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Your Comprehensive Guide To Heat Pumps

Renewable energy and heating

When talking about renewable energy sources, we mean that the source is replenished naturally when it’s used.  Renewable energy is often also referred to as ‘green energy’ and ‘sustainable energy’.  Heat pumps can be used as a method of heating buildings and providing hot water, the heat comes from renewable sources: air, ground or water.  These sources are renewable because the heat’s ultimate source is the sun, which is constantly heating the earth and its atmosphere.  They do need electricity to operate, so do have some impact on the environment.

Choosing renewable energy is the ‘green’ option.  It reduces your impact on the environment and your dependence on non-renewable energy.  Heat pump systems can also help to lower your energy bills, and there are government financial incentives available.

In this guide we will tell you about measures you can take to improve your home’s energy efficiency, explain how heat pumps work and how you can benefit from them, as well as providing advice and tips in relation to heat pumps.

Home improvement to improve energy rating

Every domestic and commercial building that is available to buy or rent in the UK needs to have an Energy Performance Certificate or EPC.  The EPC grades the building’s energy efficiency and gives prospective purchasers, leaseholders and tenants an indication of how much it will cost them in energy bills if they take on the property.

The EPC also suggests ways that energy efficiency can be improved and what the building’s energy rating could be should these measures be implemented.  The grading goes from A to G, with A being the most efficient.  Homeowners can choose to have an energy performance survey undertaken to learn how they can make improvements that will reduce their energy bills.


Insulation helps to keep warmth from leaking out of your house and reducing its energy efficiency.  An insulated home will take less energy to heat because it will not cool down as quickly so you’ll be maintaining the temperature rather than heating a cold house.

The Energy Saving Trust1 recommend that loft insulation should be at least 270mm (11 inches) thick.  They state that you could save up to £180 a year in heating bills (if your loft is currently uninsulated).  If you already have loft insulation it may not be thick enough, topping up from 100mm to 270mm could save you around £25 a year.

If your house has wall cavities, which is likely if it was built after 1920, this space could be filled with insulating material.  This costs about £450 to £500 but can save you up to £140 a year, meaning that it pays for itself in around 4 years.

A very cost effective method of insulating your home is to draught proof it.  You can buy draught strips to affix around your windows and doors to prevent heat from escaping and the cold from getting in.  In an older property, you could also benefit from sealing any cracks in your floorboards, using sealant around your skirting boards and fitting a draught excluder on your letterbox.  All of these measures are cheap to implement and will help to reduce your energy bills and make your heating more efficient.

Type of heating system used

The type of space heating you have in your property will affect your property’s energy performance rating.  The score for heating is not just based on efficiency but cost.

Boilers and radiators is a common heating system.  Mains gas-fired boilers have low carbon emissions and, with current energy prices, is usually the most cost effective method of space heating.  Modern gas and oil boilers are more efficient than older models.  Electric heating is one of the most expensive heating options.  Electric storage heaters can be a little cheaper than conventional electric heaters because they tend to make use of Economy 7 tariffs, although they emit more carbon dioxide than most and are usually harder to control, temperature-wise, than radiators.

Installing heat pump systems will save you most money and reduce carbon dioxide emissions when you are replacing electric, oil, LPG or coal heating systems.  If you are replacing gas fuelled heating systems, you should still see a reduction in your carbon emissions, reducing your carbon footprint, but you are less likely to see a large financial saving.

Heat pumps perform best with slow response, low temperature heating systems, for example under-floor heating as opposed to traditional radiators.  If your home heats up and cools down quickly, a heat pump may not be the best option as it is not likely to provide enough heating for your home.  Before installing a heat pump you will need to insulate your home as much as possible and reduce any draughts.

Reduce your carbon footprint

When fossil fuels, such as oil, gas and coal, are burnt, carbon dioxide is released into the atmosphere.  Your carbon footprint is your individual effect on carbon emissions, which depends on the electricity and fuel you use.  The major contributors to your carbon emissions are: the energy used to heat your home; the electronics and appliances you use; the transport you use each day; and how often you fly.

If you want to reduce your impact on the environment, you can start by reducing your carbon footprint.  This can be done by insulating your home, using more energy-efficient appliances and heating systems, and making small changes, such as turning electricals off at the plug, using your washing machine at 30 degrees, and using energy efficient lightbulbs.

According to Energy Saving Trust2, “In 2010 the UK produced 496 million tonnes of carbon dioxide.  Some of this is produced by business and industry – but around 30% comes directly from the household energy use.”

“By making UK households more energy efficient and by reducing our transport energy consumption we can make big reductions in the UK’s carbon dioxide emissions.”

Reducing your carbon footprint can also help to reduce your energy bills.  So you’re not only helping the environment, but your pocket as well.

Financial incentives

Heat pumps are a large financial commitment.  You are likely to save money in the long run, but the payback period can be quite long.  To help you cover the costs, the government have put in place a number of financial incentives.

The Green Deal

This scheme allows homeowners to pay for installing energy efficiency improvements by spreading the cost over a number of years.  The payments are added to the householder’s regular energy bills.  The idea is that the charges will be offset by the reduction in energy bills. ***Please note the Green Deal is no longer open for new applications. See the DECC blog for more information.***

The Renewable Heat Incentive Tariff

From 9th April 2014, domestic householders will be able to apply for the Renewable Heat Incentive (RHI) tariff, whereby they will receive a payment for each unit (kilowatt hour or kWh) of green energy produced for 7 years.  Homeowners will need to satisfy the eligibility criteria, which includes the installation being certified under the Microgeneration Certification Scheme (MCS), and all applicants must have a ‘Green Deal’ assessment carried out on their home.  All heat pumps installed by the Reina Group are MCS certified; we are also fully certified to install the systems.

Heat pump systems

The two main types of heat pump systems are air source heat pumps and ground source heat pumps, each works in a similar manner but with its own nuances.

Air source heat pumps

Air source heat pumps work by extracting warmth from the atmosphere.  The unit is fitted outside the house where it has an unrestricted air flow.  Inside the unit is a fan that draws in air, which runs over liquid filled tubes.  The liquid, a water and antifreeze mixture, absorbs the warmth from the air and evaporates into a gas.  This gas is compressed by an electric motor-driven compressor, causing it to heat up.  A heat exchanger takes this generated heat and transfers it into your home’s heating system.  At this point the vapour loses its heat, therefore condensing back into liquid form and is once more able to circulate through the heat source.

The most common type of air source heat pump is an air-to-water system, which connect up to a wet central heating system, although air-to-air systems, which pump out hot air are also available.  These air-to-air systems can often be reversed to be used for cooling.

Benefits of air source heat pumps

Air source heat pumps can be easily incorporated into most UK homes.  You can either use them with under-floor heating or large radiators.  They are ideally suited to more modern properties, although they can be fitted in older properties as long as they are highly insulated and free from draughts.  This is because heat pumps work at lower temperatures than conventional heating systems.  Heat pumps keep a house warm, rather than heating up a cold house twice a day.

Costs & savings

A typical air source heat pump costs3 in the range of £6,000 to £10,000, The running costs will depend on the size of your property, how well insulated your property is and your heating pattern.

The Energy Saving Trust states that for a typical 3 bedroom semi with reasonable insulation, space and water heating could cost approximately £850 per year, based on current energy prices.  You are only likely to see savings if you are replacing a coal, oil, LPG or electric heating system.

How much you can save will depend on a number of factors including:

●      whether you use under-floor heating or radiators

●      how much your fuel is currently costing

●      how efficient your old system was

●      if the heat pump is also providing hot water

●      how well you use the system controls.


The data for the below table is taken from the Energy Saving Trust3:


Existing systemAir source heat pump performing at 300%
GasSavings £/year

Carbon dioxide/year



ElectricSavings £/year

Carbon dioxide/year



OilSavings £/year

Carbon dioxide/year



SolidSavings £/year

Carbon dioxide/year



Air source heat pumps can be more than 100% efficient because they generate more energy than they use to operate.

Using the RHI

The Renewable Heat Incentive (RHI) is a financial scheme set up by the Government to support those who use renewable heating systems.  The scheme became live for domestic householders on April 9th 2014.  Owners of heating systems, who meet the eligibility criteria, will receive a set rate per unit of renewable heat produced (kilowatt hour or kWh) for seven years.  The current rate for air source heat pumps is 7.42p per kWh of renewable heat.  The tariff will be reviewed annually in line with the Retail Price Index.


Air source heat pumps require regular scheduled maintenance to ensure that they are in full working order.  You will need to conduct an annual service by a professional installer as detailed within the RHI.  The annual checks are likely to include checking that the air inlet grill and evaporator are free damage, leaves and other debris, and removing any plants that may have grown too close to the unit as well as standard service criteria.

Keeping your heat pump in good working condition will increase help it to last and keep its performance as efficient as possible.


Ground source heat pumps

Ground source heat pumps collect warmth from the ground, which absorbs heat from the sun.  A water and antifreeze mixture circulates through lengths of plastic piping that is buried underground.  This fluid absorbs heat from the ground and evaporates into a gas.  Within the ground source heat pump unit is a compressor driven by an electric motor, which compresses the gas causing it to heat up, this heat is absorbed through a heat exchange into your home’s heating system.  Once this heat has been removed, the gas condenses into liquid form and is able to continue circulating through the coils of piping, repeating the process.

Benefits of ground source heat pumps

Ground source heat pumps generate less noise than air source heat pumps because there is no fan.  The unit can also be placed inside.  You can choose to have the collection loop either installed horizontally or vertically, depending on how much land you have.

Ground source heat pumps are suitable for people who have a garden, with ground suitable for either digging a trench or drilling a borehole.  If you are undertaking other building work, such as an extension, installing a ground source heat pump at the same time can reduce costs and disruption.

Costs & savings

The Energy Saving Trust say that ground source heat pumps typically cost4 £9,000 to £17,000, not including the cost of the heat distribution system.  Horizontal trenches can cost less, although you need more land; The borehole method allows you to benefit from site boundary constraints, although this comes with higher installation costs.

Any possible savings will depend on a number of factors including:

●      whether you have under-floor heating or radiators

●      your current fuel costs

●      the efficiency of your old heating system

●      whether you are using the heat pump to provide water heating in addition to heating

●      how well you control the system.

Ground source heat pumps can be more than 100% efficient because they generate more energy than they use to operate. Ground source heat pumps run at a higher efficiency than air source heat pumps.

Using the RHI

From 9th April 2014, the government’s Renewable Heat Incentive (RHI) became available to homeowners in England, Wales and Scotland. Owners of renewable heating systems will receive a set rate of financial support per unit of renewable heat produced; the unit is kilowatt hour or kWh.  This tariff will be paid for 7 years and aims to support those who choose renewable heating options for their homes.  The current rate for ground source heat pumps is 19.1p per kWh of renewable heat produced.  The tariff will be reviewed annually in line with the Retail Price Index. If you would like to get an idea of Renewable Heat Incentive payment you may qualify for, please use our  RHI calculator tool .


To ensure the longevity of your ground source heat pump and ensure that it keeps working at maximum efficiency, it is necessary to carry out regular maintenance.  This is made up of an annual check by you, and a more detailed check carried out by a professional installation engineer every 3 to 5 years.


Heat pumps are more energy efficient than conventional methods of heating your home.  They work most efficiently in a property that is almost ‘air tight’ with no draughts and with excellent insulation.  If you are looking to make home improvements in order to reduce your carbon footprint and reduce your energy bills, heat pumps offer an excellent solution.  They are suitable for a large number of properties in the UK.  Homeowners who are not currently on mains gas will see the most benefit from heat pumps because of the lower cost of gas compared to electricity.


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