Air Source Heat Pump

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What is an air source heat pump?

When it comes to installing a new central heating system most of us will immediately think of boilers, gas bills and getting an energy efficient model. However, boilers aren't the only way to heat your home and, thanks to central heating pumps and more specifically air heat source pumps, they’re not the most environmentally friendly way, either.

From 1 December 2011 the installation of an air source heat pump (ASHP) on domestic properties is considered to be permitted development, not needing an application for planning permission, provided ALL the limits and conditions are met.

Unlike traditional boilers, ASHPs harvest warmth from the air outside and use it to run your radiators or under-floor heating and give you hot water. Save up to £350 on your heating and water heating costs and reduce your CO2 emissions by up to 1.5 tonnes a year. What’s more, if you’re eligible you could receive a government renewable Heat Premium Payment of £1,300 if you install one before March 2014 or qualify for the Renewable Heat Incentive (RHI). Why not use our suitability survey to work out if this EcoRenew product is suitable for your home our prices start from just £8,200 including installation.

The main advantage of air source heat pumps over ground source heat pumps is their lower installation cost. A ground source heat pump requires a network of underground coils that is used to extract heat from the ground. By comparison, ASHPs extract the heat directly from the outside air and so avoid these potential problems.

How do air source heat pumps work?

Heat from the air is absorbed at low temperature into a fluid. This fluid then passes through a compressor where its temperature is increased, and transfers its higher temperature heat to the heating and hot water circuits of the house. There are two main types of ASHP system:

1. An air-to-water system distributes heat via your wet central heating system. Heat pumps work much more efficiently at a lower temperature than a standard boiler system would. So they are more suitable for underfloor heating systems or larger radiators, which give out heat at lower temperatures over longer periods of time.

2. An air-to-air system produces warm air which is circulated by fans to heat your home. They are unlikely to provide you with hot water well.

Air source heat pump

- Overview

As ASHPs simply move energy rather than creating it by burning fossil fuels, they are extremely efficient. For every 3KW of heat moved into the house by the heating pump, only 1 KW of electricity is consumed. This gives a perceived efficiency of performance by air source pumps of 300 %, sometimes stated as a Co-efficient of Performances (COP) of 3:1.

- Collecting the heat

The air source pump uses a fan to force air over a heat exchanger (simply a copper coil filled with refrigerant) to extract heat from the air.

- The Evaporator

The purpose of the Evaporator within the ASHP is to take the heat obtained by the heat exchanger and boil the refrigerant (which boils at approximately – 10 degrees C). The act of boiling turns the refrigerant into a vapour which is then transferred to the Compressor.

- The Compressor

The Compressor does exactly what its name suggests; vapour is compressed in volume and as its volume reduces, its temperature increases to levels between 75 and 125 degrees C. The gas is then fed through a heat exchanger within the heating pump.

- The Heat Exchanger

Forcing the hot gas across the cold water from the central heating system condenses the refrigerant back into a liquid. As it condenses its heat is passed into the heat exchanger which supplies the domestic hot water and powers the central heating system using the air source heat extracted originally.

- The Expansion Valve

To complete the closed circuit of the Air Source Heat Pump, the only thing which needs to be done is reduce the pressure of the condensed liquid. This is achieved via the expansion valve.

- The case for Air Source Heat Pumps

There are many advantages of Heat Pumps, not least the ability of Air Source Heat Pumps to extract heat from the surrounding air at temperatures as low as -25 degrees C (depending on the size of the heating pump installed). Other heating systems could well struggle at these lower temperatures but with air source pumps, you can be sure of a warm and comfortable environment for you and your family.

The benefits of air source heat pumps

Air source heat pumps (also known as ASHPs):

- Could lower your energy bills, especially if you are replacing conventional electric heating.

- Could provide you with an income through the government’s Renewable Heat Incentive (RHI)

- Could lower your home’s carbon emissions, depending on which fuel you are replacing

- Don’t need fuel deliveries

- Can heat your home and provide and hot water

- Need little maintenance – they’re called ‘fit and forget’ technology

- Can be easier to install than a ground source heat pump, though efficiency may be lower.

Unlike gas and oil boilers, heat pumps deliver heat at lower temperatures over much longer periods. During the winter they may need to be on constantly to heat your home efficiently. You will also notice that radiators won’t feel as hot to the touch as they might do when you are using a gas or oil boiler.

Other benefits of ASHPs over conventional boilers include no combustion or explosive gases within the building, no need for flues or ventilation, no local pollution (although noise from the external unit fan maybe a problem), long life expectancy, and low maintenance costs.

Costs

Installing a typical ASHP system costs around £7,000 to £14,000. Running costs will vary depending on a number of factors – including the size of your home, and how well insulated it is, and what room temperatures you are aiming to achieve.

Savings

How much you can save will depend on your current heating system, as well as what you are replacing the ASHP with. Your savings will be affected by:

- Your heat distribution system

If you have the opportunity, underfloor heating can be more efficient than radiators because the water doesn't need to be so hot. If underfloor heating isn't possible, use the largest radiators you can. Your installer should be able to advise on this.

- Your fuel costs

You will still have to pay fuel bills with a heat pump because it is powered by electricity, buy you will save on the fuel you are replacing. If the fuel you are replacing is expensive you are more likely to make a saving.

- Your old heating system

If your old heating system was inefficient, you are more likely to see lower running costs with a new heat pump.

- Water heating

If the heat pump is providing hot water then this could limit the overall efficiency. You might want to consider solar water heating to provide hot water in the summer and help keep your heat pump efficiency up.

- Using the controls

Learn how to control the system so you can get the most out of it. You will probably need to set the heating to come on for longer hours, but you might be able to set the thermostat lower and still feel comfortable. Your installer should explain to you how to control the system so you can use it most effectively.

Earnings

You may be able to receive payments for the heat you generate using a heat pump through the government’s Renewable Heat Incentive (RHI). For systems installed after 1 August 2011, you may be able to get help with the installation costs of a new air source heat pump through the Renewable heat Premium Payment scheme.

How green are air source heat pumps?

An air source heat pump system can help to lower your carbon footprint as it uses a renewable, natural source of heat – air. The amount of CO2 you’ll save depends on the fuel you are replacing. For example, it will be higher if you are replacing electric heating than natural gas.

A heat pump also requires a supplementary source of power, usually electricity, to power to heat pump so there will still be some resulting CO2 emissions.

Is an ASHP suitable for me?

To tell if an ASHP is right for you, there are a few key questions to consider:

- Do you have somewhere to put it? You’ll need a place outside your home where a unit can be fitted to a wall or placed on the ground. It will need plenty of space around it to get a good air supply. A sunny wall is ideal.

- Is your home well insulated? Since air source heat pump work best when producing heat at a lower temperature than traditional boilers, it’s essential that your home is insulted and draught-proofed well for the heating system to be effective. If you home needs better loft and wall insulation than you may be able to get free Green Deal insulation with Green Deal Upgrade.

- What fuel will you be replacing? The system will pay for itself much more quickly if it’s replacing an electricity or coal heating system. Heat pumps may not be the best option for homes using mains gas.

- What type of heating system will you use? ASHPs can perform better with underfloor heating systems or warm air heating than with radiator-based systems because of the lower water temperatures required.

- Is the system intended for a new development? Combining the installation with other building work can reduce the cost of installing the system.

Call 01157012030 or fill in the form to the right for more info on installing an ASHP at your property through the Green Deal scheme and advice on what is best for you and your property