Air Source Heat Pumps – Benefits and Comparison

How do Air Source Heat Pumps perform in UK homes?

Air is all around us, so it makes sense to utilise it for heating. Ten years ago, an air source heat pump was relatively unheard of in the domestic world, but times have changed, and they are all the rage.

The question is – how do Air Source Heat Pumps perform in UK homes?

One of the greatest benefits of air source technology is the fact zero carbon is produced when in use but installing an air source heat pump can be complex and time-consuming.

An electrical heating installation is a very simple process, but the same cannot always be said for an air source heat pump. You must consider the pipe run from the external pump to the unit within the home, the electrical connections for both the pump and the water tank, the electrical demand on your property, the water storage tank that must be installed inside the home, as well as the noisy and rather large fan in your garden.

Air source heat pump

How do air source heat pumps work?

An air source heat pump works on the premise of taking in air, extracting the heat, sending that heat into a refrigerant, and generating more warmth through compressing said refrigerant.

The air is inducted through an external fan, which sits outside of your home. The external fan unit is usually rather large, which may cause issues when it comes to choosing a position for its installation. This is an excellent way to generate heat, but often doesn’t produce enough warmth for a radiator system.

How do heat pumps work

Do air source heat pumps provide enough heat?

In the winter months, the UK gets very cold, with temperatures often dropping below zero. Inducting air at a cooler temperature will force the supplementary element to kick in to boost the temperature, as the air is too cold at the point of induction, significantly reducing the benefit of an air source heat pump altogether.

Even with the element kicking in, the maximum temperature output for a heating loop from an air source heat pump is around 65 degrees. From a boiler, the water temperature for a heating loop would be over 80 degrees. Even the warmest of people would notice a significant difference in temperature between an air source heat pump and a boiler. This forces people to either install different radiators altogether, or radiators which are twice the size of the existing ones.

To combat this issue, many people oversize their radiators to deliver more heat into the property, which isn’t always possible due to space restrictions. Alternatively, people choose to run the air source heat pump alongside a secondary form of heat, again negating the benefits of an air source heat pump.

The other point to bear in mind is that with an air source heat pump, your heating and hot water are on the same system, therefore meaning if your heat pump fails, you are without both heating and hot water. In addition, heat pumps have been designed with a focus on domestic heating, rather than domestic water heating. By separating your heating and hot water, you can invest in a more efficient hot water system that has been designed specifically to heat water.

With the kW requirement of an air source heat pump often more than 10kW, having enough spare electrical load in a domestic property is often difficult, further adding to your woes.

Sustainable world using renewable energy

Is my home suitable for an air source heat pump?

A good level of insulation is also vital to retain as much heat as possible. Most UK homes are not airtight enough to use air source heat pumps for heating. Heating is all sized based on watts per square metre, but for an air source heat pump to function, your property must require a very low number of watts per square metre, something which is only achieved through high levels of home insulation.

For newer properties, this may not be as much of an issue, but if your property is older, you might struggle to retrospectively insulate it.

A recent report by the Energy and Utilities Alliance (EUA) also states that a, “majority of UK homes are not suitable for a heat pump.”

What are the alternatives to air source heat pumps?

The UK government are focusing on a renewable future and putting a lot of time and effort in to pushing air source heat pumps as the future, however heating is not, and has never been, one size fits all.

Let’s assume that the COP (which stands for coefficient of performance) of a Fischer heater is 2.5:1 and for an air source heat pump is around the same, is that the main point of contention?

In fact, no. Suitability is the matter at hand; the one thing that we all must ensure before making any decision. We as humans always look for suitability first and efficiency second. We purchase products that fit with our desired level of comfort, affordability and those that work around our lifestyle.

Fischer heater in the living room

For example, you would not buy a small car if you have a large family, just because that car is efficient. Instead, you would first look for a car that is large enough for your family, and then focus on efficiency afterwards.

At Fischer, we know through years of experience that there is no such thing as one size fits all. Every property is different, and every customer is different, thus the ideal solution is different in every situation. We also know that suitability counts for more, as that is what delivers our desired level of comfort.

Nobody would switch to a system that is worse than the one they currently have just because of its efficiency. Anybody who decides to do so would live to regret their decision.

There is no suitability test conducted on air source heat pumps. Any test is purely based on efficiency. With over 20 years’ experience of installing electrical heating systems in domestic UK properties, we know what UK homes and consumers need, and we know it isn’t one size fits all, hence why we offer a wide range of products to match every customer’s suitability.

However, the one aspect of suitability that we can agree on is that any heating system must have zero emissions.

Are air source heat pumps suitable for hot water?

Air source technology is not by any means redundant, especially when it comes to heating your water. Hot water is something we require 365 days a year. Whether it is for washing or cleaning, it is something we all need, and Fischer have found air source technology to be an extremely efficient way to heat water. As domestic hot water does not need to be provided at extremely high temperatures, the Fischer Aquafficient Eco+ uses air from within your home to generate heat and provide hot water to your showers, baths, sinks and other hot water appliances at up to 65 degrees centigrade.

Taking an Aquafficient Eco+ 300L model as an example, the COP ranges from 2.5-3.7, depending on the power input.

Although air source heat pumps are not a one-size-fits all, that is not to say they aren’t suitable for some properties. However, the wider majority of homes, especially older properties, are not suitable, and would be better suited to independent electric radiators.

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