Pump it up

Max Halliwell of Mitsubishi Electric answers your questions on air source heat pumps and explains their particular benefits for self-builders

What is so good about air source heat pumps versus traditional heating options for self-builders?

The future of heating is renewable in the UK as shown by the Government’s recent re-commitment to the Renewable Heat Incentive (RHI), which saw a 33 per cent increase in the rates for air source heat pumps.

Because of this, self-builders installing an air source heat pump into their projects are eligible for 10.18 pence for every kWh of renewable heating their system produces, with up to seven years of payments from the Government.

If they also include a Metering & Monitoring System Package (MMSP), they can also receive an additional £1,609 over the course of the RHI.

Heat pumps are also more suited to the modern levels of insulation and building that self-builders need to achieve, which in turn allows the heating to run at lower temperatures, keeping running costs down and comfort levels high.

How have pumps improved over the years, didn’t they used to be bulky and noisy?

While we can’t speak for all heat pump manufacturers, our Ecodan range has been refined and improved since we launched it in the UK nearly 10 years ago. Today’s systems include advanced, inverter-driven technology which maximises efficiency levels to match the heating and hot water requirements.

Heat pumps are now designed to be quieter, with some models being endorsed by the Noise Abatement Society and achieving Quiet Mark accreditation. They can also include the latest smart controls that allow homeowners to control and monitor their heating from anywhere in the world.

Are the simple to use?

Modern air source heat pumps couldn’t be easier to operate. Whether this is from the optional wireless room controller or via an app, the heating and hot water can be programmed to automate your heating depending on the external weather, or remotely, for example from the airport, if you’ve forgotten to switch to ‘holiday mode’.

How much electricity do they tend to use in cold weather?

Air source heat pumps operate most efficiently at lower flow temperatures than gas and oil and are best suited to

continuous running. This means that your home stays warm all year round, regardless of the outside temperature. While this will need slightly more electricity in the colder months, the seasonal efficiency (SCOP) throughout the year will average out at 3.5 or more, meaning you get 2.5 or more ‘free’ heating energy from the outdoor air for every kilowatt of electricity you use.

Not only is this eligible for quarterly payments from the Renewable Heat Incentive, it contrasts sharply with the efficiency levels of gas and oil, which can never achieve better than 1.0.

How can smart controls help ensure you’re getting the best out of your air source heat pump once installed?

I’ve personally had an air source heat pump fitted to my 1950s semi (pictured) for the past six years and one of the things I love most is being able to see exactly how my system is performing on my smartphone.

Not only can I switch on the water or heating from afar, if I need to, I can also change the schedule depending on the weather to always make sure that my home is warm and cosy when I get home.

Are there any limitations on effectiveness for uk self-build properties?

We’ve got examples of air source heat pumps being installed in all types of buildings, from 300-year-old cottages, restored Victorian brick buildings, right through to modern, self-build projects or refurbished buildings like my own 1950s semi.

They can therefore be seen as ideal for just about any project, and the main consideration would be at the design stage to make sure that your heat pump is configured correctly to suit whatever heat transmitter you want to use, whether that is underfloor heating, traditional radiators, or a combination of both.

What are common pitfalls that self-builders can fall into when choosing air source heat pumps?

An air source heat pump will need to be installed outside, so the sound levels of the unit are an important consideration.

While this isn’t an issue for most self- build projects, it is worth looking at the sound levels from different manufacturers and also thinking about where you site the outdoor unit if you are building near to neighbours or windows.

It’s worth looking at the Quiet Mark website or asking the manufacturer what their noise levels are.

How do you go about securing RHI payments to help make things easier?

The Government has just announced a revision of the RHI which came into effect on 20 September. This sees the rate for air source heat pumps increase by 33 per cent to 10.18 pence per kWh. It is subject to a cap of 20,000 kWh per property, but this is something that is unlikely to affect the majority of self- build heat pump installs.

RHI payments depend on the installation and installer being MCS (Microgeneration Certification Scheme) registered before they can qualify. Choose an installer that is MCS- Accredited and ask their advice about the application.

How can you be sure your installers really know what they’re doing, as poor installation can mean the benefits are cancelled out?

All Ecodan installers have to have attended our extensive training programmes and all creditable manufacturers should operate similar training. If in doubt, contact the manufacturer first for advice on finding a suitable installer in your particular region.

What are three golden rules self-builders need to know if they’re keen to install an air source heat pump?

Firstly, use an appropriately qualified installer to design the system to suit your needs. As stated earlier, the installer and the installation will need to be MCS-accredited if you wish to apply for RHI payments.

Second, a complete new build project will less of a requirement for heating than a refurbished property but will still have the same requirements for hot water. There are air source heat pumps which are designed specifically for this purpose. There are also units which are more suitable for properties with a higher heat load.

Lastly, most modern air source heat pumps should include internet-based controls and should be both straightforward to use and easy to understand but always make sure you also receive training on how to control the system from the installer.

Max Halliwell is a renewable heating expert at Mitsubishi Electric