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Replacing an oil boiler with a heat pump in Devon takes about a week, and the design work done before that week decides how well it turns out. If your boiler is getting on and the tank in the garden is one winter fill away from testing your patience, you will have heard both versions: the neighbour who swears by theirs, and the story in the paper about someone shivering through February. What separates the two is usually that design work, far more often than the house.
Key Takeaways
- Replacing an oil boiler with a heat pump takes about a week: old boiler out, oil line capped, outdoor unit and heat-pump cylinder in.
- Off-gas-grid oil and LPG homes can claim a £9,000 Boiler Upgrade Scheme grant, deducted from the quote upfront, on applications made up to 31 March 2027.
- Around 41,000 Devon households heat with oil, and none of them are protected by the energy price cap.
- Radiators mostly stay put; a room-by-room heat loss survey picks out the few that need upsizing for 45 to 50°C flow temperatures.
- Savings against oil depend on your electricity tariff; the dependable wins are steady bills, no deliveries and no tank to watch.
This guide covers what the swap involves for a Devon property: what gets removed, what goes in, what happens to your radiators and your old tank, what it costs to run, and how the grant works. It is written from the experience of James Stalker, who runs Eco Pro Renewables in Exmouth, an MCS-certified installation company, and who audits other installers’ heat pump work for a living as a NAPIT MCS assessor.
What Physically Changes When You Convert from Oil to a Heat Pump
The swap is more contained than you might expect. Your oil boiler comes out, the oil line to the tank in the garden is disconnected and capped, and two new items go in: an air source heat pump outside and a hot water cylinder inside. Everything else in the wet central heating system stays.
What the swap involves
The oil system
- The oil boiler
- The oil feed from the tank
The tank itself stays where it is unless you choose removal.
Two new items
- An air source heat pump outside, 4 to 10 kW for most East Devon properties
- A heat-pump cylinder inside, often where the old boiler or cylinder lived
Joined to the house by pipework through the wall.
Your heating system
- The radiators, apart from any the survey flags
- The pipework and the wet central heating system itself
Reused wherever the design allows.
The outdoor unit sits on a ground base or wall brackets, usually against a side or rear wall, with clear airflow around it (how quiet it runs is a fair next question). Ideal’s Logic Air range is what we install most often, paired with a pre-plumbed cylinder whose filter, diverter valve, cylinder stat and overheat stat arrive already fitted, which shortens the install and removes a whole category of on-site wiring mistakes.
The cylinder has a larger coil than the one it replaces, so it reheats efficiently at lower temperatures and holds a full day’s hot water. Our air source heat pump installation service covers the whole conversion, from heat loss calculation through to commissioning and handover.
Will You Need New Radiators?
Probably fewer than you fear. A heat pump runs your heating at a flow temperature of 45 to 50°C, against the 70°C plus an oil boiler throws out, so each radiator needs enough surface area to deliver the same heat at a gentler temperature. Plenty of radiators in 1960s to 1990s Devon houses were generously sized when they were fitted and cope fine.
The room-by-room heat loss survey settles it for each room, and a typical oil boiler to heat pump conversion here might see two or three radiators swapped and the rest untouched.
How the survey decides each radiator
Every room measured
We calculate the heat loss of each room in the house.
Checked against its radiator
That figure is set against the radiator serving the room.
Only the short ones upsized
Radiators that fall short get upsized, and the rest stay on the wall.
Anyone who quotes you a full radiator replacement without measuring a single room is guessing, and you would be paying for the guess.
The Week-Long Installation, Day by Day
A standard oil boiler replacement in Devon runs Monday to Friday, and the work arrives in a fixed order.
The week, Monday to Friday
Old boiler out, outdoor unit in
- The old boiler comes out, and the system is drained and flushed
- The outdoor unit goes onto its base
Cylinder and pipework
- The cylinder goes in and the pipework is connected
- Any radiators flagged by the survey are swapped
Wiring and commissioning
- The electrical team completes the wiring, usually within the day
- Commissioning begins
Commissioned and handed over
- The system is commissioned, balanced and handed over
- A proper walkthrough of the controls before anyone leaves
Eco Pro runs one or two jobs at a time with the owner involved on site, so the person who designed your system is the same person answering questions about it on Thursday.
What Happens to the Old Oil Tank
Once the heat pump is commissioned, the tank is redundant, so run it down over your final months on oil rather than filling it in autumn out of habit.
What happens to the tank
Capped and left in place
- Oil line disconnected
- Line capped
- Tank left safely where it stands
Usable oil still has value: local distributors and some removal companies will transfer or buy it back.
Removed for good
- Drained and cleaned
- Taken away
- Legally disposed of
Plastic tanks usually leave in sections, and steel ones are generally cut up on site.
Households who choose removal are often surprised by how much garden they get back: a typical domestic tank with its required clearances takes up a serious corner of a plot. Taking it away also ends the running worries that came with it.
The worries that leave with the tank
- Leaks
- Condensation in the fuel
- Sludge in the feed
- The gauge you check every cold snap
Heat Pump vs Oil Boiler Running Costs: The Honest Answer
41,000
Heating oil sits outside the energy price cap, so every one of those homes carries the full swing of the market each winter. Devon has one of the largest concentrations of oil-heated homes in Britain.
The honest answer on savings
Against oil at current prices, on a standard electricity tariff, the running cost saving from a heat pump is modest. Anyone promising your bills will halve is selling, not advising.
1 unit of electricity
3 to 4 units of heat
A well-designed system delivers roughly three to four units of heat for every unit of electricity it uses, and that efficiency keeps the comparison close despite electricity’s higher unit price.
What changes decisively is the shape of the cost. Off-grid households on oil pay for deliveries and tank upkeep on top of the fuel, while a heat pump runs on electricity bought on a capped, predictable tariff, cheaper again on a dedicated heat-pump tariff for the hours the system runs.
What you are buying is a predictable bill from a system with no tank to watch and no delivery to chase. Good design keeps it that way, which is why we also service and tune heat pumps, including systems other companies installed.
The £9,000 Grant: Timing Matters for Oil and LPG Homes
The Boiler Upgrade Scheme gives eligible owner-occupiers in England and Wales £7,500 towards an air source heat pump, rising to £9,000 for off-gas-grid homes replacing oil or LPG heating. As an MCS-certified installation company, Eco Pro makes the application for you and deducts the grant from your quote upfront.
£9,000
Deducted from your quote upfront, so you never pay it out and claim it back.
Applications up to 31 March 2027£7,500
For other eligible owner-occupiers in England and Wales.
0%
Heat pump installations are zero-rated until 31 March 2027.
Eligibility criteria apply. Scheme terms move, so re-check the figures before you commit.
The higher rate closes to new applications on 31 March 2027. For oil and LPG households the sensible sequence is to have the assessment and survey done now, and the application submitted well before that date.
“Your House Isn’t Suitable”: Older Devon Properties
Plenty of East Devon homeowners have been told a heat pump will not work in their property. Stone and cob buildings around Ottery St Mary, Woodbury and Newton Poppleford do lose more heat than a modern estate house, and heat loss is exactly what the survey measures and the design compensates for.
- Too old
- Walls too solid
- Too draughty
- What size
- What flow temperature
- Which emitters
Two changes have made older properties easier candidates.
No EPC needed to apply
A valid EPC is no longer strictly required to apply for the grant, and other evidence is accepted instead. That unblocks period homes whose certificates are out of date or missing altogether.
Since April 2026The cause of poor results
When a heat pump underperforms in an old house, the documented cause is nearly always an oversized unit or skipped design work. An oversized unit cycles on and off, wears early and wastes electricity.
Oversizing and skipped designAs a NAPIT MCS assessor, James audits other installers’ heat pump work across the region, so he has seen where those installations go wrong, and it is rarely the house.
Frequently Asked Questions
About a week. A typical Eco Pro installation in Devon starts on a Monday and is commissioned by Thursday or Friday, including taking out the old boiler. Removing the oil tank is an optional extra; otherwise we cap the oil line and leave the tank safely in place.
Book my free home assessmentNot if you want the grant. The Boiler Upgrade Scheme requires the heat pump to fully replace the fossil fuel system. A correctly sized heat pump does not need a backup, even in a cold Devon January.
Book my free home assessmentDetached houses and bungalows in East Devon usually fall between 4 and 10 kW. The room-by-room heat loss survey gives the exact figure, and a quote produced without one is a guess.
Book my free home assessmentYes. Modern units hold their output well below freezing and are the standard form of heating in far colder countries such as Norway. Devon’s mild coastal climate is easy territory by comparison.
Book my free home assessment£7,500 as standard, or £9,000 for off-gas-grid oil and LPG homes in England and Wales, on applications made up to 31 March 2027. For Devon homeowners, Eco Pro applies on your behalf and deducts it from the quote upfront. Correct as of 4 October 2026.
Book my free home assessmentGet Clarity on Your Own Property
You do not need to decide anything today. The useful first step is finding out what your house needs: James visits, looks at the property, talks through the options and gives you a free estimate on the spot. If the numbers make sense, the room-by-room heat loss survey follows at £250 plus VAT, waived in full when you go ahead, with a fixed quote within 24 hours.
Book my free home assessmentPrefer to talk it through first? Ring 01395 202030. James answers, and he is the person who will price the job.
★★★★★
“The heat pump is almost silent, which was something we were worried about, and the results have been fantastic. We’re lovely and warm and always have plenty of hot water.”
Grace Murphy · Google review
