Air source heat pump technology rose in prominence in the 2010s in the UK, with the help of the Renewable Heat Incentive (RHI) – a subsidy paying for the low carbon heating generated to the improver, incentivising the take-up. Now in the 2020s the UK Government is looking to update the heating regulations to further accelerate the take-up of low carbon heating in exchange for the current gas boiler network. 

Here we look at ten things to consider when deciding to purchase the air source heat pump for your home.

Installation cost consideration of Air Source Heat Pumps

Prior to installing what can ultimately be an expensive Air Source Heat Pump, ensure you have sufficiently insulated your house (see Solid or Cavity Wall Insulation, Loft Insulation, Floor Insulation), as otherwise the heat generated is not going to be efficiently used to heat your house. Insulation takes the heating demand down for your property, which allows ASHPs to be effective, given their low flow temperatures.

Buy certified MCS products and services

Only buy Air Source Heat Pumps certified under the Microgeneration Scheme or the MCS (make sure you check your supplier is signed up to the scheme), as this ensures the Air Source Heat Pump will be of suitable quality to fulfil your needs.

Offset cost of running Air Source Heat Pumps if possible

Air Source Heat Pumps require electricity to operate (unfortunately). But you can offset this to a degree by having Microgeneration technologies installed in your home, e.g. Solar Photovoltaic Cells, Micro Hydro Electric or Wind Turbines.

The Coefficient of Performance is a very important consideration

The Coefficient of Performance (CoP) is a measure of how efficient your heat pump is. For example if 1 unit of electrical energy is input into the Air Source Heat Pump, it should provide about 3.5 of useful heat energy (therefore it has a CoP of 3.5). The CoP varies between different Air Source Heat Pumps, so when buying a unit, remember the higher the CoP the better. The higher CoP Air Source Heat Pumps are usually more expensive (not always the case but check the manufacturer).

Air Source Heat Pumps perform poorly in low temperatures

Be aware that although Air Source Heat Pumps can still extract heat from the air in temperatures as low as -25⁰c, the amount of heat they will provide at these temperatures will be much lower than if you live where there is an higher ambient temperature. So if you live somewhere that has a very cold ambient temperature, potentially look at other self generation energy solutions. 

“Top-up” or secondary heating may need to be installed

The temperature of the water that an Air Source Heat Pump will produce is not as hot as a traditional boiler system, so you may need to consider secondary heating sources that act as a “top-up” heat form. Very popular is a log wood burning stove or an infrared heating panel.

Air Source Heat Pumps may irritate your neighbours

Air Source Heat Pumps produce noise, not a lot, but best to ensure it is not situated directly outside your bedroom or too close to the boundary of your next door neighbour. We filmed this short video clip on YouTube about Air Source Heat Pumps, therefore decide for yourself on the potential noise levels.

Always follow the latest planning guidelines prior to installation

In terms of planning permission, Air Source Heat Pumps are normally listed under permitted developments so no specific planning permission is actually required, however for this to be the case you do need to adhere to certain criteria of which the main one is related to neighbours and ensuring there is a suitable distance between your heat pump unit, and their house (please check with your installer / planning authority to make sure you adhere to building regulations).

Positioning of the system will drive its performance

You need to install your Air Source Heat Pump outside where there is a sufficient ambient air flow (we suggest doing so on ground level so it is easy to reach if it needs maintenance). Air Source Heat Pumps work by taking heat out of the air, so if you were to position it in an enclosed space, then it wouldn’t be effective.

Ensure you have a few quotes before you make a decision

As with all serious investments it is worth getting several quotes before investing in an Air Source Heat Pump. We also recommend speaking to other customers of your proposed installer, get their views and put your mind at rest when they tell you they have had a job installed to satisfactory standards.

If you are unsure about where to read up further about Air Source Heat Pumps because the whole thing sounds like a bit of a minefield, then we suggest going onto the MCS website and clicking on the section about manufacturers. It is worth speaking to a number of manufacturers so you get a feel for what the unique capabilities are of the systems you are looking to have installed in your property.

Our View – Heat Pumps

Heat pumps are the most efficient way to heat an off-gas grid property. They utilise some really clever physics to convert electricity to heat at very high efficiency (anywhere from 250 to 450%). There are 2 main types of heat pump – air source and ground source, with very different benefits and costs. The bottom line is that heat pumps can really work for some homes, whilst for others they will be an expensive waste of time, so make sure you read up and make the right decision!

What type of heat pump?

Air source heat pumps are more compact and suitable for smaller urban properties, but a ground source heat pump is more efficient and will pay you more via the RHI. You can read more about the differences in this article.

Insulation a key factor

Insulation is absolutely key for a heat pump. If your property is poorly insulated, the heat pump will not be able to sufficiently heat the property. Make sure you get you loft and cavity walls insulated to the latest building regulations, or if you have an older solid wall property that you have installed solid wall insulation. More information on insulation for heat pumps can be found here.

What is the cost of a heat pump?

An average air source heat pump will set you back anywhere from £5,000 to £10,000, whilst a ground source system will be closer to £25,000. If you need to add in a wet central heating system as well, you will need to tack another £5,000 on to the price, dependant on the size of the house of course. You can read more on costing a heat pump here.

What funding is available for heat pumps?

Unfortunately you can’t use the Green Deal to get some help towards the initial cost, the reason being that the initial outlay should be recovered through the Renewable Heat Incentive (RHI) subsidy. The RHI will pay you a regular income for the system over 7 years, in some cases paying back around half of the initial costs, which means that if you can afford it up front, a heat pump can really pay back for you.

Expected returns on your installation

This will depend on what you were using before hand, but combined with the RHI the payback should be within 7 years of the initial investment.

What is the best setup?

Your heat pump should be installed in the property along with excellent insulation and ensuring there are no draughts or cold spots. You should also consider underfloor heating for your ground floor as an option instead of radiators, because underfloor heating works at a lower temperature – ideal for heat pump efficiency.

Mr Chaggar from Ealing, London not only benefits from a well insulated home but he and his family can utilise renewable heating and electricity both produced on site. As the home is fairly new and has been insulated throughout, which means it requires less amount of energy to provide for the needs of the people residing there.

Mr Chagger used TheGreenAge’s partner Complete Plumbing Clean Energy (CPCE) to carry out the work on the heating and solar PV system. CPCE provide a high level of precision and engineering expertise to deliver projects of this type.

By combining electricity produced on site means that some of this energy is then used to power the compressor on the air source heat pump, there is little use for gas central in this instance.

The installation includes the following:

• Mitsubishi Ecodan air source heat pump
• Underfloor heating throughout the property
• 1kWp Bisol solar PV system
• High efficiency hot water tank

Grants and Subsidy benefits to the customer

• Renewable Heat Incentive (RHI) payments for producing renewable hot water on the air source heat pump;
• Feed-in Tariff payments for the electricity produced and exported by the solar PV system

While there is an upfront cost component to paying for the solar PV and the air source heat pump, because of the Government subsidies available, the cost should be recovered within the first 7-8 years on both systems. While there isn’t Green Deal Finance help on the air source heat pump (due to the RHI), customer can get help from this funding for a solar PV system.

To claim the RHI, and potentially get some funding from Green Deal Finance for solar PV, the customer has to have a Green Deal Assessment (carried out here by us, TheGreenAge) and have an MCS certificate produced by the installer (produced by CPCE).