Heat Pumps
MCS-certified air source heat pumps for low-carbon, lower-cost heating
The government pays the first £7,500, VAT is zero until 31 March 2027, and the grant application is ours to handle. What you save depends on what you are replacing — we tell you which before you buy, not after.
See How It Works
How the system works, and what it does to your money.
*Illustrative guide figures while launch pricing is finalised — your exact numbers follow the free survey.
What We Do
A heat pump replaces your gas or oil boiler with a clean, highly efficient system that draws warmth from the outside air — delivering about three units of heat for every unit of electricity it uses. As an MCS-certified installer, OKPW designs and fits air source heat pumps in-house, from a proper room-by-room heat-loss survey through to commissioning and aftercare. Because we are a design & build company, we can upgrade radiators, fit underfloor heating, improve insulation and integrate the system into a wider renovation — all under one roof. We also handle your Boiler Upgrade Scheme grant application, currently worth up to £7,500 off the cost of an air-source heat pump where eligible.
What It Is For — and What It Is Not
An air source heat pump does two jobs: it heats your rooms and it heats your water. It is not an air conditioner. Knowing the difference before you enquire saves everybody a wasted visit.
Right for your house if…
- You are replacing a gas, oil or LPG boiler — a heat pump does exactly the same two jobs, heating and hot water.
- You are off the gas grid on oil or LPG. The savings are real — £290 to £780 a year — and the grant rises to £9,000 until 31 March 2027.
- You are on electric heating or storage heaters. Energy Saving Trust puts that saving at £800 to £1,200 a year.
- You have somewhere outside for a unit around 1000mm × 800mm, with clear air around it.
- You have room for a hot water cylinder — an airing cupboard, roughly 600mm × 800mm of floor.
- You are renovating anyway, so floors, pipework and radiators are already coming up.
Not what you want if…
- You want cooling. A heat pump heats. Cooling is a different machine — an air-to-air unit, which is what air conditioning is.
- You want hot water from an air conditioning unit. Air-to-air heats the air in a room; it cannot fill a bath.
- You want to keep the gas boiler as well. A grant-funded heat pump has to fully replace the old system, and hybrids are not eligible.
- There is genuinely nowhere for a cylinder. A hybrid can still work technically, but it forfeits the £7,500.
- The house is listed, or the only sensible position fronts a highway in a conservation area. Both need consent before anything is ordered.
- You have a modern, efficient gas boiler, you want a smaller bill, and you will not change tariff. On Energy Saving Trust's July 2026 modelling that household ends up about £110 a year worse off.
If what you actually want is cooling in summer, say so and we will quote air conditioning instead — a different machine and a different conversation. We would rather lose the heat pump job than fit you the wrong one.
Key Benefits
- About three units of heat for every unit of electricity — 2.8 was the measured median across the UK’s largest field trial
- Up to £7,500 off through the Boiler Upgrade Scheme, handled by us
- MCS-certified installs that protect warranties and grant eligibility
- Cuts your home’s carbon footprint and future-proofs your heating
Our Process
Home Survey
A full room-by-room heat-loss calculation to size the system correctly — no guesswork, no oversizing. We assess your insulation, emitters and hot-water needs.
System Design
An MCS-compliant design specifying the heat pump, cylinder, radiator or underfloor upgrades and controls, with a clear estimate of running costs and savings.
Grants & Paperwork
We apply for the Boiler Upgrade Scheme grant on your behalf and handle all MCS and DNO notifications so you don't have to.
Installation
Our in-house team installs the heat pump, cylinder, pipework and any emitter upgrades with minimal disruption, keeping your heating running wherever possible.
Commissioning
The system is balanced, weather-compensation set, and performance verified. You receive your MCS certificate and a tailored guide to running it efficiently.
Aftercare
Annual service plans and responsive support keep your system efficient and your warranty valid for years to come.
What's Included
- Room-by-room heat-loss survey
- MCS-compliant system design
- Air source heat pump
- Hot-water cylinder & buffer (as required)
- Radiator or underfloor heating upgrades
- Smart heating controls & weather compensation
- Boiler Upgrade Scheme grant application
- MCS & DNO notifications
- Commissioning & MCS certificate
- Manufacturer warranty registration
- Aftercare & service plans
What You Need to Know Before You Buy
None of this is in the brochure. All of it comes up on site, so here it is first.
It needs a hot water cylinder
There is no combi equivalent. MCS sizes hot water at 45 litres per bedroom plus one, which puts most three and four bed homes on a 200–250 litre cylinder taking roughly 600mm × 800mm of floor. Your existing cylinder almost always has to go — its internal coil is too small to take heat at heat pump temperatures.
It runs cooler, for longer
A boiler pushes water round at 70–80°C in bursts. A heat pump runs at 30–45°C almost continuously. That is where the efficiency comes from: across UK field data the median was 3.50 at a 35°C flow temperature and 2.38 at 55°C. It is also why the house feels steadily warm rather than hot-then-cold.
Some radiators will need to be bigger
Radiator outputs are published at a 50°C difference between water and room. At heat pump temperatures the same radiator gives roughly half that, so it typically needs to be about twice the size. We measure every room rather than guessing, and you get the list of which ones change before you sign anything.
What the efficiency figure really means
The SCOP on the box is calculated for the climate of Strasbourg. In the UK's largest field trial the median was 2.80 — about three units of heat for every unit of electricity — while well-optimised systems metered independently reached a median of 3.92. Nine installations in ten came in below their design figure, so treat any quoted SCOP as a target, not a promise.
It works in the cold
The system is sized to meet all of your heat loss at about −1.7°C in London, with no electric back-up doing the work. Efficiency does fall — a median of 2.44 at −6°C — and in cold damp weather it runs a defrost cycle, which costs 2–3% of output over a year. A properly designed system holds temperature through it.
Planning is usually not needed — but the rules are specific
In England a heat pump is normally permitted development: no minimum distance to the boundary since 29 May 2025, a unit no bigger than 1.5 cubic metres, two pumps on a detached house and one on anything else, and never on a pitched roof. Listed buildings need consent. Conservation areas restrict where it can go rather than whether you can have one.
The noise calculation is compulsory
Every domestic installation in England needs an MCS 020 sound calculation showing 37 dB(A) or less, measured one metre from the nearest window of a neighbour's habitable room. It is the only accepted method since May 2026. We do the calculation, keep it on file, and give you a copy.
Your electricity supply gets notified
A heat pump is electrical demand, so your network operator is notified within 28 days of installation — or applied to beforehand if your supply is already tight. That is the installer's job, not yours, and it is included.
The grant, as it stands today
£7,500 off an air source heat pump in England and Wales, or £9,000 if you are off the gas grid replacing oil or LPG, until 31 March 2027. Since 28 April 2026 you no longer need an EPC to apply and outstanding insulation recommendations no longer block it. The scheme now runs to 2030. We apply on your behalf; you confirm consent.
VAT is 0% until 31 March 2027
After that it returns to 5%. The zero rate applies because we install it — buying the equipment on its own is standard-rated at 20%. It is separate from the grant, so you get it either way.
Your EPC might not go up
Today's band is a fuel-cost sum calculated on 2012 gas and electricity prices, so it does not reward a heat pump the way you would expect. Government's own EPC consultation says installing one 'could reduce the EER'. We give your assessor the make, model, MCS certificate and design flow temperature so the system is scored on its real performance rather than the poor default that causes most of the drops — and EPCs are being rebuilt for 2027 with a separate heating-system score.
Against mains gas, the saving comes from the tariff
A heat pump tariff is worth up to £330 a year, and without one, swapping a modern gas boiler lands close to break-even. Tariffs are commercial products, not guarantees — OVO closed its heat pump tariff to new customers in February 2026. The pump lasts fifteen years or more; the tariff might not. We would rather you heard that from us than found out in year two.
Figures correct at 10 August 2026, from Ofgem, HMRC, MCS, the Planning Portal and Energy Saving Trust's July 2026 modelling. Your own numbers come from the free survey.
Why Choose OKPW
MCS Certified
Fully MCS-certified installs — the standard required for grant eligibility, warranties and peace of mind.
£7,500 Grant Handled
We manage your Boiler Upgrade Scheme application end to end, so the grant comes straight off your price.
Design & Build Advantage
Emitter upgrades, insulation and the wider renovation handled by one team — not three contractors blaming each other.
Common Questions
Will a heat pump keep my home warm in winter?
Yes — a correctly sized, MCS-designed system runs efficiently even in cold weather. We size it from a full room-by-room heat-loss survey, never a guess.
Do I need new radiators?
Sometimes. Heat pumps run at lower flow temperatures, so we check your emitters and upgrade radiators or add underfloor heating where needed.
How much is the grant?
The Boiler Upgrade Scheme currently offers up to £7,500 off an air-source heat pump for eligible homes. We handle the whole application for you.
Find Out What It Would Save You
A free, no-obligation survey by the people who do the work — covering Putney, Wandsworth, Richmond, Kingston, Streatham and Lewisham.
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