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What Size Air Source Heat Pump Do I Need?

what size air source heat pump

Are you considering purchasing an air source heat pump but you don’t know what size your household will need? Then look no further, as ZOA Eco Grants is here to help you.

Air source heat pumps are growing in popularity as households throughout the United Kingdom are looking for new ways to heat their homes with the impending phasing out of gas boilers. Not only are air heat pumps more environmentally friendly, but they could also reduce your energy bills and are more energy efficient than traditional boilers.

This article will explain: what an air source heat pump is, the pros and cons of heat pumps, how big they are, what size heat pump you will need, and the key influencing factors affecting heat pumps. 

What Is An Air Source Heat Pump?

An air source heat pump works by transferring heat from the air outside your home into water. This heated water is then used to raise the temperature inside your home, via your property’s radiators and underfloor heating. Not only that, an air source heat pump can also heat water which allows you to use hot water in your showers, baths, and taps.

Pros And Cons Of Air Source Heat Pumps

Benefits Of Having An Air Source Heat Pump Installed

Advantages of air source heat pumps
Benefit Explanation
More environmentally friendly Unlike your traditional boiler which will require fossil fuels to work, heat pumps use renewable energy sources which are more environmentally friendly. In turn, this will minimise your household’s carbon footprint.
Could reduce your energy bills Depending on the heating system you are replacing, installing a heat pump in your property may reduce your energy bills. If your property also features solar panels, you can use them to power your heat pump which can lead to greater savings.
More energy efficient Typically, air source heat pumps have an energy efficiency rating between 200% and 400%. This is significantly higher than combi and gas boilers which have an efficiency rating of 90%.
Protects you against future boiler bans Due to current government legislation, you will not find a gas boiler in a new build property after 2025. While gas boilers are expected to be phased out altogether by 2035. Installing a heat pump now will protect you from this change.

Drawbacks Of Having An Air Source Heat Pump Installed

Disadvantages of air source heat pumps
Drawback Explanation
High upfront cost Like any other heating system investment, there are large upfront costs associated with purchasing a heat pump.
Could lead to higher electricity bills While you may save money on your energy bills, there is also a chance that you will see an increase in your electricity bills, as this is what runs heat pumps. 
Less energy efficient in the winter months It is important to remember that heat pumps will still 100% work during the winter months. However, they will be less efficient which means they will require more electricity to provide your desired amount of heat.
Slower heat supply Gas boilers aim to provide rapid heat for your household. Heat pumps on the other hand are unable to match the speed in which a boiler can heat up your home, however it can work better to maintain it.

How Big Are Air Source Heat Pumps?

In terms of the electricity output of an air source heat pump, they typically range between 5 kWh to 16 kWh. Of course, the bigger your home is the greater size heat pump you will require. However, very large properties may not be suitable for air source heat pumps. Instead, ground source heat pumps may be more effective.

However, you may be curious about the size of air heat pumps, and how much floor space they may take up on your property. They will typically stand at 1 to 1.5 metres high, and 0.5 to 1 metre wide. On average air source heat pumps typically weigh between 60 kg to 100 kg.

 

What Size Air Pump Do I Need For My Home?

There are a variety of factors that can influence the size of heat pump your household requires, from the size of your property to the size of your radiators and underfloor heating system. Another major contributing factor is whether you live in a new build property or an older home.

If you live in a new-build, the figures detailed in the two tables below will give you a general idea as to what size heat pump your household will require. However, if you live in an older property, we advise having your home analysed by an engineer to ensure you purchase the right size heat pump for your property. This is a service we offer here at ZOA Eco Grants.

What size air pump do I need to heat my home with poor insulation?
House size Recommended air source heat pump output
2 bedroom house 6 kWh
3 bedroom house 7.5 kWh
4 bedroom house 15 kWh
5 bedroom house 16 kWh

However, if your home features the necessary insulation to maximise the effectiveness of an air source heat pump, you may require a smaller heat pump. This could not only save you a significant amount of money, but will also minimise the amount of space the heat pump will take up.

What size air pump do I need to heat my home with good insulation?
House size Recommended air source heat pump output
2 bedroom house 4 kWh
3 bedroom house 5 kWh
4 bedroom house 10 kWh
5 bedroom house 16 kWh

 

Why Does The Size Of A Heat Pump Matter?

Ensuring that you have correct heat pump sizing calculations is pivotal to maximising your return on investment. If you purchase a heat pump too small, your household will not be able to heat itself effectively. But if you purchase a heat pump size that’s too big for your household, not only would you have wasted money on your initial investment but also the running costs will be higher than necessary.

Additionally, the various heat pump sizes are designed to match different size houses. If your heat pump is too small it will be running constantly which will shorten the lifespan of the machine. On the other hand, having one that is too big will make the heat pump run on shorter cycles which will also reduce the lifespan of the pump. Therefore the size of your heat pump, and ensuring it meets your needs, is incredibly important.

Factors That Will Affect The Size Of Heat Pump You Will Need

There are a variety of factors that can influence the size of the heat pump system that your household may require. Ensuring that your home doesn’t experience any heat loss in the transition from your gas boiler to an air source heat pump system is important. So, you should take the following factors into account.

Outdoor Temperature

Understanding the outdoor and indoor temperatures, and how they impact how an air source heat pump works, is key to getting the most out of your new renewable heating system. In order to extract heat from the outside air, the pump passes refrigerant liquid through heat exchanger coils. With a high temperature, this process is made easier compared to when we are experiencing the coldest air temperatures outdoors.

To ensure your air source heat pump will work all year round, the system is designed to operate in the coldest air temperature that you will experience in your local area.

Home Insulation

If you live in a poorly insulated house, or your home does not meet the minimum insulation levels required for air source heat pumps to work effectively, it may not be suitable. You may need to improve the insulation in your loft and walls before installing a heat pump, as your house will struggle to retain the heat that the air heat pump is providing your home.

 

Size Of Your Radiators

Similar to home insulation, if your home does not feature large enough radiators to heat your home then your air source heat pump may not work as effectively. Where gas boilers can heat your home rapidly, heat pumps work slower, which increases your reliance on your radiators.

Desired Temperature

Everyone has a desired room temperature they wish their home to retain. However, the higher heat demand you have on your air source heat pump, the larger the system you will need. By compromising on the desired room temperature of your home, by choosing lower room temperatures, you can save money.

Flow Temperature

Flow temperatures relate to the temperature required for water to be able to circulate around your radiators in your home. Key influencing factors that can impact your flow temperature include: the size of your radiators, the level of insulation in your home, and whether you have any underfloor heating.

Hot Water Cylinder

A hot water cylinder is an important element of the air source heat pump system. This is because the hot water that your household requires will be stored in this cylinder which will also contain a coil designed to heat said water. To ensure that your household’s hot water needs are met, you need to work out how much water your household uses. The figures in the table below should help you.

How much water does your household use?
Water usage Average water needs per person per day
Low use 20 to 30 litres
Average use 30 to 50 litres
High use 50 to 70 litres

Once you have worked out how many litres your household uses, you should be able to purchase the right size hot water cylinder.

 

What Size Air Source Heat Pump Do I Need Summary

With the end of gas boilers in sight, air source heat pumps are one of the heating systems for the future. The benefits of air heat pumps are also substantial, from a reduction in your energy bills to minimising your household’s carbon footprint. 

In the table below, we have outlined what size air source heat pump your household will require if you live in a new-build. If you live in an older property, we advise having an engineer analyse your property beforehand.

What size air source heat pump do I require?
House size Recommended air source heat pump with poor insulation levels Recommended air source heat pump with high insulation levels
2 bedroom house 6 kWh 4 kWh
3 bedroom house 7.5 kWh 5 kWh
4 bedroom house 15 kWh 10 kWh
5 bedroom house 16 kWh 16 kWh

If you need further help finding out what size heat pump you need or you want to apply for an air source heat pump grant, then why not get in touch with ZOA Eco Grants? Our heat pump experts will be able to answer any questions you may have.

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