Heating a Devon Holiday Let: Boiler, Heat Pump or Electric, and What Actually Suits Intermittent Occupancy
Devon has one of the largest concentrations of holiday accommodation in England, with tens of thousands of self-catering properties across the county and occupancy that swings from near-100% in August to well under 30% in February. That pattern breaks most of the assumptions heating systems are designed around. A family home is occupied every evening and heated to a predictable routine. A holiday let sits at 8°C for four days, then has six people arrive at 4pm on a Friday expecting hot showers within the hour, and a thermostat that will be pushed to 25°C and left there because nobody is paying the bill. Choose the system for a normal house and you get either huge standing costs or cold guests and a bad review. Here's what actually works, and what each option costs across a Devon letting year.
Why Intermittent Occupancy Changes the Answer
The core issue is response time versus standing loss, and the two pull in opposite directions.
A gas or oil boiler has a high output relative to the building - often 24kW to 30kW - so it can lift a cold cottage from 8°C to 20°C in two to three hours. A heat pump is sized to the building's heat loss, typically 6kW to 12kW for a Devon cottage, and is designed to run steadily rather than in bursts. From cold, that same cottage might take six to ten hours to come up to temperature.
For a normal home, the heat pump's approach is more efficient. For a let with a 4pm changeover, it means the property has to be brought up to temperature before the guests arrive, which in turn means heating an empty building.
The practical numbers for a three-bedroom Devon cottage, roughly 110 square metres with reasonable insulation:
- Full heat-up from cold (8°C to 20°C) - boiler 2 to 3 hours, heat pump 6 to 10 hours
- Cost of that single heat-up - roughly £4 to £7 on gas, £7 to £11 on oil, £6 to £9 on a heat pump at typical 2026 unit rates
- Holding at 12°C between bookings rather than letting it drop - £1.80 to £3.50 a day, and it cuts the heat-up time roughly in half
- Annual heating spend across a typical letting year - £900 to £1,600 depending on system, occupancy and how disciplined the controls are
That "hold at 12°C" line is the single most useful lever available, and it favours heat pumps considerably. A heat pump maintaining a low background temperature continuously is working in exactly the conditions it is efficient in. A heat pump asked to do repeated cold starts is not.
Which System Suits Which Devon Property
Devon's letting stock is unusually varied, and the answer genuinely differs by property type. If you want a straight answer for a specific building rather than a general one, a heat loss assessment on the property itself is what settles it, because the fabric matters more than the postcode.
On-gas properties in Exeter, Exmouth, Plymouth and the larger towns. A modern condensing combi is still the pragmatic choice for a let, particularly for smaller properties. High output, instant hot water, no cylinder to legionella-manage, and low capital cost at £2,200 to £3,500 fitted. The counter-argument is that gas is a shrinking long-term proposition and it does nothing for your EPC beyond the baseline.
Off-gas cottages in the villages, Dartmoor fringe and South Hams. This is where oil currently dominates and where heat pumps make the strongest case. Oil at 2026 prices runs the property at a meaningfully higher cost per kWh delivered than a well-designed heat pump, and oil tanks in holiday lets bring their own problems - theft, a delivery you have to be present for, and a bunded tank replacement bill of £1,800 to £3,000 when it fails.
Solid-wall and cob properties , of which Devon has a great many. Heat pumps work in these, but only after the fabric is addressed. A cob cottage with single glazing and no loft insulation will need a large, expensive unit and will still be costly to run. Fabric first is not a slogan here, it is the difference between a system that works and one that does not.
Very small units - shepherd's huts, annexes, single-bedroom conversions. Direct electric with good controls, or a small air-to-air unit, often beats anything wet. The capital cost of a wet system cannot be justified across 500 square feet.
What the Grant Position Means for Letting Property
This is where holiday let owners get caught out. Grant eligibility for heat pumps is not automatic just because the property is residential. We've set out the current position in our guide to boiler and heat pump grants available to Devon homeowners in 2026, and the key point for lettings is that the Boiler Upgrade Scheme is available for both domestic and small non-domestic properties in England and Wales, but the property must have a valid EPC and the application is made by an MCS-certified installer on your behalf, not by you. If the property is run as a furnished holiday let, get the eligibility confirmed in writing before you commit to a quote.
Hot Water Is the Real Problem, Not Space Heating
Guest complaints about heating are overwhelmingly about hot water, not room temperature. Six people wanting showers between 7am and 9am is a demand profile no domestic system was designed for.
The options and their honest limits:
- Combi boiler. Unlimited hot water but only one outlet at a time at useful flow. Two simultaneous showers on a 30kW combi means both are weak. Fine for a two-bedroom let, marginal for a four-bedroom one.
- Unvented cylinder, 210 to 300 litres. The right answer for most multi-bedroom lets. A 250-litre cylinder delivers roughly four to five consecutive showers before needing reheat. £1,800 to £3,200 installed, and it works equally well on a boiler or a heat pump.
- Heat pump with a correctly sized cylinder. Works well, but the cylinder needs to be larger than a boiler equivalent because the reheat is slower - budget one size up, and set the reheat to complete overnight on a cheap tariff.
- Electric showers. Genuinely useful as a second bathroom solution in a let. 10.5kW gives a modest but reliable flow completely independent of the main system, so a cylinder running dry does not end in a complaint.
Legionella is a legal duty, not an optional extra. Any property let to the public with a stored hot water system needs a written risk assessment and a routine. Practically: store at 60°C, distribute above 50°C, flush all outlets after any void period over a week, and keep a log. Heat pumps run lower flow temperatures than boilers, so a heat pump cylinder needs either a weekly immersion-driven pasteurisation cycle or a high-temperature cycle from the unit itself. This is straightforward to set up and a genuine liability if ignored.
Controls: Where Most of the Money Is Won or Lost
This matters more in a let than the choice of heat source, and it is by far the cheapest intervention.
A holiday let needs controls that a guest cannot defeat and an owner can manage remotely:
- Remote-access smart thermostat with a lockable or limited setpoint range. £180 to £400 fitted. Lets you pre-heat from your phone before a changeover and drop the property back afterwards without a visit.
- Upper temperature limit , typically capped at 21°C or 22°C. Guests who cannot set 26°C will not set 26°C, and most never notice the cap.
- Window-open detection or thermostatic radiator valves in every room. Guests open windows with the heating on constantly; TRVs at least stop the whole system chasing one cold room.
- Occupancy-linked scheduling tied to your booking calendar rather than a fixed weekly programme, so an empty February week costs almost nothing.
- Frost protection set to 7°C minimum , non-defeatable, because a burst pipe in an unoccupied Devon cottage in January is a five-figure problem and an insurance argument.
A realistic figure: good controls on an otherwise unchanged system typically cut a holiday let's heating bill by 15% to 30%. On a £1,400 annual spend that is £210 to £420 a year for a one-off £300 outlay.
Devon's Climate, and What It Means for Sizing
Devon's heating requirements are milder than most of the UK, and that genuinely helps heat pumps here.
The county's design outside temperature is around -1°C to -2°C in most locations, against -3°C to -5°C for much of the Midlands and North. Coastal Devon - Exmouth, Dawlish, Teignmouth, Plymouth - rarely drops below freezing for sustained periods, which means a heat pump spends almost all its year in the temperature band where it performs best, delivering seasonal efficiency around 3.2 to 3.8 in a well-designed system.
Two local caveats that do bite:
Dartmoor and the higher ground are a different proposition entirely. Properties above roughly 250m see design temperatures several degrees lower, far more wind exposure, and a heating season that runs a month longer at each end. Size accordingly and do not use a coastal figure for a moorland cottage.
Salt air on the coast. Heat pump units within a few hundred metres of the sea need corrosion-resistant coatings on the coil and casing, and an annual rinse-down as part of servicing. Skipping this shortens unit life materially. Most manufacturers offer a coastal specification, and it is worth specifying rather than assuming.
Devon's rainfall - 1,000mm to over 2,000mm a year depending on elevation - matters less for the heat pump itself than for siting. Keep the unit off a surface that floods, and keep the condensate drain clear, because a frozen or blocked condensate line in a January cold snap is one of the most common call-outs.
Running Costs Compared Across a Devon Letting Year
Working example: three-bedroom cottage, 110 square metres, reasonable insulation, 55% annual occupancy, held at 12°C between bookings.
- Oil boiler - annual heating and hot water around £1,250 to £1,650. Plus tank maintenance and the risk of running dry mid-booking.
- Mains gas condensing combi - around £950 to £1,300. Cheapest to run where gas is available, cheapest to install, worst long-term trajectory.
- Air source heat pump, well designed, standard tariff - around £1,100 to £1,500.
- Air source heat pump on a heat-pump-specific tariff with overnight cylinder reheat - around £750 to £1,100. This is where the economics genuinely win.
- Direct electric throughout - £1,900 to £2,800. Only sensible in very small units.
Capital costs for context: gas combi £2,200 to £3,500; oil boiler replacement £3,500 to £5,500; air source heat pump £9,000 to £16,000 before grant support, which the Boiler Upgrade Scheme can reduce substantially where the property qualifies.
The other number worth having in view is EPC. Holiday lets let as furnished holiday accommodation sit outside the domestic Minimum Energy Efficiency Standard that applies to assured shorthold tenancies, but a poor rating still affects mortgageability, resale and increasingly the booking platforms' own filters. Moving a Devon cottage off oil and onto a heat pump commonly shifts an EPC by one to two bands.
Frequently Asked Questions
Do heat pumps work in holiday lets that sit empty for days?
Yes, but the control strategy has to change. Rather than letting the property go cold and reheating from scratch, hold it at a low background temperature - around 12°C - between bookings and pre-heat from your phone a few hours before arrival. Run that way, a heat pump suits a let well. Asked to do repeated cold starts, it will disappoint.
Is a holiday let eligible for the Boiler Upgrade Scheme?
The scheme covers domestic and small non-domestic properties in England and Wales, and the property needs a valid EPC. Because furnished holiday lets can fall either side of that line depending on how the property is used and rated, get eligibility confirmed in writing by your MCS-certified installer before committing, as the application is made by them rather than by you.
How do I stop guests running the heating at 25°C?
Fit a smart thermostat with a capped maximum setpoint, usually 21°C or 22°C, plus thermostatic radiator valves in every room. Guests almost never notice the cap. Combined with occupancy-linked scheduling, good controls typically cut a let's heating bill by 15% to 30%.
What size hot water cylinder does a holiday let need?
For a three or four bedroom let, a 250 to 300 litre unvented cylinder is usually right - around four to five consecutive showers before reheat. On a heat pump, go one size larger than you would on a boiler, because the reheat is slower, and schedule it overnight.
Do I need a legionella risk assessment for a holiday let?
Yes. Any property let to the public with a stored hot water system needs a written risk assessment and a documented routine: store at 60°C, distribute above 50°C, flush all outlets after void periods over a week, and keep a log. Heat pump systems need a weekly high-temperature or immersion pasteurisation cycle because they run lower flow temperatures.
```json { "@context": "https://schema.org", "@type": "FAQPage", "mainEntity": [ { "@type": "Question", "name": "Do heat pumps work in holiday lets that sit empty for days?", "acceptedAnswer": { "@type": "Answer", "text": "Yes, but the control strategy has to change. Rather than letting the property go cold and reheating from scratch, hold it at a low background temperature of around 12C between bookings and pre-heat remotely a few hours before arrival. Run that way, a heat pump suits a let well. Asked to do repeated cold starts, it will disappoint." } }, { "@type": "Question", "name": "Is a holiday let eligible for the Boiler Upgrade Scheme?", "acceptedAnswer": { "@type": "Answer", "text": "The scheme covers domestic and small non-domestic properties in England and Wales, and the property needs a valid EPC. Because furnished holiday lets can fall either side of that line depending on how the property is used and rated, get eligibility confirmed in writing by your MCS-certified installer before committing, as the application is made by them rather than by you." } }, { "@type": "Question", "name": "How do I stop guests running the heating at 25C?", "acceptedAnswer": { "@type": "Answer", "text": "Fit a smart thermostat with a capped maximum setpoint, usually 21C or 22C, plus thermostatic radiator valves in every room. Guests almost never notice the cap. Combined with occupancy-linked scheduling, good controls typically cut a let's heating bill by 15% to 30%." } }, { "@type": "Question", "name": "What size hot water cylinder does a holiday let need?", "acceptedAnswer": { "@type": "Answer", "text": "For a three or four bedroom let, a 250 to 300 litre unvented cylinder is usually right, giving around four to five consecutive showers before reheat. On a heat pump, go one size larger than you would on a boiler because the reheat is slower, and schedule it overnight." } }, { "@type": "Question", "name": "Do I need a legionella risk assessment for a holiday let?", "acceptedAnswer": { "@type": "Answer", "text": "Yes. Any property let to the public with a stored hot water system needs a written risk assessment and a documented routine: store at 60C, distribute above 50C, flush all outlets after void periods over a week, and keep a log. Heat pump systems need a weekly high-temperature or immersion pasteurisation cycle because they run lower flow temperatures." } } ] } ```
```json { "@context": "https://schema.org", "@type": "Article", "headline": "Heating a Devon Holiday Let: Boiler, Heat Pump or Electric, and What Actually Suits Intermittent Occupancy", "description": "Holiday lets heat differently to homes - empty for days, then full for a weekend, with guests who never touch a thermostat. Here's which heating system actually works for a Devon holiday let, what each costs to run, and the EPC and safety rules that apply to lettings.", "author": { "@type": "Organization", "name": "The Team" }, "datePublished": "2026-09-22", "dateModified": "2026-09-22", "articleSection": "Heating" } ```
You might also like
