Air source heat pumps
What is an ASHP and how do they work? Here’s how our quiet, efficient air source heating systems can save you energy and money.

ASHPs are a popular low-carbon, renewable heating system. They are suitable for a wide range of properties and are also eligible for the Renewable Heat Incentive scheme.
What is an ASHP system?
An ASHP is a low-carbon, renewable heat source that is suitable for a wide range of homes.
They extract heat energy heat from the air in order to heat your home. Aside from their eco-credentials, an ASHP system is also very efficient.
For every unit of energy it uses to extract heat from the air, it typically outputs three times more as heat, meaning ASHP efficiency is around 300%!

The benefits of ASHPs
- Low carbon, environmentally-friendly heat source
- Highly efficient, transferring around three times more energy into a home as heat than it uses to extract it from the air
- MCS approved for the Renewable Heat Incentive (RHI)
- Little outdoor space required, meaning an ASHP system is suitable for most urban properties

How does an ASHP work?
An ASHP collects energy from the air, even at low temperatures.
The energy is absorbed from the air to the refrigerant in the evaporator.
This process increases the temperature of the refrigerant, changing it from a liquid to a vapour.
The vapour is compressed by an electrically driven compressor, increasing its temperature.
The condenser releases this heat energy into the water used in your heating and hot water system.
The cooled refrigerant turns back into a liquid and the process starts again.
A little extra – in this video you’ll discover
How does an ASHP work?
Would my property benefit would benefit from an ASHP
Do I need planning permission to install an ASHP?

Nu-Heat’s ASHP range
At Nu-Heat, we only use the highest quality, tried-and-tested components for all our systems. That’s why we design and supply NIBE ASHPs as an efficient, low-carbon, solution for domestic hot water and space heating.
NIBE ASHPs
Swedish company, NIBE, has been manufacturing heat pumps globally for 40 years.
Their industry-leading ASHPs not only look great, they also offer the highest levels of performance and functionality.
- Incredibly quiet thanks to Owl Wing fan design, producing maximum sound power levels as low as 50 decibels
- Intuitive control with smart connectivity
- Compact units available from 6kW up to 16kW
- Cascade and hybrid options to suit a wide range of properties
- MCS approved for Renewable Heat Incentive applications
- 7-year warranty when commissioned by a Nu-Heat engineer

NIBE Model | 6kW | 8kW | 12kW | 16kW |
CoP at 7/35 °C* | 3.5 | 4.3 | 4.5 | 4.53 |
Operating voltage | 230V 50Hz | |||
Weight (kg) | 66 | 90 | 105 | 135 |
Dimensions (height includes stand) | H791 x W993 x D364 mm | H945 x W1035 x D422 mm | H1045 x W1145 x D452 mm | H1500 x W1145 x D452 mm |
Max sound power level (dB(A))** | 50 | 54 | 57 | 61 |
Panasonic ASHPs
Another highly efficient option is the Panasonic ASHP range. Available as single units from just 5kW, they offer a lower initial investment for homeowners looking to make the switch to renewable, low-carbon heating.
- 5kW – 16kW models available
- Maximum sound power levels as low as 59 decibels
- Simple, compact controller
- Built-in filter and charge pump
- MCS approved for Renewable Heat Incentive applications
- 7-year warranty when commissioned by a Nu-Heat engineer

Panasonic model | 5kW | 7kw | 9kw | 12kw | 16kw |
CoP at 7/35 °C* | 5.08 | 4.76 | 4.48 | 4.74 | 4.28 |
Operating voltage | 230V | ||||
Weight (kg) | 99 | 104 | 140 | ||
Dimensions (height includes stand) | H865 x W1283 x D320 mm | H1410 x W1283 x D320 mm | |||
Max sound power level (dB(A))** | 59 | 69 | 72 |
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How are ASHPs installed?
Installing an ASHP is simple. There’s no need for extensive groundworks and any plumber or heating engineer can install an ASHP with our support. Nu-Heat can even take on all of the MCS paperwork and commissioning for the system, ensuring the heat pump is installed correctly and meets the criteria required for the Green Homes Grant and the Renewable Heat Incentive.
There are 3 key stages to installing an ASHP:
Step 1 – Finding the right heat pump supplier and design
Choosing an experienced ASHP supplier is essential when it comes to heat pump system design. You need to be confident that the system will be efficient and work as expected, keeping running costs low. Nu-Heat offers the following as standard:
- Advice and guidance on the suitability of an ASHP for the project
- Full heat loss calculations for the property in order to correctly size the ASHP
- An accurate quotation for the system components in line with MCS and RECC standards
- Support with MCS compliance, including on-site commissioning
- Mechanical and electrical drawings specific to the installation as well as clear installation manuals and customer user guides

Step 2 – Installing an ASHP
Installing an ASHP is relatively simple for any plumbing and heating engineer. The heat pump controls and pipework layout are very similar to a traditional gas or oil boiler, configured as a Y or S plan industry standard layout.
- The ASHP is placed on a flat concrete base external to the property with the appropriately sized flow and return heating pipes and electrical power cable running from the unit into the property
- Electrical work should be carried out by a qualified electrician in the conventional way as you would for a gas or oil boiler
To simplify the process, Nu-Heat provides a complete set of ‘as installed’ mechanical and electrical drawings, which will provide a fault-free template of the complete air source heating system layout.

Step 3 – Getting the heating system up and running
Once the installation of the mechanical and electrical heat pump components is completed, the ASHP unit will be ready for commissioning. As an MCS accredited company, we can help with this final step by providing:
- The MCS paperwork – Pass over the cumbersome compliance paperwork to Nu-Heat, freeing up time to spend on the ASHP installation. Nu-Heat also completes and provides all of the relevant MCS support documentation for the homeowner’s RHI application, warranties and guarantees.
- Onsite commissioning – To ensure the system is MCS compliant, Nu-Heat can send out one of our own field service engineers to commission and explain the system set up and functionality of the heat pump controls. We can also support with the handover to the homeowner.

It’s definitely a far cheaper and greener option than oil – and we will receive around £1,000 back from the RHI each year. Nu-Heat were brilliant from the start; so professional and helpful.
Frieda Garrett – Homeowner

The heat emitter – underfloor heating or radiators?
ASHPs work most efficiently when producing low flow temperatures. It’s the lower flow temperatures required by underfloor heating that make it the perfect partner for ASHPs.
By integrating the two systems together, both technologies play to their strength and maximum efficiency can be achieved without compromising comfort.
If traditional radiators are the preferred option, it’s worth bearing in mind that they will need to be sized in line with the lower water flow temperatures associated with heat pumps; this means they are generally twice the size of those used with a gas or oil boiler.

Is an ASHP system right for me?
An ASHP can be installed in a range of properties, whether small or large, rural or urban.
An ASHP is right for you if:
- You are looking for a low-carbon, eco-friendly and sustainable way to heat your home
- The property is well insulated – this is important for efficiency and keeping running costs low
- There is not enough outside space needed for a ground source heat pump – typically three times the total floor area of the property. For an ASHP, all you need is room for the unit to be fitted to an exterior wall, with enough space around it to get a good flow of air.
- You are installing, or already have, an underfloor heating system. ASHPs work particularly well with underfloor heating due to their low operating temperatures.

ASHP maintenance
Like most heat sources, an ASHP should be serviced each year by a competent heating engineer.
The service will include mostly visual checks, checking settings haven’t changed and that the heat pump is still working efficiently.
Maintaining your ASHP annually is also a requirement for the RHI tariff payments.

How much does an ASHP cost?
A high-quality and well-designed ASHP system costs start from £5,000. This includes:
- A bespoke design, tailored to the property
- Installation schematics
- Lifetime technical support
- MCS support to successfully apply for the RHI
- The ASHP, domestic hot water cylinder, buffer tank, circulation pumps and all of the connecting brassware for the components
It’s possible to offset the initial cost of installing an air source heating system by applying for government incentives like the Renewable Heat Incentive and Green Homes Grant.

RHI Payments | ASHP |
RHI Tariff payment pence / kWh | 10.85p |
Potential RHI payments over 7 years using an ASHP* | £7,000 |
*An average three-bed house using 15,000kWh of heating per year with a SPF of 2.7 for the ASHP. February 2020.
The cost to have an ASHP installed varies, but as a rough estimate, it is usually around half of the cost of the unit itself. Looking for an installer? We can help through Nu-Heat’s Registered Installer Network.
ASHP running costs
Off the gas grid? An ASHP is also one of the most cost-effective ways to heat your home. Take a look at this running cost comparison:
ENERGY SOURCE | INPUT COST | EFFICIENCY | OUTPUT COST |
---|---|---|---|
ASHP | 15.0p/kWh | 300% efficient | 5.0p/kWh |
Mains Gas | 4.3p/kWh | 89% efficient | 4.8p/kWh |
Oil | 4.9p/kWh | 91.6% efficient | 5.3p/kWh |
LPG | 5.8p/kWh | 89% efficient | 6.6p/kWh |
Electric | 15.0p/kWh | 100% efficient | 15.0p/kWh |
Logs | 8.3p/kWh | 80% efficient | 10.4p/kWh |
Coal | 6.3p/kWh | 80% efficient | 7.9p/kWh |
Wood Pellet | 5.5p/kWh | 90% efficient | 6.1p/kWh |
*Please use this table as a guide as energy prices can vary.
The Renewable Heat Incentive
The Government recognises that ASHPs play an important role in reducing carbon emissions from the UK’s homes. This is why ASHP grants have been included in the Renewable Heat Incentive (RHI).
To help offset the cost of installation, the RHI ASHP grant is set at a tariff rate of 7.3p/kWh. The exact ASHP grant amount over seven years depends on how much energy the household uses.
A typical home using around 20,000kWh per annum of heating requirement could receive around £7000 in payments over a seven-year period – a considerable sum to go alongside the savings on energy bills. Visit Ofgem to find out more about ASHP grants.

The Green Homes Grant
The government has also introduced a new grant that can be claimed from the end of September 2020 until March 2021. The Green Homes Grant offers vouchers to help reduce the upfront cost of low carbon and energy efficient home improvements.
There are a number of home improvements for which vouchers can be used, including the installation of ASHPs, ground source heat pumps and solar thermal.
The Green Homes Grant and the RHI scheme can be used together, with the voucher value being deducted from the RHI payments.

Air Source Heating FAQs
Is my property suitable for an ASHP?
Providing the property is well-insulated, an ASHP is likely to be suitable. Insulation is really important because it prevents heat escaping, enabling the heat pump to work efficiently at lower flow temperatures.
The levels of insulation in new build properties, and generally those built in the last 10 years, are likely to be suitable for an ASHP. Older properties will require insulation upgrades like loft, cavity wall and glazing improvements.
Can air source heating be installed in an older building?
Yes, it can, providing that the insulation is being improved – ideally as close to current build regulations as possible. This enables the ASHP to work efficiently and keeps running costs low.
How efficient are ASHPs?
An ASHP is around 300% efficient. This is because for every unit of energy it uses to extract heat from the air, it typically outputs over 3 units of heat energy into the property.
What are the incentives of buying an ASHP?
An ASHP is a low-carbon, efficient renewable technology. A big benefit is that it offers a cleaner and greener way to heat a home – no fossil fuels.
Aside from their eco credentials, an ASHP is also inexpensive to run and cost-effective in most projects, especially when you factor in the potential payback through the Renewable Heat Incentive.
Do I need planning permission to install an ASHP?
In the majority of cases an ASHP does not require planning permission, falling under Permitted Development in line with MCS020. Obviously, it is important to check this before getting started!
If the property is listed, in an Area of Outstanding Natural Beauty or Conservation Area, planning permission will be required.
How much space do I need for an ASHP?
Not much! The ASHP unit is fitted outside of the property. You will need some space inside for the domestic hot water cylinder, buffer tank and the other components.
For heat pumps up to 12kW, you need a footprint around the same size as a standard hot water cylinder – similar to a large airing cupboard.
How far away does the heat pump need to be from my neighbour’s house?
The actual distance a heat pump needs to be from a neighbouring property depends on the unit used and any fences, hedges, walls etc. between the heat pump’s location and the assessment position. This is covered by MCS020 – something we take care of for you.
Can any plumber install an ASHP?
Yes. Any competent plumber can install an ASHP to MCS standards with our support.
How can I ensure it is installed correctly?
Nu-Heat offers a unique ASHP MCS support package. This includes an on-site commissioning visit from one of our engineers who will check that the ASHP has been installed correctly.
How long does it take to install?
Plumbing an ASHP takes a similar amount of time to installing a conventional boiler. Electrically, heat pumps are a little more involved, so it may take a couple more hours to wire than a boiler.
Are ASHPs noisy?
No. An ASHP makes less noise than the flue of a gas boiler. NIBE ASHPs are the quietest on the market thanks to their Owl Wing Technology.
What are the maintenance processes and costs?
An ASHP should be serviced yearly to maintain the warranty and to ensure the system is working as it should be. Servicing is also a requirement under the Renewable Heat Incentive. It costs around £200-£300 for an annual service.
What is the lifespan of an ASHP?
NIBE ASHPs come with a 7-year warranty when commissioned by a Nu-Heat engineer but you can expect a life expectancy well in excess of 10 years.
Will an ASHP work with my existing radiators?
No, we would not recommend it. ASHPs are at their most efficient when producing low flow temperatures. Because of this, they should be paired with low temperature heat emitters, like warm water underfloor heating.
This stops the heat pump from overworking and keeps running costs low. Radiators are still an option but they would need to be oversized to effectively heat the room/s with lower water temperatures.
Can you program an air source hear pump to provide heating at certain times?
Yes, you can, but we would advise against it. This is because an ASHP is designed to work as a weather compensation system, running as and when needed to heat the home, rather than at predefined times.
Is an ASHP just an off-grid option?
No. Well-insulated properties that have access to mains gas are still suitable for an ASHP. Providing it is designed and installed correctly, the running costs will be low – comparable to mains gas – but with the added bonus of lower carbon emissions and quarterly RHI payments.
You will find that ASHPs are generally more popular in off-grid areas, and this is because they offer far lower running costs in comparison to oil, LPG or electric-only heating systems.
Want help finding the right renewables solution?
We would love to speak with you to discuss your project. If you have a question about your existing Nu-Heat system, our technical support team are at hand.