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Installing Air Source Heat Pump

Air source heat pumps (ASHPs) are a popular renewable heating system, suitable for a wide range of homes and building projects. With the RHI (Renewable Heat Incentive) incentivising homeowners with grants, and an ongoing focus on more energy efficient ways to heat properties, now is a great time to embrace low-carbon heating technology.

Installing an air source heat pump is simple and doesn’t need extensive groundworks. Any plumbing or heating engineer is able to install an ASHP, with the help of our MCS (a standards organisation who certify renewable products) support packages. Nu-Heat can take on all the MCS compliance paperwork and can also commission the system for you.


Jump to a section below to find out more about ASHPs:

Air source heat pump

Are air source heat pumps worth the cost?

Installing an ASHP can reduce energy consumption for heating by 75%, compared to electric heating systems.

Air source heat pumps essentially offer ‘free’ energy. They deliver more heat energy than the electrical energy they take to operate. This can potentially save you money on bills, especially if you have no access to gas central heating.

As a comparison, if an electric fire uses 1 kWh of electricity, it delivers 1 kWh of heat, meaning its ‘Coefficient of Performance’, or CoP, is 1. This means that the electric fire heating system is 100% efficient.

However, if 1 kWh of electricity is put into an ASHP, it could deliver 3 kWh of heat, giving it a CoP of 3. The air source heat pump has extracted an extra 2 kWh of ‘free’ heat from the air for use in heating and domestic hot water.

Whether an ASHP is worth the installation cost depends on your type of home, and your existing heating system.

Want to talk to an expert about air source heat pump costs? Contact us to find out more.

Grants for air source heat pumps (The Domestic RHI)

The Government recognises that ASHPs have a part to play in making UK housing more energy-efficient and reducing energy bills. This is why they have been included in the RHI (Renewable Heat Incentive).

To help offset the cost of installing an ASHP, a homeowner can expect a tariff rate of 7.3p/kWh.

A typical home using around 20,000kWh per annum of heating requirement could get around £7,000 in payments over a seven year period – a considerable amount to go alongside the savings on energy bills. Visit Ofgem to find out more.

Installing Air Source Heat Pump

Air Source Heat Pump Installation – Is Your Home Suitable?


The most important consideration when checking the suitability of an air source heat pump for a project is how much insulation is present. A well-insulated property will prevent heat escaping, enabling the heat pump to work efficiently at lower flow temperatures, providing the homeowner with an effective, economic heating system.

The insulation present in all new build properties built to Part L1A, and generally those built in the last 10 years, are likely to be suitable for an air source heat pump. Older properties will require insulation upgrades such as loft, cavity wall and glazing improvements in line with Part L1B of the Building Regulations.

Access to mains gas

In an existing property, an ASHP is generally beneficial only if there is no access to mains gas. Homeowners will see a greater return on investment when compared to the cost of running their previous oil, LPG or electric heating system.

New build properties that have access to mains gas are still suitable for an air source heat pump, which will perform very efficiently. This option is often chosen when aiming to create an eco-home that is not reliant on fossil fuels.

Planning permission for heat pumps

Most air source heat pump installations will fall into the category of permitted development in line with MCS020, so will not require planning permission. Obviously, it is important to check this before getting started!

If the property is listed, in an AONB or Conservation Area, or requires more than one heat pump unit, planning permission will be required and the homeowner will have to apply for this.

Find out more about ASHPs and planning permission

The heat emitter – underfloor heating or radiators?

Air source heat pumps work most efficiently when connected to low temperature heat emitters, such as underfloor heating, or a combination of underfloor heating and radiators. 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.

Air source heat pumps

Installing an Air Source Heat Pump – 3 Key Stages

It’s important to remember that in order to qualify for the Domestic RHI, both the system and the installer has to be MCS approved. Nu-Heat offers support packages to both MCS and non-MCS installers – call 01404 549770 for more info.

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 solution will be efficient and work as expected. 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. This cuts down significantly on the amount of time an installer needs to spend on paperwork and is essential should the homeowner wish to apply for the Government’s RHI scheme (annual tax-free financial support payments)
  • Mechanical and electrical drawings specific to the installation as well as clear installation manuals and customer user guides

Step 2 – Installing an air source heat pump

Heat pump installation 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

On completion of the first and second fix installation of the mechanical and electrical heat pump components, the ASHP unit will be ready for commissioning. It’s this element of the install that can be seen as a little daunting for a first-time ASHP installer, which is why Nu-Heat offers various levels of support:

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

MCS paperwork. Whether MCS or non-MCS registered, an air source heat pump installer can choose a support package to pass over the cumbersome compliance paperwork to Nu-Heat, freeing up time to spend out on the job and not in the office. Nu-Heat also completes and provides all of the relevant MCS support documentation for the homeowner’s RHI application, warranties and guarantees

On commissioning, the installer will also receive a handover pack that is passed on to the homeowner. This includes everything required for MCS compliance, as well as air source heat pump user guides.


How do air source heat pumps work?

ASHPs work by using warmth extracted from the air. This low temperature warmth is absorbed by a fluid held in the ASHP, which passes through a compressor. Its temperature is then increased, before being made available for the heating and domestic hot water circuits of the property.

An air source heat pump can operate in temperatures as low as -20˚C. Find out more below.

Air source heat pumps and underfloor heating systems

An ASHP reaches its highest levels of efficiency when producing low flow temperatures. It’s the lower flow temperatures required by underfloor heating that make it the perfect partner for air source heat pumps.

By integrating the two systems together, both technologies play to their strength and maximum efficiency can be achieved without compromising comfort. Find out more about Nu-Heat underfloor heating here.

Coastal Installation – An ASHP & Blygold Case Study

Unlike ground source heat pumps, that require a plant room and either land for ground loops or the right conditions for boreholes, air source heat pumps require less space for installation.

However, in certain locations there may be considerations to ensure ASHPs continue to perform to their optimum levels – for example, air source heat pumps situated on the coast.

A ‘coastal’ installation refers to a property that is located within 4 kilometres of the sea ‒ and as Britain is an island, there are a large number of houses that fall into this category. When Nu-Heat specifies any heat pump, a coastal location will be flagged up by the estimators who consider the property’s location in order to size the unit – in accordance with MCS.

Properties on particularly exposed coastal locations, such as a cliff top facing out to sea, have a greater heat loss. An increased ‘exposure’ figure is included in the heat loss calculations. Advantages for air source heat pump systems situated on the coast is that the air temperature is generally warmer and there is less chance of frost.

The main disadvantage for a seaside air source heat pump is that the salt in sea air may corrode the heat exchanger within the heat pump. The solution to this is fairly straightforward. Every air source heat pump that Nu-Heat specifies for a coastal location is treated with Blygold anti-corrosive coating.

Blygold has traditionally been used to protect HVAC coils, and is ideal for air source heat pumps. The coating provides a long lasting corrosion protection without affecting heat transfer and pressure drop, protecting the surface from premature deterioration. The heat conductive pigmentation in the coating creates a very high chemical resistance at a low layer thickness. One coating should last for five years and can last longer, depending on actual location. The customer is asked to wash the coating annually with soapy water and inform Blygold that they have done this.

If the coating shows sign of wear, Blygold can supply a touch-up kit or there is an option of a refurbishment programme that will ensure performance and longevity, although this is unlikely to be required in most situations.

An air source heat pump should not be contained it in a tight space, next to a high fence or against the wall of the house. This is as air may leave the unit and return straight back on the other side, reducing efficiency.

With many remote locations having no access to natural gas, the installation of an air source heat pump is an ideal solution, as long as insulation levels are sufficient. Although all new builds will achieve these levels, older properties are likely to require improvements through various combinations of loft, door and wall insulation and double glazing.

Read more case studies for air source heat pumps.

Key benefits to air source heat pump installers

  • Reduction in the number of free call-outs you, the installer has to make
  • Reassurance for your customers that they will not incur unexpected charges
  • Reduction in the number of phone queries you will receive as Nu-Heat will provide free telephone support direct to your customers

I’m interested in installing a heat pump! What are the next steps?

  • Call our team on 01404 549770 to discuss your project requirements
  • Send us a copy of your project plans online, by email or in the post for a free bespoke quote
  • Sign up to our mailing list to receive advice for your project, product news and free tickets to meet our underfloor heating and renewables experts at shows in your area

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