Air Source Heat Pumps (ASHP) – the Basics

You may have heard about Heat Pumps as the up and coming form of renewable heating technology. In theory the systems should be able to provide the whole heating for a building at little or no cost to the owner, with the added bonus of not using fuels to create the heat energy. Does it sound too good to be true? Or is it the future of heating?

It is important to acknowledge that there are two types of Heat Pumps, Ground Source Heat Pump and Air Source. Both have their own applications and both are more suitable for particular types of building and properties, depending on the requirements. This article aims to look at Air Source Heat Pumps and give an overview as to their benefits and drawbacks.

An Air Source Heat Pump absorbs and extracts heat from the outside air. It works in much the same way that a fridge extracts heat from the inside to keep it cool. This heat is used to heat the home via traditional methods such as radiators. It can even provide the hot water.

An Air Source Heat Pump is an external box, very similar to those utilised in an air conditioning system that needs to be positioned on a suitable, preferably sunny, external wall, which has a clear air flow and isn’t obstructed. Heat from the air flow is absorbed into a fluid which is pumped through a heat exchanger which is inside the actual Heat Pump. This heat is considered ‘low grade’ so it then passed through the heat pump compressor, which compresses it and concentrates it into a higher temperature ‘useful’ heat, which is capable of heating or providing hot water. The system can continue to extract the heat from the air even when the temperature is as low as minus 15 degrees Celsius.

There are two main types of air source heat pump available in the market.

Air to Water System: This uses a wet central heating system to distribute the heat and hot water. This is the most common system available because it uses existing technology in most households and buildings.Air to Air System: This distributes the heat using fan circulation throughout the property. Because this system uses hot air to heat the building it is less likely to provide the hot water as well.

Firstly, the Air Source Heat Pump is not entirely green. It relies on electricity to work and to keep the pump operational. Although it can lower fuel bills, the actual reductions can be less depending on the fuel type you are replacing. For example, if you have converted from electric heating the saving can be substantial, but from gas, less so.

The system also does not produce the level of heat that gas or oil boilers do. The Air Source Heat Pump delivers a lower temperature but over a much longer period. This means that during cold spells or the winter the heating may have to be left on all the time to heat the building efficiently. The radiators will never be hot to the touch like with a conventionally fuelled system.

To maximise the efficiency of an Air Source Heat Pump the building itself also needs to ensure that it is well insulated. Because the heat output is lower than with a conventionally fuelled system, the building needs to be well insulated and draught proofed to prevent heat loss.

Although there are little ongoing costs for maintenance, the user will have to ensure that the external Air Source unit is kept clean and the area surrounding it clear.

The initial installation costs can be very high, much higher than fitting a new conventional heating system on an existing building. However, the ongoing cost savings and efficiencies can far outweigh the initial costs. Fitting a Heat Pump into a newly built building can help to reduce the costs.

As previously mentioned having an Air Source Heat Pump can help to reduce fuel bills on a property and, by extension, can help to reduce your carbon footprint. As a user you won’t be reliant on fuel deliveries or combustible fuels, just the electricity to run the actual system. The unit is very low maintenance system, so ongoing servicing costs are much reduced.

In a world where conventional fuel sources are diminishing, Heat Pumps represent an excellent alternative. Although they do have drawbacks the benefits are substantial, both in long term cost savings and in carbon footprint reductions. It is definitely a technology to consider if you are looking for renewable technologies in the future!

Written by Symon Silvester

Photo by DaveBleasdale

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Grants and Funding Options for Commercial and Residential Geothermal Heat Pumps

All offices and homes need to have a heating and cooling system in place. Whether it is for a residential or a commercial setup, buying and installing heat pumps can be an expensive affair. The size of the system that is needed, the kind of technology it operates on as well as the complexity of the entire system are some of the various factors their price depends on. A general rule of thumb is that each kWth will cost around £1000. In the long run such systems can save a household as well as a commercial organization up to £840.

Heat pumps are a green system of generating heat. These models are based on air or ground sources, which work at extracting heat from the ground or the surrounding air. Going green is a noble cause and one that should be encouraged. The UK government has come up with several schemes in order to promote such instalments.

For commercial set ups, some of the schemes that you can consider are the Renewable Heat Incentive (RHI) where £860 million is going to be put towards commercial as well as residential heating operations in a two-phased process. Another is the Community Sustainable Energy Programme (CSEP), which is working towards creating awareness as well as supporting the cause of renewable energy. The funds will be diverted towards NGOs working for the cause. Feed-in Tariffs will allow people to claim and collected payments for the low carbon electricity they create. This will be for up to 5W generated at the spot for a period of 25 years.

The Enhanced Capital Allowance (ECA) allows any business to claim up to 100% of its capital allowance for the first year of implementation. These can be claimed as taxable profits. The Carbon Reduction Commitment (CRC) is a regulatory scheme that will encourage energy efficiency. This scheme has been in force since April of 2010. Esco Funding is where third parties involved completely involved in energy management. They help you create models for energy management as well the needed funding from the right sources.

When it comes to the residential sector, besides the RHI as well as Feed-In Tariffs, there is Scottish Community & Household Renewable Initiative (SCHRI), which is the counterpart of the Scottish LCPB phase 1 scheme and gives up to £4000 towards the entire acquisition and instalment of a system. Homes can also decide to follow the norms of the Code for Sustainable Homes that is national standard and is voluntary. The pilot scheme allows people to install such heat pumps on a trial basis in their homes at no installation costs. The repayments are made over an extended period and they are often evened out with the savings they make from the entire set up.

These are just some of the various schemes that are available from the private sector as well as the government to help encourage heat pumps in commercial and residential set ups. Each region will also have its own set of incentives that you will be able to be a part of. Making the right enquiries will land you with the right grant or scheme.

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Renewable Technologies: Ground Source Heat Pumps

You might have heard of many of the new green technologies that are starting to become better known in the UK heating systems market. Technologies like Heat Pumps, Solar panels and Renewable fuels promise to help cut not only the reliance on our limited resources of oil and natural gas, but also help to cut the utility bills of the home owner. Are these promises justified? Can the home owner save money by using these new technologies? This article aims to look at one of the most prominent of the new technologies, Ground Source Heat Pumps.

Ground Source Heat Pumps are very much at the vanguard of the modern heating technologies but how does it work? Well, a Ground Source Heat Pump works by pumping and circulating a mixture of water and anti-freeze around a loop which is buried under the ground at a depth of around two meters down. At that depth, regardless of the weather conditions at the surface, the ground remains at a more or less constant temperature.

This loop is also called a ground loop. It can be laid in various ways, depending on the amount of land available and how much heat is required by the system. The longer the length the more heat that will be absorbed into the fluid that passes around the loop. The loop can be laid flat or coiled in trenches around the land, or in some cases depending on space, can be dug down vertically. As the fluid in the pipes passes through the loop it picks up the latent heat from the ground and absorbs it into the liquid.

When the liquid returns to the Heat Pump it is passed through a heat exchanger. Because this heat is only the same temperature as under the ground it is considered low grade. This heat alone would not be enough to heat the property sufficiently. So when it is passed through the heat exchanger it is compressed which helps to make the liquid hotter and therefore able to be utilised in heating water for use in heating and hot water. The original fluid which is now cooler passes back into the loop to repeat the process indefinitely.

Sounds easy? It is a surprisingly effective technology. It utilises the environment to generate heat and there is an indefinite supply. It can help to cut fuel bills considerably, especially if you are swapping from electric heating. It doesn’t require oil or gas fuels and it certainly doesn’t need much in the way of maintenance.

What about the drawbacks? Let’s be blunt here. This is not an entirely ‘green’ technology. It won’t eliminate your use of utilities as it does require electricity to keep the unit running. It also doesn’t heat your property to the kind of levels that you have come to expect with traditional heating systems. Because the latent heat, even when passed through the heat exchanger, tends to be a lower temperature than with a standard system the radiators tend to feel warm rather than hot. This means during the coldest periods the heating system will have to run continuously to maintain the overall ambient temperature.

The other factors which should be considered involve the level of insulation currently in the property. A Ground Source Heat Pump works best in conjunction with the correct level of insulation to supplement the heating system and to prevent the loss of the heat. The size of the land available is also a consideration as well as access for diggers that will be required to put in the trenches.

The biggest drawback is the expense of installing a system. Installing a new Ground Source Heat Pump, along with all the associated works, is much more expensive that installing a modern standard boiler system. Estimates give the average cost as somewhere between £5,000 to £20,000. This will put it out of the reach of most home owners and at the moment it is not on any particular grant or subsidy scheme for home owners. By necessity retro fitting this on an existing building will be more expensive than installing this when a building is being constructed. So expect more new buildings in the future to start using this technology. If you are considering installing the system you should always consult with your local authority as to what permissions, if any, you might require.

In time the costs will come down as the hardware becomes cheaper and more cost effective, but it will always remain at the higher end because of the labour intensive ground loops required. However, if you have the money and the option, then this is a great green technology to look at providing low cost and permanent heating and hot water, without the need to burn gas or oil.

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