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Need heating restored quickly?
Heat pump installations typically take
4–8 weeks from survey to completion — an MCS installer won't rush a system that will be in your home for 20 years. If it's cold now, a temporary plug-in electric heater (£40–80 from any DIY retailer) is the sensible bridge while you make the right long-term decision.
Use our free calculator to get an estimate today.
Your boiler has stopped working. You're being quoted £2,500–£4,500 for a replacement gas boiler — but you've also heard there's a £7,500 government grant available for heat pumps. So which do you do?
The net cost gap is much smaller than most people expect. The real question isn't the upfront cost — it's whether your home and situation are right for a heat pump right now. Below are the four things that actually determine the answer.
The four questions that actually matter
1
Does your home have loft insulation and double glazing?
Heat pumps work most efficiently in homes that hold heat well. They deliver warmth at lower temperatures than gas boilers, so the better your insulation, the more comfortable and cheaper to run your system will be.
✓ Good to go: Loft insulated to 100mm or more, double or triple glazed throughout. EPC rating C or D is typically fine.
⚠ Worth checking first: Pre-1919 solid-wall properties with no external or internal insulation. A heat pump will work, but adding wall insulation first meaningfully reduces running costs and required pump size.
2
Is there outdoor space for an external unit?
An air source heat pump needs an outdoor unit — roughly the size of a large suitcase — mounted on a wall bracket or sitting on the ground. It needs to be accessible and at least one metre from any boundary.
✓ Good to go: Most gardens, side returns, rear yards, or even a front driveway work well. Permitted development rights apply to most homes.
⚠ Trickier: Upper-floor flats without private outdoor space, or listed buildings. Both have solutions (communal installs, listed building consent) but need more planning time.
3
Are you replacing a gas boiler, oil boiler, or electric heating?
The £7,500 Boiler Upgrade Scheme grant is available to almost any home replacing a fossil fuel or electric heating system in England or Wales. Your MCS-certified installer applies on your behalf and deducts the grant from your invoice before you pay.
✓ Grant eligible: Gas boiler, oil boiler, LPG system, electric storage heaters, or electric room heaters. Scheme runs until 2028 — no immediate rush, but no reason to delay.
⚠ Not eligible: Replacing an existing heat pump or a biomass boiler. New-build properties also don't qualify.
4
Do you plan to stay in the property for at least 5 years?
Heat pumps make the strongest financial sense over a 10–20 year horizon. Running costs are broadly comparable to gas on a standard tariff today, and improving as electricity decarbonises. Properties with EPC A or B ratings and low-carbon heating are also increasingly valued by buyers.
✓ Staying put: Clear case for a heat pump. Lower carbon, long lifespan, future-proofed against rising gas prices and potential carbon taxes.
⚠ Moving within 2 years: A heat pump still adds value to your property — but a quick boiler replacement may be simpler if you're mid-sale or exchanged.
The real upfront costs in 2026
Here's what you're actually comparing — including the government grant already deducted:
New gas boiler
£2,000–£4,500
Installed, including controls and labour. A like-for-like Worcester Bosch or Vaillant combi replacement is typically at the lower end.
⚠ Gas boilers banned in new builds from 2025. Regulatory risk on gas infrastructure is increasing.
Air source heat pump
£3,500–£6,500
Net cost after £7,500 BUS grant. Gross cost typically £11,000–£14,000. Includes heat pump unit, hot water cylinder, installation and commissioning.
✓ £7,500 government grant until 2028
Real-world data point: The median installed cost of an air source heat pump through the Boiler Upgrade Scheme in 2025 was £13,002 according to Ofgem statistics. After the £7,500 grant, that's £5,502 — comparable to a premium boiler replacement, but with 20+ years of low-carbon heating ahead of it and no dependence on gas prices.
Running costs: it's all about the tariff
This is where most comparisons mislead people. At the standard electricity price cap (24.7p/kWh), a heat pump costs slightly more to run than gas. But dedicated heat pump electricity tariffs change this picture significantly — and every major energy supplier now offers one.
| Electricity scenario |
Effective rate |
Typical annual HP cost |
vs gas (~£800–950/yr) |
| Standard tariff (Ofgem cap) |
24.7p/kWh |
~£1,100–1,400/yr |
£200–500 more |
| ⭐ Dedicated HP tariff (Cosy Octopus / EDF) |
~17p blended |
~£750–950/yr |
Broadly equal |
| Optimised + solar or battery storage |
~13p blended |
~£550–700/yr |
Save £200–400/yr |
Cosy Octopus gives you 8 hours of cheap electricity daily (currently ~14.5p/kWh) timed around your heat pump's heating schedule, with a standard day rate for the rest of the time. EDF Heat Pump Tracker applies a flat 10p/kWh discount during 6 hours a day with no peak penalty — better for homes that can't easily avoid the early evening period. Both are available to any home with a heat pump — you don't have to be an existing customer to switch.
The bottom line: nobody with a heat pump should be on a standard electricity tariff. Switching to a dedicated tariff is the single biggest lever on your annual running costs, and it costs nothing to do.
Do you need to replace your radiators?
The most common anxiety about heat pumps is the idea that every radiator in the house needs replacing. In practice, this is far less common than people fear.
Heat pumps operate at lower flow temperatures (45–50°C) than gas boilers (70–80°C), so each radiator delivers slightly less heat. But if your home loses heat slowly — as most well-insulated post-1980s properties do — your existing radiators are usually adequate at those lower temperatures.
A real-world example from the same property we used to calibrate our calculator: a 4-bedroom detached house in West Yorkshire, surveyed by an MCS-certified installer in February 2026, required zero radiator replacements. All 13 existing radiators were retained. The installer selected a 9kW unit with a 300L hot water cylinder — total installed cost before grant approximately £12,500.
Your installer will assess this as part of a free, no-obligation heat loss survey. Our calculator includes a radiator upgrade toggle so you can model both scenarios before you speak to anyone.
When replacing the boiler makes more sense right now
Your home is poorly insulated and you can't fix that yet
A heat pump in a leaky home will run hard, cost more, and disappoint you. The right sequence is insulate first (loft, then cavity walls), then install the heat pump. A well-sized heat pump in a well-insulated home is transformative. The same pump in a draughty 1930s terrace is an exercise in frustration.
You need heating restored in the next two weeks
A thorough MCS-compliant installation takes 4–8 weeks from initial survey to completion. No reputable installer will shortcut a heat loss survey or rush the commissioning. If you're genuinely cold now, a temporary fix — repairing the boiler if possible, or plug-in electric heaters — buys you the time to plan the heat pump properly rather than under pressure.
You're mid-sale and exchanging contracts within weeks
If you're actively selling with completion imminent, a boiler repair or cheap replacement is the practical call. Don't start a 6-week heat pump installation mid-transaction. Plan the heat pump for your next property — or factor it into the sale price.
The honest position on running costs: At today's tariffs, heat pumps on a standard electricity rate cost slightly more to run than gas. On a dedicated heat pump tariff they're broadly equal. With solar or battery storage, they're cheaper. The financial case strengthens every year as electricity decarbonises and gas prices trend upward. The environmental case is already clear: a heat pump produces around 75% less carbon than a gas boiler on today's UK grid mix — and that figure keeps improving.
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Takes 3 minutes. Uses your EPC data automatically. No name, email, or phone number required — ever.
✓ EPC auto-populated from postcode
✓ BUS grant applied automatically
✓ Three tariff scenarios compared
✓ MCS installer referrals included
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Frequently asked questions
Can I get a heat pump installed quickly if my boiler has broken?
Typically 4–8 weeks from survey to installation for a standard retrofit. Some larger installers offer faster surveys, but the full installation — heat loss survey, equipment ordering, installation day, commissioning and handover — takes time to do properly. If you need heating now, use plug-in electric panel heaters as a bridge. They're cheap to buy and cost around £0.25/hour to run.
Will I definitely get the £7,500 BUS grant?
The Boiler Upgrade Scheme grant is available to most owner-occupiers and private landlords in England and Wales replacing a fossil fuel or electric heating system. You need a valid EPC and an MCS-certified installer. Your installer applies for the grant and deducts it from your invoice — you never handle the money. The scheme budget has been topped up and runs until 2028, so it isn't about to run out for typical applicants.
Do I need to upgrade my radiators?
Possibly not. Many homes built since the 1980s with modern radiators run heat pumps efficiently at 45–50°C flow temperature without any changes. Your MCS installer will do a room-by-room heat loss assessment and tell you exactly which rooms, if any, need larger radiators. In well-insulated homes this is often zero. Our calculator includes an optional radiator upgrade cost so you can see both scenarios before speaking to anyone.
What happens to my hot water?
Unlike a combi boiler, a heat pump heats water in a cylinder — typically 200–300 litres for a 3–4 bedroom home. The cylinder heats up during cheap-rate electricity periods (overnight or daytime off-peak) and stores hot water for use throughout the day. Most heat pump owners report better hot water pressure and consistency than with a combi. If you currently have a combi with no cylinder, you'll need space for one — usually an airing cupboard or utility room works.
Will a heat pump keep my home warm in cold weather?
Yes. Modern air source heat pumps operate efficiently down to −15°C to −20°C. The UK rarely sees temperatures below −5°C for extended periods. During the January 2025 cold snap, 86% of UK heat pump owners reported their system kept them warm throughout. The key is correct sizing — which is exactly what the MCS heat loss survey determines.
Is my home suitable for a heat pump?
Around 90% of UK homes are suitable. The main requirements are: some outdoor space for the external unit (roughly 1m × 1m, wall-mounted or ground level), an EPC of D or above (or willingness to improve insulation first), and a property that isn't an upper-floor flat without private outdoor space. Victorian solid-wall properties can work very well but benefit from insulation improvements first. Run our free calculator for a property-specific estimate.