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At its most basic, a heat pump is a energy efficient appliance that extracts heat from one place and transfers it to another. It is not new technology and has been used in devices like refrigerators and air conditioners for decades. However, in recent years, an improvement in the efficiency of heat pumps has also made them an option for home heating.
Last update: March 2021
Around 86% of all homes in the UK use natural gas to keep warm and heat the water. That’s about 23 million houses and apartments across the country. But, as we well know, gas is not available in infinite supply and we need to start transitioning to more sustainable forms of energy. Which is where heat pumps come in.
A heat pump is a sustainable way of taking latent heat from the air, water or ground around us and using it to heat or cool homes, provide hot water and run central heating systems. The technology behind the heat pump is not new but technological improvements have made it a more viable option in recent years.
Although not suitable for every home, a heat pump could be a solution for many in the UK. Installation costs can be high but it is possible to make savings of around 50% on your current energy bills for heating and hot water. Over the years this will really add up. Plus, government grants and support is available to help with the costs.
So, if it sounds like a good idea for your home, keep reading to find out more.
How do heat pumps work?
Heat pumps work by transferring heat through circulating a substance called a refrigerant through a cycle of evaporation and condensation. It is pumped between two heat exchanger coils and in the first it is evaporated at low pressure where it absorbs heat from its surroundings. The refrigerant is then condensed at high pressure in the other coil releasing heat it has absorbed in earlier stages of the cycle.
Where a fridge uses an insulated box and removes the heat from inside, a heat pump system removes heat from the air outside and pumps it into a building. Kind of like a big reverse refrigerator. Of course, this process can also be reversed, removing heat from the building and replacing it with cooler air. That means a heat pump system can be used as a year round temperature control system and air conditioning system for your property.
Heat can be pulled from the air, even at very cold temperatures, In fact, -18˚air has 85% of the heat contained at +25˚. So, even when it is very cold outside, you can still draw warmth into your home.
What are the different types of heat pump?
There are three main types of heat pump:
- Water source
Air source is the most commonly used and one of the most inexpensive to install. They work best in moderate climates using the outside air temperature to draw in heat. Water source heat pumps require a large source of water such as a well, lake or storage tank. As such they aren’t so commonly used for domestic use.
Ground source or geothermal heat pumps transfer heat in a similar way to air-to-air pumps but using heat stored underground. As the ground temperature is at a more constant temperature they offer more efficient operation but installation can be much more expensive.
However, as well as the above, there are also some sub-types of heat pump, such as:
- Hybrid heat pumps: including ground and air source combinations as well as heat pump and gas and oil boilers
- Solar heat pumps
- Absorption or gas fired heat pumps
What are the advantages of a heat pump?
There are many advantages of installing a heat pump system in your home over more traditional heating methods. These include:
- Lower running costs
- Less maintenance
- Improved safety
- Lower carbon emissions
- Heating and cooling
- Long life span
What are the disadvantages of a heat pump?
However, it’s not all good news. There are a number of major disadvantages of installing a heat pump. These include:
- High up-front costs
- Can be challenging to install
- Issues around sustainability
- Lots of disruption when installing
- Less efficient in colder weather
- Planning permission may be needed
How much does it cost to install a heat pump?
Heat pumps are not cheap so you need to think carefully and do your sums before making the investment. The total cost will depend on the size and the area needed for the installation, based on the size of your home and heating needs.
Ground source heat pumps cost anything between £11,000 and £15,000, due largely to the required installation of the pipes under the ground. This usually requires digging and earth works, so will cost more for an existing property than a new one. If installed correctly, they can save you money on your heating bills. So, you need to work out if you can make your money back over time.
Air source heat pumps cost around half that, usually between £5000 and £8000 depending on size and heating needs.
Water source heat pumps are also expensive, costing between £20,000 and £30,000.
Can a heat pump heat the whole house?
In most cases, heat pumps can heat the entire home as well as providing hot water for your bathroom and kitchen. However, they will work more effectively in open plan and single-story buildings.
New technology such as heating control zones and smart thermostats have made heating the whole house with a heat pump a more viable option. There has been a growing trend towards a more whole house solution design in recent years, with larger units and more heating ducts being installed to cover the whole building.
At what temperature is a heat pump no longer effective?
You might think that in order for it to work the air outside needs to be hot but that is not how it works. Even very cold air stores heat. As we mentioned above, air that is -18˚ still contains about 85% of the heat of air at +25˚. A heat pump can remove this warmth from very cold air and turn it into hot air.
In the UK, the temperature rarely drops below around -10˚. And with heat pumps being able to work until temperatures of -20˚, a heat pump is a good option for your home. However, at colder temperatures the heat pump becomes less efficient and has to work harder to heat your home, so think about where you position your pump units.
What is a water source heat pump?
A water source heat pump is one that extracts heat from a large body of water such as a lake, well or large storage tank. They use a series of submerged pipes containing a working fluid to absorb heat from the water and transfer it into the air that heats your home.
The fact that you need a large body of consistent water nearby to use it means it is less commonly used for domestic heating.
Are there any heat pump grants and incentives?
There are two different types of programmes provided by the government to aid the installation of renewable heat systems. One is the Domestic Renewable Heat Incentive (RHI) scheme, which is aimed at homeowners, social and private landlords, and also to self-builders. You may be applicable for this scheme and you can find out more about it here.
The Non-Domestic Renewable Heat Incentive is open to the public sector such as businesses, organisations and industries. If you are thinking about using a heat pump for your business then you may qualify under this scheme.
What are the best brands of heat pump?
There are a number or popular brand names for heat pump manufacture in the UK. These include:
Any of the above would provide you with a reliable system for heating your home and water. But new players are entering the market all the time, sensing that heat pumps are going to be a popular way of heating homes for the future.
Factors to consider when buying a heat pump
Before you make the decision to buy a heat pump, there are a number of things you need to think about. The first is how much you want to spend up front. Yes, a heat pump will allow you to make big savings over time and recoup your investment. But the initial outlay still involves spending a large sum of money.
The size and type of system you require will inform this decision. And it’s also worth remembering that the higher end systems also have a longer service life in general.
You also need to decide what kind of heat pump you want. Will it be air-to-air, ground or water sourced or a dual fuel option? This decision depends on your location, circumstances and budget.
In addition, you need to think about extras such as the type of thermostat you need for your system and whether you need temperature zones across your building in order for it to be more efficient.
Maintenance of a heat pump
Like any complex machinery involved in heating or cooling, your heat pump will need a certain degree of maintenance. As always, prevention is better than cure so having a regular service is always recommended. A check up will involve checking all ducts and filters for dirt and obstructions. They will also be checked for leakages, airflow and refrigerant charge.
A heat pump engineer or your place of purchase should be able to carry out a check up and provide any repairs that you may require.
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Updated on 31 Mar, 2021