FAQs - Air source heat pumps

Following the increase of the energy price cap, air source heat pumps are now part of the mainstream conversation when it comes to energy efficiency and saving money on energy bills.

We’ve pulled together a list of FAQS dealing with cost, efficiency, how air source heat pumps work and the financial incentives available to those thinking of installing one at their home.

What is an air source heat pump and how do they work?

Air source heat pumps are a renewable energy technology designed to replace traditional heating systems. They look like air conditioning units and are positioned outside of the property.

They operate like a refrigerator, but in reverse. Heat from the air is absorbed at low temperature into a fluid. This fluid passes through a compressor, increasing the temperature, which is then used to heat water for use in your home.

Air source heat pumps require electricity to operate but as they extract natural heat from the air, they have lower running costs and environmental impact than electric, oil and solid fuel heating systems. This makes them particularly suitable for off gas properties.

During winter, your air source heat pump may need to be on constantly to heat your home efficiently. You will notice that radiators will not feel as hot to the touch as they might do when using a gas or oil boiler, but your home will feel warm and comfortable all winter. A heat pump will continue to generate heat from the outside air even when the temperature is as low as -15C.

Unlike gas and oil boilers, heat pumps deliver heat at lower temperatures over much longer periods. You may have to install larger radiators to make the most of the central heating system, however your contractor will advise you fully on this.

Why should I consider installing an air source heat pump?

There are both financial and environmental advantages to installing an air source heat pump in your home.

Air source heat pumps provide more efficient heating than oil or electric heating systems, resulting in lower carbon emissions. For every unit of electricity consumed by an air source heat pump, three units of heat are produced.

Air source heat pumps provide the biggest benefit to well insulated, off gas properties. Reduced energy bills can be expected, especially if you are replacing conventional electric heating. Running costs can potentially be higher when compared to new, efficient gas boilers. However, savings are still possible if replacing older and more inefficient gas boilers.

Do air source heat pumps use a lot of electricity? How expensive are they to run?

Typically heat pumps use less energy than a traditional heating system such as electric storage heaters. For example, if you buy one unit of electricity this will be turned into one unit of heat energy by a storage heater.

With an air source heat pump, for every unit of electricity used will produce approximately three units of heat energy in return, making it three times more efficient than storage heating.

Do I have to pay a contribution towards the cost of installing the heat pump? What help is available to cover the cost?

The initial cost of a heat pump will generally cost more than a new boiler, but there is financial support available via a £10,000 Home Energy Scotland Loan (£2,500 loan plus £7,500 cashback) to install a ground or air sourced heat pump at your home. The biggest benefit of course will be more energy efficient home and significant reduction in your energy bills.

If you rent your property privately the decision to take part in the project lies with your landlord. The level of funding available to private landlords is dependent on their personal circumstances.

If you rent your property through the local authority or housing association you will not need to pay anything towards the installation or maintenance of the heat pump, you will just pay your energy bills as usual.

What is the installation process? Will there be any disruption? How long will it take?

Once you have decided to proceed with installing a air source heat pump you will enter a contract with a contractor for the works to be carried out to your home. The works will be scheduled, and notification provided in writing. If you rent your home from a Local Authority or a Housing Association, your home may automatically be included, this will be confirmed by your landlord.

The contractor will discuss with you the installation process including the positioning of the air source heat pump and the level of disruption to expect. Installation will usually take up to five days to complete, depending on your current heating system. You may have to carry out some minor preparation for the install such as moving personal belongings. The contractor will be able to advise you fully following the technical survey of your property.

Installation is likely to require access to all rooms in the property and does involve activity as drilling, so there will be some noise and disruption. Pets may find the noise distressing, so please be aware, and always keep them supervised.

Are my existing radiators likely to be suitable for the new system?

Air source heat pumps operate at lower temperatures than alternative ‘wet’ central heating systems. For this reason, they require distribution systems with a larger area such as under floor heating or larger radiators.

If you have radiators already it is likely these will need to be replaced with larger models.

Will I need a building warrant?

No, installing a heat pump does not require a building warrant.

What is the lifespan of the air source heat pump? What maintenance is required out and who do I talk to if I have a fault?

With regular scheduled maintenance you can expect an air source heat pump to operate for 20 years or more.

Air source heat pumps require maintenance like any other central heating system to ensure it remains safe and operates efficiently. Some maintenance is straight forward and can be carried out by the householder, but other maintenance should be done by a professional.

Typical maintenance includes:

  • A yearly check that the air inlet grill and evaporator are free of leaves or other debris.
  • Detailed check by a professional installer every year.
  • Removal of any plants that have started to grow around the heat pump.
  • Check the central heating pressure gauge in your house from time to time. You will be shown how to do this by the contractor.
  • Use anti-freeze in colder weather to prevent the heat pump from freezing. Levels of anti-freeze and its concentration vary but this will be explained to you by the contractor.

Your heat pump will also be covered via warranty, details of which will be provided by the contractor.

Is an air source heat pump noisy?

A small amount of noise is produced from the fan within an air source heat pump while it is in operation. The noise is minimal though and should not be disruptive. The air source heat pumps fitted in this project have been specifically designed for UK residential use with sound pressure levels of around 45dB(A). For comparison, a typical library has a sound pressure level of 40dB(A) and a room conversation comes in at around 60 dB(A).

What if there is a power cut, will my heating be affected?

An air source heat pump requires electricity to operate so a power cut would result in a temporary loss of heating and hot water. This would happen with any heating systems which use electricity to generate heat and even some systems like gas and oil which require electricity to spark combustion.

Unless you live in an area which is prone to regular disruption of electrical supply this is not likely to be an issue.

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