Like thousands of other British homeowners, you may have caught the recent E.ON ad for heat pumps currently playing on TV.
But with its city streets turned into swimming pools, this slick, stylised advert feels a little continental. Can the tech really hold up to the realities of a UK winter, when there’s frost on the ground and ice on the windscreen?
Heat pumps will still appear new to many viewers, but they’ve been used effectively in the UK for over a decade. We’ve been manufacturing air source heat pumps (ASHPs) in Scotland since 2008. So, what exactly are they and will they be the right fit for your project?
We all use heat pumps already – we just know them by a different name.
You no doubt have a fridge sitting in your kitchen, quietly and reliably keeping your food cold and fresh. This appliance takes advantage of a vapour compression cycle, using the lower boiling temperatures of different refrigerant gases to extract heat energy from the food and transfer it away from the interior of the cooling chamber.
An air source heat pump does the same thing in reverse to harvest free heat energy from the outdoor air. Even in freezing conditions, ASHPs take a few degrees of warmth from the air and upgrade it via the vapour compression cycle to deliver all the heating and hot water a home needs, 365 days a year.
Gas and oil boilers always lose energy from the primary fuel, because some of it goes up the flue during combustion – so they’ll never be 100% efficient. In contrast, air source heat pumps typically attain efficiency levels of 300% or more.
This is because they take one unit of electrical energy to harvest heat from the outdoor air, and upgrade this to produce three units of warmth to power your central heating and hot water.
ASHPs have been installed in tens of thousands of UK homes, ranging from self-builds through to listed buildings and community heating schemes. So there’s a heat pump to work with almost any property or project.
Planning a new build where the space heating and hot water loads are different? We offer a model specifically designed for this purpose.
Or maybe you have an existing boiler and don’t want to replace it yet: if you add a heat pump to create a hybrid system, you can still earn payments from the Renewable Heat Incentive (RHI; see the ‘what will it cost?’ section below for more details).
Want wifi operation? Modern ASHPs come with advanced, internet-based controls as standard, allowing you full control and reporting wherever you are in the world.
New products are helping to give maximum flexibility to homeowners, too. For instance, Mitsubishi Electric’s 8.5kW Ultra Quiet Ecodan virtually eliminates the need to seek planning permission.
The heat pump’s low-noise design means that it will almost always qualify as permitted development (which sets a limit of 42dB on sound pressure levels 1m away from a neighbour’s nearest door or window).
The right output will depend on how you intend to use it. For an average three-bed house that has modern standards of insulation and glazing, something like an 8.5kW ASHP will suffice. That’s the size I use in my 1950s home in Herts.
There are also smaller models designed specifically for new houses (which are built to good fabric efficiency standards) and larger versions that can work together to supply reliable heating for larger or older properties.
Mitsubishi Electric’s website has an online Ecodan selector tool that gives a quick indication of efficiencies, cost savings and the type of heat pump suited to almost any UK home.
It depends on your property’s makeup and which other parts of the system you need to replace, such as radiators, the cylinder etc. Upfront figures range from £3,000 to £10,000 for a typical home.
Much of this will be offset by the RHI, where the government makes quarterly payments to you for seven years. If you take a Metering and Monitoring Service Package (MMSP) you could receive an additional £1,610 over the course of the RHI. Add this to savings in gas/oil bills, and the payback period to recoup your investment can be surprisingly quick.
Max Halliwell is product manager for renewable heating at Mitsubishi Electric. He has been involved in the renewables sector since the early adoption of air source heat pumps. For more advice and information visit ecodan.co.uk