Is An Air-To-Air Heat Pump Suitable for Your Property?

The UK government announced during last month’s budget that it was expanding its Boiler Upgrade Scheme (BUS) to include air-to-air heat pumps. It is offering a £2,500 grant for their installation in addition to its current £7,500 discount on air-source or ground-source heat pumps for homes. This is the first time that air-to-air heat pumps, a technology which provides heat in the winter and keeps houses cool during the summer, have been eligible for government support.

The change is aiming to help more people, especially those living in flats or smaller homes, upgrade to lower-carbon heating and cooling options. These grants will be available for all households, forming part of the Government’s £13.2bn Warm Homes Plan, which was created to bring down bills for around five million homes.

This extension of the Boiler Upgrade Scheme comes after a record-breaking year for domestic heat pump installations, with September seeing the most applications on record.

Separate to the government’s new initiative, the UK’s MCS certification scheme is consulting on a new standard to include air-to-air heat pumps and in May this year a regulatory change in the UK removed planning restrictions that previously limited their installation in certain areas. 

Government Ministers are looking at ways of ensuring that all households have access to low-carbon heating options. They are currently consulting on alternative heating systems, for example storage heaters, infrared panels and renewable liquid fuels, and the role they can play in keeping our homes warm.

Minister for Energy Consumers Martin McCluskey said: 

“With heat pumps more popular than ever, we want to make sure as many people as possible can benefit, especially those in flats or small homes without central heating, so they have greater choice when upgrading their property. We are also offering discounts for heat batteries and consulting on the role innovative, clean heating solutions can play, including thermal storage, infrared panels, and renewable fuels.”

Are Air-to-Air heat Pumps already popular in the UK?

The two most common types of heat pump are air-to-air and air-to-water heat pumps each with distinct benefits and drawbacks. A significant portion of the 320,000 or so heat pumps installed in the UK are air-to-air heat pumps. However, this type of heat pump cannot be used to heat your hot water which has limited their residential popularity. Most households need to use an alternative water heating system such as an existing boiler, electric immersion heater, or heat pump hot water cylinder. This can end up making the switch to the air-to-air heat pump costly.

There are some systems that can integrate a hot water supply though these are generally suited to small homes or self-contained spaces like loft conversions. Air-to-air heat pumps tend to be more popular in the commercial sector, as they can provide companies with an affordable way to keep their buildings warm. Office buildings are usually much bigger than residential homes so they can use units that are far larger and more powerful whereas residential heat pump units can only ever be so big. 

This article’s main focus is to check whether an air-to-air heat pump is the best solution for your property.

How Do Air-to-Air Heat Pumps Work?

In a nutshell, air-to-air heat pumps operate by extracting heat from the external air and transferring it into your home via a series of indoor air units. In warmer months, they can also function as air conditioners, removing heat from inside the house and releasing it outdoors. In fact, these kinds of heat pump look a lot like traditional air conditioners. They work in a similar way to a fridge, but in reverse when heating. The system consists of an external unit connected to indoor fans via refrigerant-filled pipes.

A2A heat pumps come in two main configurations:

• Single-unit systems: One outdoor unit connected to one indoor fan.
• Multi-split systems: One outdoor unit connected to multiple indoor fans (up to five).

In addition to heating and cooling, A2A systems offer air filtration and dehumidification, enhancing indoor air quality.

Here are the basic steps in their operation:

• Absorbs heat from outside air – The outdoor unit contains refrigerant fluid that can absorb heat from the air even in cold weather.
• Compresses the refrigerant – The refrigerant, now a gas, is compressed, which raises its temperature rather like a bicycle pump which gets hot when you inflate a tyre.
• Transfers the heat indoors – The hot gas flows to the indoor unit, where air from your room is blown over the coils, warming it.
• Condenses and recycles – As the refrigerant gives up its heat, it condenses back into a liquid and cycles back to the outdoor unit to repeat the process.
• Reverses cycle for cooling – In summer, the system works backwards, moving heat from inside your home to the outdoors.

Pros and Cons of Air-to-Air Heat Pumps

Pros:

• They provide dual functionality, both heating and cooling which makes them ideal for use throughout the year.
• They are highly efficient and sustainable with a Seasonal Coefficient of Performance of up to 6. A SCOP of 6 means that for every 1-kilowatt hour of electricity used the system produces an average of 6 kilowatts of heat. They can often reduce heating costs when compared to conventional electric or gas systems as well as significantly reduce carbon emissions and reliance on fossil fuels. 
• They offer quick and effective heating as they warm up rooms quickly and distribute heat evenly through air circulation. This also makes them ideal for open-plan spaces. 
• They are easier to install than air-to-water systems as they do not require water pipes and radiators.
• They are typically cheaper to install than air-to-water heat pumps. 
• They can work alongside existing boilers.
• They require little maintenance.

Cons:

• Unlike air-to-water heat pump systems, air-to-air heat pumps do not provide domestic hot water.
• They may require ducting or multiple indoor units which can make installation costs more expensive.
• They are less effective in extremely freezing weather. Although they are efficient in moderate climates their performance can decline in exceptionally low temperatures.
• They are not as efficient for the larger home. 
• The indoor units can be noisy. 
• They may require multiple indoor units, which can impact aesthetics.
• There are a limited number of qualified installers for domestic installations. 

Key differences between Air-to-Air and Air-to-Water heat pumps.

• Heating and cooling capability:

Air-to-air heat pumps are great for homes that need both heating and cooling, while air-to-water systems are more focused on heating and domestic hot water. If cooling is important, an air-to-air heat pump is the better choice.

• Energy Efficiency and Costs:

Although both systems are energy-efficient, air-to-water heat pumps tend to provide greater long-term savings due to their ability to heat water for both space heating and domestic use. However, in milder climates where less heating is needed, air-to-air heat pumps may have lower operational costs. 

• Installation and Maintenance:

Air-to-air heat pumps usually have a lower upfront cost and are easier to install, especially in homes without existing wet heating systems. By contrast, air-to-water systems need to be integrated with radiators or underfloor heating, which increases the complexity of the installation and overall cost. 

• Space and Aesthetics:

Air-to-water heat pumps need a hot water cylinder and additional plumbing which means that they are not ideal for the smaller home. Air-to-air heat pumps are easier to install but may require more indoor units which can be less aesthetically pleasing.

Is an Air-to-Air Heat Pump Right for You?

If you live in a small home or apartment where space is limited, or if you have an open-plan layout or no wet central heating, an air-to-air heat pump is likely to be especially well-suited to your needs. Unlike the air-to-water heat pump, it doesn’t require extra space for water storage. You may find the air-to-air heat pump an attractive alternative to your traditional gas heating system as it offers high efficiency and dual functionality, the option of heating or cooling. However, just as with air source heat pumps the systems’ effectiveness relies heavily on good insulation.

Your installation costs may well be lower than for an air-to-water heat pump especially if your property is small. If you are thinking of installing a simple air-to-air heat pump you can expect to pay an average cost of £4,500. In the past there were no government incentives to help with the initial outlay for air-to-air heat pumps and the Boiler Upgrade Scheme only covered air-to-water heat pumps, ground Source heat pumps, and biomass boilers. That has now changed and you can apply for £2,500 towards the cost of your air-to-air heat pump as well as £2,500 towards the cost of a heat battery which can store your heat overnight for use during the day.

Before you buy an air-to-air heat pump it is crucial to have a professional assessment to ensure efficiency and cost-effectiveness. The installer will check the sizing for your home’s heat loss and design the right system for you.