I’ve teamed up with James Stalker to bring you some fresh content on heat pumps in older homes. I previously owned a 1960s property and always assumed it wasn’t suitable for this kind of upgrade. But having seen the work James has done across Devon, that assumption doesn’t hold up. He’s a NAPIT MCS heat pump assessor who deals with older, harder-to-heat homes every week. What follows is his take on what actually changes when you swap an oil boiler for a heat pump, and it’s a good read for anyone who’s written their own house off in the same way I did.
Here’s James’s story.
Half the houses I work in still have an oil tank round the back. I install air source heat pumps across Devon, and a good chunk of that work is in older cottages and farmhouses, the kind of place where someone checks the tank level with a torch every few weeks in January. Most of those homeowners assume a heat pump won’t cope. I’ve heard “my house is too old for one” more times than I can count, usually from someone told exactly that by an installer who didn’t want to do the sums.
Here’s what genuinely changes when you take an oil boiler out and put a heat pump in, because most of what gets written about this online is either sales copy or scare stories, and neither is much use standing in your hallway wondering what to do next.
The House Doesn’t Need to be Perfect First
This is the biggest misconception I run into. People think their solid walls, single-glazed windows or lack of loft insulation rule them out. It doesn’t. Whatever heating system you have, gas, oil or heat pump, your house loses heat at the same rate. Insulation helps any system run more efficiently, but a heat pump doesn’t need a super-insulated new-build shell to work. What it needs is a system designed around your actual heat loss, room by room, rather than a boiler swapped like-for-like and hoped for the best.
That’s the bit a lot of oil-to-heat-pump jobs get wrong. A heat pump runs at a lower flow temperature than an oil boiler, somewhere around 45-50°C rather than the 70-80°C an old boiler pushes out. Run the same radiators at that lower temperature without checking they’re up to it, and some rooms will feel cooler than they used to. Do the heat loss survey first and you find out exactly which radiators need upsizing and which are already fine. On a lot of jobs it’s a handful, not a full house re-plumb.
A Recent One: Zeal Monachorum, near Crediton
I took a call from a family whose oil boiler had just died. No heating, no hot water, and the obvious quick fix was another oil boiler. They asked whether a heat pump could go in instead without months of delay.
We did the free assessment, ran the heat loss calculations within the week, sorted the Boiler Upgrade Scheme paperwork, and had the whole job, an Ideal Logic Air 8kW with a new 250-litre heat-pump cylinder, in and commissioned just over three weeks after the first phone call. The grant came off the quote upfront, so they never had to find that money and claim it back. All the outdoor pipework went into insulated trunking to hold up against the weather.
The end cost, after the grant, came out comparable to a like-for-like oil boiler replacement. That surprises people every time. They expect a heat pump to be the expensive option, and with the grant applied that gap mostly disappears.
What People Actually Ask Me Before They Commit
Will it cost more to run than oil? Usually less, but that depends on your electricity tariff and on the system being designed properly. A well-designed heat pump gives you three to four units of heat for every unit of electricity it draws, against about 85% efficiency from an oil boiler. Do I need to rip out all my radiators? Only the ones the heat loss survey flags, and on plenty of jobs that’s one or two, not the lot. Are they noisy? Genuinely not. You won’t hear it unless you’re stood right in front of the outdoor unit, and we run a sound calculation as part of the MCS requirements so neighbours aren’t affected either.
The one I take most seriously is hot water. People worry a heat pump cylinder won’t keep up with a family bathroom routine. Every install gets a new heat-pump-specific cylinder, better insulated, bigger coil, set to stay topped up rather than heating from cold each time, so hot water is there when it’s wanted rather than rationed.
The Grant, in Plain Terms
If you’re currently on oil or LPG, the Boiler Upgrade Scheme gives £7,500 towards an air source heat pump, plus a £1,500 uplift for moving off oil or LPG rather than gas, so £9,000 in total. That’s available until March 2027. We claim it on the homeowner’s behalf and take it straight off the quote, so nobody has to find that money upfront and wait for it back. We handle the application as part of the job, and I’ve set out how the higher oil and LPG figure gets applied in practice if you want the worked example.
If you’re weighing this up for your own oil-heated house, the age or construction of the building rarely rules it out. What matters is whether the survey and the system design are done properly. Read more on how an oil-to-heat-pump swap works in an older Devon house.
James Stalker runs Eco Pro Renewables, installing air source heat pumps across East Devon. He’s also a freelance NAPIT MCS assessor, auditing other installers’ work. Eco Pro Renewables, Exmouth.
