efficiently when the sun is out. The indoor unit usually isn’t much bigger than a standard boiler system.
At present, in England and Scotland, installation of a heat pump is covered under Permitted Development Rights if it meets a series of criteria, which include keep heat pumps one metre away from property boundaries and ensuring placement minimises the effect on the appearance of the building. You can read more on the Planning Portal.
With regular maintenance and servicing, you can expect an air source heat pump to last for up to 20 years according to the Energy Saving Trust. When purchasing, enquire about the length of warranty and workmanship warranty – the former is often 2-3 years, while the latter can be up to 10 years.