Air Source Heat Pumps
Air source heat pumps are one of three types of renewable energy generator that absorb heat from sustainable sources (in this case, the air) and pump it through a compressor to increase temperature before using it to heat homes and small businesses. The other types of generator belonging to the pump family are ground source and water source heat pumps.
As with other pump technology, uptake of the system has been much slower in the UK than in others parts of Europe, although popularity is starting to increase, partly due to the renewed interest in renewable energy by the government and the implementation of a number of new schemes designed to make switching to green living simpler and more affordable.
How do they work?
An air source heat pump has quite a simple system compared to other devices. It includes a compressor, a heat exchanger and an evaporator coil. They are quite easy to install as well and simply take out heat from the air around it even if it is minus 15 degrees, so it can work in most climates. It carries this heat along to the heating system or fan, depending on which you have within your property.
Advantages of Air Source Heat Pumps
By far the biggest advance of an air source heat pump is the reduced pollution. Depending on the size and the efficiency of a pump, the average UK household could see their carbon emissions slashed by 800 to 5410 kilograms.
Unlike ground source heat pumps, air source heat pumps are easy to install and don't take up nearly as much room, making them suitable for even the smallest of gardens. All that's needed is a mountable wall (preferably in a spot that sees some daily sunlight, although that's not always possible with the unpredictable British weather!).
Once an air source heat pump is fitted, that's it. It won't require babysitting and, in most cases, shouldn't be temperamental. It should really have a quick service once a year, although many owners get it checked out professionally just once every 3 or 4 years (it's important to get this done to make sure antifreeze levels are adequate - you don't want your pipes freezing up!). The life span of a pump is roughly 20 years, and a 10 year warranty is considered normal, which backs up the fact that they're incredibly resilient.
Disadvantages of Air Source Heat Pumps
The biggest issue with air source heat pumps is that they're really nowhere near as efficient as other forms of sustainable energy system, even the other types of heat pumps. Not only do they generally just not function as well, it's been found that around half of all installations have airflow problems, whether that be air leaks or dodgy refrigeration.
With these issues, the question arises as to if these systems can truly qualify as renewable energy technology. Performance issues continue to be looked into. They also require electricity to run, so will never be entirely carbon neutral, unlike solar panels.
Planning permission is required in Wales and Northern Ireland, and may be required in England and Scotland depending on location and size of the system. This could prolong the process and applying for permission adds time and effort to what could be a much easier and quicker installation.
When absorbing energy from the air, tests have found that it's rather complicated to accurately measure the absorption rates in terms of energy production, and research has generally shown figures that just don't add up. For this reason, finding funding for these systems is much more difficult than for other systems, and business are currently not able to claim financial assistance from the government run Renewable Heat Incentive scheme.
The compression process, although effective in raising temperatures, will be unable to provide heats equal to that of a conventional boiler and gas central heating system. It's thought to take up to three times longer to adequately heat a property, and homes must be well insulated to benefit from the full effect.
Can The Weather Affect Production?
Yes, although it doesn't have to be a deal breaker. While heat pumps are designed to work in colder climates, they will be much less efficient and as air source heat pumps are naturally around 15% less efficient than ground source heat pumps, this can make a rather substantial difference, especially as the winter is the time when the energy is really going to be needed.
Some air source heat pumps now come with internal boosters which aid production in cold weather, although these will cost significantly more than pumps without this additional technology. Air source heat pumps also have storage capacity, meaning homeowners should never find themselves without heat or power, even in the most severe of conditions.
Upfront & Ongoing Costs
The cost of an air source heat pump greatly depends on the size of the system and the amount of energy that's required, but a range of £5000 to £10000 is normal, which makes them one of the least expensive renewable energy systems available. You should find prices equal to approximately £500 per kWh. Running costs also vary, but the average household can expect to spend £400 to £500 per year on supplying electricity to the system.
Funding be be difficult to come by for reasons previously explored, but local authorities may be able to offer grants or loans to help with the upfront costs. Although Phase 1 of the Renewable Heat Incentive does not cover air source heat pump systems, it is expected that payments will be extended to owners of these systems with the roll out of Phase 2 scheduled for summer 2013.
How Much Can I Save?
Depending on the system that is being replaced, households could see a reduction in their annual heating bills of £130 to £610 on average. Based on a £5000 system, this could see the generator paying for itself within 9 years. If the Renewable Heat Incentive scheme extends to cover air source heat pumps, this could have a massive influence on savings.
Although tariffs for Phase 2 have not yet been confirmed, if the rates are similar to that of Phase 1, homeowners could see an additional £850 added to their annual income. Factoring in this payment, the initial costs could be cancelled out within just 4 years.