Your Guide - Heat Pumps







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With the government incentivising the roll out of heat pumps across the UK, they are now becoming a viable option when replacing an old boiler. With heat pumps only relying on electricity to run and burning no fossil fuels, they are a low carbon alternative with enormous eco benefits.

A renovation is a good time to consider replacing your old boiler with a lower carbon alternative, however there are many things to consider before you commit to a heat pump in your home. We look in more detail about heat pumps, including the cost and what you need to consider before you buy one.

Air source heat pump by Vaillant

What Is A Heat Pump?

A heat pump does a similar job to a boiler in that it will provide heating and hot water to your home. However, how it goes about supplying the heat is very different, in terms of the process and how it works with your existing heating system.

A heat pump extracts thermal energy from either the air or ground outside of your home, moving it into a refrigerant which compresses the air to increase the temperature. A heat exchanger then extracts the heat, which is transferred to your home to provide hot water and heating.

In the UK there are either air source or ground source heat pumps, with the air source being more popular as they require less outdoor space, are cheaper to install and will require less disruption to your garden.

Although both boilers and heat pumps will provide your home with heating and hot water, there are huge differences between how they operate.

Where boilers produce high temperatures in a short time period, heat pumps are slower to heat up and provide a lower temperature. This makes boilers more effective when it's particularly cold and you need a high heat for a short period of time from a radiator. 

Do Heat Pumps Work With Existing Heating Systems?

Heat pumps will not necessarily work with your existing system and often require larger radiators to produce the same amount of heat from the traditional boiler. 

They supply a constant warm temperature rather than high temperature increase over a short period of time, meaning that small radiators won't be able to heat your home. As they deliver the heat slowly, they are best if you want to heat up your home gradually.

Heat pumps work particularly well with wet underfloor heating systems as they produce constant warm water rather than short bursts of hot water. With a floor covering a much larger area than a radiator, there is no need for hot temperatures. With more and more renovators installing wet underfloor heating, there is more opportunity for a heat pump to work effectively in the home.  

If you are replacing a combi boiler, then you will need a hot water cylinder. If you have a conventional boiler, tt's also likely that you will need a new hot water cyclinder that works effectively with a heat pump and provides adequate hot water.

What Types Of Heat Pumps Are There?

You can either opt for an air source or ground source heat pumps, where their mechanism for taking heat is either from the air or the ground.

In terms of installation, the air source heat pump will be a unit which is outside of the property, attached or near to the external wall. 

Ground source heat pumps require pipes to be installed under the ground and can be installed vertically or horizontally, leading to an internal unit. Although it's cheaper to lay the pipes horizontally, you will need the outdoor space to be around 3 times the size of your indoor floor space, so this is only really suitable for homes on large plots.

Where ground source heat pumps are more expensive to install than air source heat pumps, they are slightly more efficient to run in the long run and cope better in colder temperatures.

How Much Does A Heat Pump Cost To Install?

The cost of a heat pump will vary depending on many factors:

  • The preparation that is required to your existing system and home, including replacing the radiators or improving the insulation.
  • The size of your property, with larger homes requiring a pump with more capacity.
  • Whether you opt for an air source or ground source heat pump, with the additional cost of laying the pipework for a ground source heat pump. 
  • If your home is new or existing, with existing homes requiring more of an investment.

Air source heat pumps cost from £7,000 - £15,000, with the cheaper end for a small, new build property.

You should expect a ground source heat pump cost to be around £15,000 - £20,000, again the more expensive properties are larger and retrofit rather than a new build.

How Cost Effective Is A Heat Pump To Run?

Heat pumps are thought to be slightly more expensive to run than a conventional boiler, however with rising gas prices a heat pump could become as cost effective as a gas boiler.

How Well Does The Heat Pump Heat The Water?

With heat pumps generating heat at around 20 degrees cooler than a boiler, you will need to turn up the temperature of the hot water when running a shower or bath. 

When you are replacing your boiler with a heat pump, you will need a hot water cylinder that works well with a heat pump. As the heat pump will heat up the water at a lower temperature, you will need a water cylinder with more coils to bring the water up to the desired temperature.

What Are The Benefits Of A Heat Pump?

  • They are a low carbon alternative to a conventional gas heater, making them a far greener choice.
  • As they do not use gas, they are a safer option.
  • Some work as an air conditioning unit to remove heat when it's warm.

What Are The Disadvantages Of A Heat Pump?

  • They can be a challenge in urban properties where you lack outdoor space for either an air source heat pump unit or to lay the pipework for a ground source heat pump.
  • The upfront costs are high compared to a boiler.
  • As it's likely that your heating system needs to be replaced, there is a lot of disruption.
  • They can be a challenge to heat inefficient homes where any heat can be lost quicker than the heat pump can create it, which is common in old properties.
  • Currently fewer trades are available to service it, although this should change in the coming years.
  • Air source heat pumps create noise outside, which some may find annoying. Do note the noise is not supposed to be louder than a refrigerator.
  • In the coldest temperatures, even efficient homes may find the heat pump will struggle to provide them with adequate heating. So you may need a backup such as a hybrid or a wood burner.

How Long Should I Expect A Heat Pump To Last?

A modern heat pump should last for around 15 years', with some lasting up to 25 years' with regular maintenance.

Is A Heat Pump Right For Your Home?

Whether a heat pump is right for your home is dependent on a couple of factors; space, efficiency of your home and financial constraints.

You will need the space to install an air source heat pump which will be placed next to the external wall outside. Similarly, if you are opting for a ground source heat pump then you will need a large garden to lay the pipework. You will also need the internal space for the hot water cylinder.

You should only consider a heat pump as an option if your home is efficient, so make sure your home is well insulated, with older properties often being inefficient and difficult to heat.

Lastly, it is a financial investment that will add to your renovation costs, so you must be comfortable that the benefits far outweigh the cost.

Are There Any Government Incentives For Heat Pumps?

From April 2022, the government will be offering grants as part of the Boiler Upgrade Scheme, with ground source heat pumps getting a £6,000 grant and air source heat pumps £5,000. This is applicable in England & Wales, where homeowners in Scotland can access funding via Home Energy Scotland.

What Other Options Are There?

Hybrid heat pumps are an option if you live in a cold climate and can be used as a back up when it's particularly cold outside. They also work well in older properties that may struggle with insulation and heating the property throughout the year.

Lastly, as technology develops the cost of the heat pumps should improve, similarly you may find that newer heat pumps will be able to heat the building at a hotter temperature, therefore less of an upgrade to your current heating system may be required.

Published: February 1, 2022

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