We all know that heat pumps offer a cleaner, greener solution to the traditional gas boiler, and as such are our government-mandated future. They’re key to reducing the staggering 15 per cent of the UK’s total emissions that currently come from heating homes. We also know we’re going to have to make the switch at some point, the only question being: when?
The summer months are generally mooted as the ideal, but also, “you might say that the best time is when the government has just released details of a new grant,” says Ian Mather, National Business Development Manager for energy supplier British Gas (it has, and it’s worth £7,500 for both air source and ground source heat pumps, and British Gas will help you with the paperwork, if needed). Add the fact that gas prices have recently risen significantly and there’s a triumvirate of excellent reasons all pointing to now being the moment. But what do we need to know first? And what exactly does the process entail?
How do heat pumps work?
Very simply, a heat pump is an electrical boiler in two parts, with one part outside your property, and another inside, probably in a cupboard, “like a traditional airing cupboard,” says Ian. It runs off mains supply but can also use your solar panels (if you have them) or wind turbine, with mains back-up. “It’s classed as renewable because you are getting out more than you put in. A heat pump is a minimum of 350 per cent efficient, i.e. for every 1kw you put in, you’re getting 3.5kw out – the other 2.5kw is captured from the air, the ground, or water – depending on what sort of heat pump you have got.”
Air source, ground source, water source: Is there a ‘best’ heat pump?
There are no hard and fast rules as to which type will best suit which property. Most rare is the water-source heat pump, though Ian knows of one fitted one in a house that had a sufficiently deep moat. A ground-source heat pump is connected to a ground loop, but it is what Ian might advise for a block of flats. “You could install a multiple ground array, also known as a shared ground array, and you wouldn’t have units outside.” An air-source heat pump is visible, lives outside, “usually to the rear of a property, and is mounted on anti-vibration feet on a secure base”. If you want to hide it, a heat pump cannot be placed in a specially designed pagoda – “They have mandatory clearances to ensure efficient air flow,” explains Ian – which some potential purchasers might find off-putting, but worth knowing is that a lot of manufacturers can wrap your heat-pump so it matches your exterior wall, making it less visible. Finally, there’s an exhaust air heat pump, which Ian explains “is typically only used in a new build, as it forms part of the home’s ventilation system.”
In terms of brands, “each one has got different features and benefits,” says Ian. “Mainly, heat pumps are made either by boiler manufacturers who have moved into heat pumps, or by air-conditioning manufacturers, because a heat pump is essentially the same, but runs the other way around,” says Ian. (You can, incidentally, get heat pumps that both heat and cool, according to need. “They tend not to be eligible for government grants though,” says Ian. “They’re seen as more of a luxury.”)
Prices vary, depending on type of heat pump, size of house (and thus size of heat pump needed), and so on. It’s impossible to ballpark, but Ian hazards “anywhere from £5,000, including the grant.”
How do you know if you can have one?
“The only true way to tell is to get a survey,” says Ian, though an up-to-date Energy Performance Certificate (EPG) will also be needed. While theoretically any property can be made suitable, the truth is that, unless you have been thorough in terms of insulation, a period property probably isn’t ready. My Victorian terrace, for instance, which has got double glazing and loft insulation, would still need to have the walls insulated (which we should have done when we first moved in. Now, I’m loathe to redecorate). The key is to ensure that installing a heat pump would be cost-effective. “There are some properties where a heat pump would not yet work as well as a gas boiler,” points out Ian. “But certainly we can advise on the changes that would need to be made.” The survey, incidentally, is free.
“We would then do a heat loss calculation to work out how large the heat pump needs to be, we’ll look at location options and discuss them with you, along with necessary piping, and check that you’re happy with the aesthetics of it all,” continues Ian. “And we’d check radiator sizing, discuss radiator positioning, assess underfloor heating, and carry out an electrical survey to check that the heat pump can be attached.” Heat pump radiators tend to be larger than gas boiler-fed radiators, either in height, width or depth – the temperature is lower but the surface area is higher. It’s another unattractive-sounding element, “but you could split them up and have, say, three smaller discreetly-placed radiators, rather than one big one,” suggests Ian.
Installing heat pumps
There’s more than one heat pump supplier and fitter and your energy company ought to be able to advise you; Octopus Energy, for instance, has its own engineers who are currently installing in London and the home counties, and EDF will recommend a trusted installer. In terms of British Gas’s timeframe, “depending on the complexity of the property, the survey would probably be done in a single visit,” confirms Ian. Actual installation can take anything from two-and-a-half days to longer, depending on size of the house; Buckingham Palace is a greater commitment than a two-bedroom bungalow. That’s why it’s a good idea to have it done over the summer, when you don’t need the heating on.
Typically, scaffolding would not be needed as the pipework is done internally (thus preserving more energy); floorboards would be put back, along with carpeting, “though if you’ve just had a new wall-to-wall carpet put down we’d recommend getting a professional carpet-fitter as the carpets won’t yet have reached their full stretch,” says Ian. And because the new radiators are probably bigger, you won’t have to redecorate behind them.
All that’s left is to dispose of the old boiler, which a good installer can do for you (including British Gas), break it down and recycle it – another win for the environment.
