Heating and Ventilating

The Government must move quickly to put right the serious market distortion caused by leaving air source heat pumps out of the Renewable Heat Incentive, says Scott Gleed
It is technical nonsense that air source heat pumps remain outside the Renewable Heat Incentive (RHI) when ground source heat pumps are included.

Air source products were excluded when the commercial RHI scheme got underway last October because the government said there was insufficient cost information to set an appropriate tariff. However, the government now has at least as much evidence about air source heat pumps as any of the technologies that already benefit from the RHI and there is no reason why it should now not be able to apply a tariff to exactly the same formula.

A number of experts have pointed out that the renewable market is developing at a much slower rate because of this unfair penalty on heat pumps. Despite the fact that it is a highly efficient, tried and tested technology, it is being overlooked in many applications where it should be specified because many, wrongly, interpret its omission from the RHI as casting doubt on its effectiveness.

Despite the RHI setback, it is clear that heat pumps will play an increasingly important part in reducing the carbon footprint of commercial and residential buildings in the long term. As the technology becomes more widely used, it will be more important than ever to focus on the quality of installations.

All heat pumps are covered by the F Gas Regulations. While mono blocks can be installed by a non F-Gas qualified engineer, all heat pumps must be serviced, maintained and decommissioned in accordance with the Regulations. Regular maintenance is needed to ensure systems stay efficient and regular leak checks are carried out. This will lead to reduced energy costs and ensure the systems last longer.

However, the important message to get over to end clients - whether domestic or commercial - is that properly trained, multi-skilled engineers are vital to their ambitions for reducing the carbon footprint of their buildings. Emerging markets can be a magnet for all sorts of fly by night firms looking to cash in. It is essential that only installers with a good grasp of the engineering principles are allowed to try and integrate 'new' solutions into buildings.

The importance of this was revealed in field trials carried out by the Energy Savings Trust (EST) in 2010. These appeared to show that heat pumps were not delivering their promised carbon and energy savings. Of 83 heat pump installations trialled only 13 per cent were found to have reached the target coefficient of performance (CoP) of three or above.

However, the EST was quick to point out that it did not believe there was any fundamental problem with the technology. 'The best performing systems show that well-designed and installed heat pumps can operate well in the UK,' its 'Getting Warmer' report said.

'A comparison between carbon emissions from heat pump installations and electric or gas heating (based on the UK Government's current predictions for grid decarbonisation) shows that a well installed heat pump can lead to carbon savings, both at present and over the lifetime of the pump.'

What the trials had revealed was that there were a range of installation and commissioning issues as well as confusion among end users about how to operate heat pumps. These issues were undermining good design and leading to very similar installations returning wildly different results.

The trials demonstrated just how important it is to prepare thoroughly to ensure the right type and capacity of unit is selected and also that local site conditions are taken into account before starting work. This shows that it is one thing to diversify into heat pumps, it is quite another to do it well.

Correct commissioning is crucial. Heat pumps need to be adjusted and tested once in place to ensure they are performing as intended. Squeezing commissioning time can lead to disaster as the EST report showed. Integrating a renewable system into an existing building with conventional services can be particularly tricky so requires expertise and time.

Ground source heat pumps (GSHPs) are, however, proving their worth in many projects and will produce coefficients of performance (COPs) of up to 4.5 depending on the flow temperatures achieved. However, they require a relatively high level of capital investment and so the installer has to thoroughly research the project in hand to make sure the investment can be justified.

While GSHPs are successfully serving the so-called 'top end' of the market, air source systems are ideally positioned for the mass market, which is why it is so important to iron out this RHI anomaly.

The evolution of this version of the technology means almost any type of home in the UK can now benefit from this energy and carbon saving approach, and they are particularly suited to smaller properties. Local authorities, for example, have been quick to recognise the potential in a system that can be retrofitted to smaller houses that were previously considered 'hard to treat' to improve their energy performance. RHI payments will offer just the right incentive to give this market a healthy boost in the private sector too.

Air source heat pumps offer excellent close control to maintain day and night time temperatures based on the prevailing ambient conditions. They are also far less complex than their ground source cousins as they are relatively easy to install and do not require large amounts of space in or around the property.

The availability of multi-split options, with one outdoor unit serving up to four indoor units, that deliver heating in the winter and cooling in the summer, makes them ideal for standard two-bedroom apartments as you can position one indoor unit in each bedroom, plus one in the lounge and one in the hall.

Ideally, air source heat pumps will become part of the RHI from this October for commercial installations and be included in the domestic scheme next year. The Government is aiming for at least 25,000 households to take up the RHI scheme in the first year, and its 'carbon budget' predicted a total market of 600,000 heat pump installations by 2020.

With the right additional training to supplement their already proven thermodynamic engineering skills, refrigeration and air conditioning contractors can make sure they are at the forefront of this fast emerging market.

The author is chairman of the B&ES Refrigeration, Air Conditioning and Heat Pump group