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Air to Water Heat Pumps vs Air to Air: Which is Best?

Nick Geary
By: Nick Geary
Updated: 9th March 2022

water vs air
There are 2 different ways an air source heat pump can provide heat in your home: by heating the air in the rooms or by heating the water in the central heating system, but which option is best for your home? We've compared these different heat pumps, to help you find out.

Air to water heat pumps

As the name suggests, air to water heat pumps use the ambient air outside of a property to heat the water in the central heating system. They are the more frequently seen air source heat pumps on the market, and come with a number of benefits and disadvantages.

Benefits of an air to water heat pump

Air to water heat pumps come with several benefits when compared to air to air heat pumps.

Compatible with traditional central heating systems

According to the English Housing Survey 2019-2020, 90% of households in the UK have central heating with radiators as their main heat source. That means, unless you're among the select few, you are going to want an air source heat pump that's compatible with your existing central heating system. Air to water heat pumps are designed with this very purpose in mind. Air to air heat pumps are not compatible.

Easier to install

As air to water heat pumps will generally connect directly to the central heating system they are usually a lot easier to install than air to air heat pumps. Installing an air to water heat pump in a property with existing central heating is similar to replacing a boiler, whereas installing an air to air heat pump would require the installation of air ducts throughout the property.

Not just for heating

Although air source heat pumps are mainly considered for heating properties, that isn't the only thing they do. Air to water heat pumps will heat up the water in your property for your central heating, but can also be combined with a hot water storage tank to provide hot running water too.

Disadvantages of an air to water heat pump

Air to water heat pumps don't just come with benefits, there are some disadvantages too.

More expensive

Air to water heat pumps are not cheap. Depending on the size of the unit you need and which manufacturer you pick, you could end up paying more than £10,000 for an air to water heat pump, excluding the cost of installation.
In comparison, you can get some air to air heat pumps for less than £1,000. Even if the cost of installation is high, you could still spend less on getting an air to air heat pump installed than you would on just buying the parts for an air to water heat pump.

Requires more space

In addition to the space a hot water storage tank would take up to allow for hot running water, due to radiators being required, air to water heat pumps still take up more room in a property than air to air heat pumps do. This isn't much of a problem if you already have radiators installed, but to maximise space in a new property air to air heat pumps are the better option.

Air to air heat pumps

In what sounds like a much simpler process, air to air heat pumps extract heat from the ambient air outside of a property and transfer it to the air inside of a property. If you'd like more detail on how air source heat pumps actually work, have a look at the following article: What is an air source heat pump?

Benefits of an air to air heat pump

There are several benefits to having an air to air heat pump rather than an air to water heat pump.

Heat and cool

As air to air heat pumps are essentially air conditioning units that are capable of heating a property, they can also be used to cool a property when the weather is hot. Many manufacturers refer to them as climate control solutions because they aren't just for heating a property, they can cool it too.

Save space

Air to air heat pumps may require the installation of air ducts throughout the property, but once they have been installed, each room will feel more spacious. This is because there is no need for radiators which take up wall room and floor space. For newer, less spacious properties, air to air heat pumps could definitely help you make the most of your space.

Less expensive

As mentioned earlier, air to air heat pump units are considerably cheaper than their air to water counterparts. Some air to water units can be 10 times more expensive than an air to air unit, which is something to think about.

Disadvantages of an air to air heat pump

Air to air heat pumps don't just come with benefits when compared to air to water heat pumps, there are some disadvantages too.

Not compatible with traditional central heating systems

If you have an existing central heating system and want to replace a gas boiler with an air source heat pump, air to air heat pumps are not for you. As they only heat the air in a property, they cannot be connected to the central heating system and are completely incompatible.

Higher installation costs

Although like-for-like installation costs for both types of heat pump are generally quite similar, unless you have a property with existing air conditioning ducting, the cost of installing an air to air heat pump is likely to be higher as there will be more work to do.

No hot water

Air to air heat pumps do not heat the water in a property. This means you will need a secondary source of heat to provide hot running water throughout your home. While this is possible through solar power and other water heating solutions, it is still a separate cost that is avoided when installing an air to water heat pump.

Which heat pump is best?

Having learned the advantages and disadvantages of these air source heat pumps, you should now be able to make a decision on which would be best suited to your circumstances. However, as there is a lot to consider when getting an air source heat pump installed, we would recommend seeking the advice of a local heating engineer. They can ensure you get the right solution for your home's unique circumstances. Fortunately, we can help you find qualified engineers in your area, who will provide you with free, no obligation quotes. All you need to do is click the link below.



Nick Geary

About the author

Nick Geary

Nick has a wide range of experience writing about conventional and renewable heating solutions, and is always increasing his knowledge by researching any new heating technologies on the horizon.

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