Mitsubishi Ecodan Heat Pumps in the UK

The 5kW Ecodan R290 outdoor unit, PUZ-WZ50VAA, costs £2,596.60 including VAT at City Plumbing and £4,524.00 including VAT at Saturn Sales, both checked on 9 October 2026 for the same model code. That £1,927 spread on an identical box is the first thing worth knowing about Ecodan pricing. The second is stranger: on the one figure that decides where the unit can legally stand in your garden, the 8.5kW Ecodan is quieter than the 5kW. Mitsubishi's own datasheets give the PUZ-WZ85 a sound power level of 54 dB(A) and the PUZ-WZ50 56 dB(A), and the planning calculation written into English law runs on that number alone. Every figure below comes from Mitsubishi Electric's UK datasheets, its published warranty terms, UK merchant listings or gov.uk, read on 9 October 2026.

Which R290 Ecodan sizes does Mitsubishi sell in the UK?

Mitsubishi lists five R290 Ecodan sizes on its UK product page. They are 5, 6, 8.5, 10 and 12kW, sold as PUZ-WZ50VAA, PUZ-WZ60VAA, PUZ-WZ85V/YAA, PUZ-WZ100V/YAA and PUZ-WZ120V/YAA, with product information sheets covering all five. A sixth code, the 8kW PUZ-WZ80VAA, has its own Mitsubishi product information sheet circulating through UK merchants but has dropped off that page, so if a quote names it, ask your installer to send that datasheet. Read the two digits after WZ as a rough size marker, not a measured output: Mitsubishi rates the WZ85 at 8.5kW and the WZ100 at 10.0kW, but the WZ120 at 11.5kW and the WZ80 at 8.2kW, under the heating condition it publishes, which is an outdoor temperature of minus 7°C with 35°C flow.

Three parts of the code do real work on a quote. V is single phase and Y is three phase, an option Mitsubishi offers only on the 85, 100 and 120. A BS suffix is the coastal unit, built for salt-laden air and priced above the standard version. And WZ is the propane range while WM is the older R32 range, which is still on merchants' shelves in 5, 6, 8.5 and 11.2kW sizes as PUZ-WM50VHA, WM60VAA, WM85VAA and WM112VAA.

All six R290 units share a maximum leaving water temperature of 75°C and an operating range from minus 25°C to plus 46°C ambient. A 75°C flow is what makes a radiator retrofit plausible without replacing every radiator in a 1930s semi, though running at 75°C is also what wrecks the efficiency, so treat it as a cold-snap capability and not a design condition. The decision it actually bears on is whether your existing radiators are big enough, which we go through in our guide to choosing heat pump kit.

What an Ecodan costs at UK merchants today

These are equipment prices including VAT, read off UK merchant listings on 9 October 2026. They are not installed prices, and the gap between the two is most of the job.

Two things in that table are worth more than the individual numbers.

The first is the spread. The same PUZ-WZ50VAA is £2,596.60 at one UK merchant and £4,524.00 at another on the same day, and both list their prices as including VAT. Neither is a rogue listing. It means a quote that itemises the heat pump at a figure near the top of that range is not necessarily padded and a quote near the bottom is not necessarily a bargain, so the useful question is what the installer actually paid plus what they charge to fit it, not whether the box price looks right.

The second is that propane is not the expensive option here. The R290 5kW at £2,596.60 undercuts the R32 6kW at £2,950.72 at the same merchant, which is the reverse of the pattern on Samsung's UK range, where the current R290 units carry about a thousand pounds of premium over the older R32 ones. If an installer tells you the newer refrigerant costs more, ask to see the two line items.

One caution before you compare any of those figures with an installer's quote. A merchant selling you a boxed heat pump is making a supply-only sale, and HMRC's Notice 708/6 is explicit that "if you supply energy-saving materials without installing them your supply will be standard-rated", so the prices above carry 20% VAT. The same unit supplied and fitted is zero-rated: the notice says "a zero rate applies to the installation of certain specified energy-saving materials from 1 May 2023 to 31 March 2027", and "from 1 April 2027 onwards these will revert to the reduced rate of VAT of 5%". An installer's price is therefore not the merchant price plus labour. The identical logic applies to solar, and we unpick it in our guide to VAT on solar panels.

For what the whole job costs rather than the box, start with our UK heat pump cost guide, which works from installed prices and the grant. Which rung of the range your home lands on is a separate question, and our guide to heat pump sizing covers the calculation that settles it.

A bigger Ecodan can stand closer to your neighbour's window than a smaller one

Mitsubishi publishes A-weighted sound power levels of 56, 56, 58, 54, 55 and 55 dB(A) for the 5, 6, 8, 8.5, 10 and 12kW R290 units, tested to BS EN 12102, and those are the numbers a permitted development noise calculation runs on. Read that list again: the 8.5kW is the quietest unit in the range and the 8kW is the loudest, so stepping up a size can buy you clearance rather than cost you it.

England's permitted development right for a domestic air source heat pump requires the calculation in MCS 020 a) Issue 1.1, dated 14 April 2025, which article 6 of SI 2025/560 wrote into Part 14 of the 2015 Order with effect from 29 May 2025. Step 8 of that standard asks whether the calculated sound pressure level at every assessment position is "equal to or lower than 37.0 dB(A)". Its definitions put the assessment position at "a position 1m external to the centre point of any door or window to a habitable room of a neighbouring property as measured perpendicular to the plane of the door or window", and a habitable room is any room used for sleeping or living, excluding bathrooms, toilets, corridors and laundry rooms. There is no site-boundary test in the current standard, whatever you may be told. Step 7's formula is L_p = L_w + 10 log (Q / 4πr²) − A_B, where Q is the directivity factor, r is the distance in metres and A_B is any barrier attenuation.

Run Mitsubishi's own sound power figures through it for the commonest siting in a British garden, a unit on the ground against one house wall with clear line of sight to the neighbour's window, and you get this:

If you would rather check that arithmetic than take it on trust, the standard's own worked example does it for a 60 dB(A) unit on a house in Chester. At 8 metres with a 5 dB partial-view barrier it prints 31.96 dB(A), and at 5 metres with a 10 dB full barrier it prints 31.04 dB(A). The figures above are produced by the same formula, which reproduces both of those to within 0.01 dB.

Two details move those distances more than the model choice does.

The directivity factor punishes tight siting. The standard sets Q2 for a unit with one reflecting surface, Q4 for two and Q8 for three, where a reflecting surface is any surface within 1 metre of the unit, including the ground but explicitly not vegetation, and it has to extend at least 1 metre beyond the edge of the unit in two or more directions. A unit on the ground against one house wall is therefore Q4, which is what the table assumes. Tuck the same 8kW into a corner between two walls and it becomes Q8, which pushes the required distance from 6.3 metres to 9.0. A heat pump with more than three reflective surfaces, the lightwell case, cannot meet MCS 020 a) at all.

A wall helps enormously and a hedge does not. The barrier matrix allows a 10 dB reduction for a solid brick or masonry wall, or a solid fence at least 18mm thick, that completely obscures the view of the assessment position from the top edge of the unit. A thinner solid fence gets 5 dB. Partial line of sight halves the allowance. Open fences, fences with gaps, walls in poor repair and vegetation all count as zero.

Now the figure you will actually be shown. Every one of the six R290 Ecodan units is listed at 40 dB(A) sound pressure at 1 metre, identical from the 5kW to the 12kW, and that number is no use for siting. Sound pressure and sound power are different quantities, step 3 of the standard asks for sound power, and a brochure figure that does not change across a range cannot be telling you anything about where a given unit can stand. Mitsubishi also holds Quiet Mark certification for the R290 range, which Quiet Mark awards without publishing a decibel level at all. If an installer hands you a noise assessment built on 40 dB(A), it is the wrong figure, and the assessment is wrong with it. The same pattern of a flattering headline number sitting next to a harder datasheet number shows up across Daikin's UK range too.

Permitted development rules differ in Wales, Scotland and Northern Ireland, so none of the above transfers across the border unchanged.

Mitsubishi publishes the SCOP for every model, at both flow temperatures

Mitsubishi's UK datasheets give an MCS SCOP at 35°C and a second one at 55°C for all six R290 units, which is the comparison most manufacturers leave you to guess at. SCOP is the seasonal figure that predicts a winter's electricity bill. A single COP reading is one operating point.

The shape of that table is the argument for getting your flow temperature designed properly rather than inherited from the old boiler. The 12kW unit returns 4.71 at 35°C and 3.51 at 55°C, so the same machine in the same house loses about a quarter of its seasonal efficiency if the system is designed to run hot. Across a 12,000 kWh heating demand that is the difference between roughly 2,550 kWh and roughly 3,420 kWh of electricity a year, and at any tariff you care to use it dwarfs the gap between the best and worst model in the range.

Ask for the SCOP at the design flow temperature on your own room-by-room heat loss survey, in writing. It is a reasonable request and Mitsubishi has published the numbers to answer it, which is more than can be said for every brand. Samsung publishes a SCOP for one of its four UK sizes and leaves the other three blank, as we found going through its EHS Mono R290 spec tables.

Mitsubishi also rates all six units A+ for water heating, with a water heating efficiency between 129% and 143% depending on the model, quoted in combination with its EHPT20X-MEHEW cylinder.

The 12kW on single phase wants a 40 amp breaker

Mitsubishi lists the single-phase PUZ-WZ120 at a maximum running current of 35 A with a recommended MCB of 40 A, against 13 A and 16 A for the 5 and 6kW units. On a house with a 60 A or 80 A main fuse, an electric shower and an EV on the drive, that is a real constraint rather than a footnote, and it is worth raising before the survey rather than after it.

Three phase drops every one of the larger units to 12 A, which is why a three-phase supply changes the conversation about a big Ecodan in a large house. Almost no British home has one, so for most readers the single-phase column is the real one.

On size, the 5, 6 and 8kW units are 1050 mm wide, 480 deep and 1020 high. The 8.5, 10 and 12kW units are the same footprint at 1040 high. Flow rates run from 14 litres per minute on the 5kW to 34 on the 10 and 12kW, which is why the bigger units step up from 22 mm to 28 mm pipework: a 12kW Ecodan plumbed in 22 mm because that is what was already there will not deliver its rated output.

Refrigerant charge is 0.6 kg on the 5, 6 and 8.5kW units, 0.82 kg on the 10 and 12kW and 1.0 kg on the 8kW. Mitsubishi states the GWP of R290 as 0.02 on these datasheets, citing IPCC 6th edition values, and separately lists R32 at 675 under the earlier basis used by Regulation (EU) No 517/2014. The practical point is not the number but the chemistry: R290 is propane, classed A3 flammable, so every manufacturer specifies an ignition-source exclusion zone around the unit. Ask where that zone falls on your wall before the installer picks the spot, because it rules out positions next to an air brick, a boiler flue or an outside socket.

Your Ecodan warranty depends on your installer's Mitsubishi status

Mitsubishi links the length of an Ecodan warranty to the trade status of the installer who fits it, so the same unit can come with a different warranty period depending on who installs it. Mitsubishi sets the periods for each installer tier, and for the cylinder and ancillaries, in its own installer warranty terms, which can change. Check the current terms with your installer and get the period for your outdoor unit and your cylinder written into the quote.

Read the conditions before you sign, because the ones that cost money are easy to miss.

• The longer warranty is linked to your installer. Because the period depends on the installer's status, ask what happens to your warranty if the firm that fitted your heat pump later leaves Mitsubishi's partner programme, and get the answer in writing.
• Register it within 3 months. Mitsubishi's homeowner guarantee page says accepted claims "are dependent on if the products have been registered within 3 months of them being installed", and that "the length of guarantee depends on what Ecodan product is registered". Register on the day the system is commissioned.
• Ask what labour is covered. Ask your installer what Mitsubishi's current terms pay towards labour on a warranty repair, and what is excluded, before you sign.
• Report faults quickly. Mitsubishi sets time limits and conditions on warranty claims, so check the current terms with your installer and report a fault in writing the week it happens.

Servicing matters too. The same Mitsubishi page says "an Ecodan service is due every year to maintain your warranty". Skip services and keep no paperwork and you have handed the manufacturer a reason to decline. Vaillant and Daikin attach comparable conditions to their own tiered terms, so this is the category norm rather than a Mitsubishi quirk, and we cover how those compare on the heat pump kit pillar.

So the question to ask before you sign is not "how long is the warranty". It is which Mitsubishi tier this installer holds today, what warranty period that gives you, and whether they will put their Mitsubishi partner status in the quote.

Boiler Upgrade Scheme eligibility, and the MCS check you cannot do yourself

An Ecodan air-to-water heat pump qualifies for the £7,500 Boiler Upgrade Scheme grant in England and Wales, provided both the installer and the specific product are MCS certified. Gov.uk's current figures, read on 9 October 2026, are "£7,500 towards an air source heat pump", "£7,500 towards a ground source heat pump (including water source heat pumps and those on shared ground loops)", "£5,000 towards a biomass boiler" and "£2,500 towards an air-to-air heat pump". There is an uplift on top: "Until March 2027, you can get an additional £1,500 towards an air source heat pump or ground source heat pump" where the property is heated by oil or LPG and has no mains gas connection.

Gov.uk publishes no closing date for the scheme itself, so be wary of a quote that implies it is about to end. The only published deadline is the March 2027 expiry of that £1,500 uplift. Scotland runs its own Home Energy Scotland grant and loan instead, and gov.uk states the Northern Ireland scheme is closed.

The grant runs off the MCS register rather than the brand, which is why the model code matters. Here is the honest position on checking it yourself, because it is not good. Searching the MCS product directory for "Ecodan" on 9 October 2026 returns 48 rows, every one of them a legacy PUHZ, QUHZ, CAHV or CRHV code, and every certification period on them ended on or before 20 June 2025. Not one current PUZ-WZ or PUZ-WM code appears, and that is because the directory's keyword search matches the product name field and not the model number: a search for "PUZ-W" returns nothing at all, and so does a search for "Mitsubishi Electric". Two of those 48 Ecodan rows are even filed with the description "Monocrystalline Module", which tells you something about the state of the data.

Treat all of that as the directory's limitation and not as evidence about any product. What it means practically is that you cannot verify a current Ecodan's MCS listing yourself, so ask the installer for the MCS certificate reference for your exact outdoor unit and cylinder pairing, and for their own MCS number, because the Boiler Upgrade Scheme application needs both. The installer applies on your behalf and the grant comes off what you pay.

What to ask for on an Ecodan quote

Five things, and a good installer hands all five over without being chased.

• The full model code, including the V or Y and any BS suffix, so you know whether you are being quoted single or three phase and whether you are paying the coastal premium without living near the coast.
• The sound power level for that code, and the MCS 020 a) calculation showing the distance to the nearest neighbouring habitable window, the Q value used, and any barrier allowance shown as a separate line. If the assessment quotes 40 dB(A), it is using the wrong figure.
• The SCOP at your design flow temperature, taken from your own room-by-room heat loss survey, not the 35°C column.
• The installer's Mitsubishi tier, written into the quote, since that is what sets your warranty period, plus confirmation of who registers the Homeowner Guarantee Card and when.
• The electrical check: the MCB size the unit needs, your main fuse rating, and whether the DNO has to be notified.

On the money side, the thing that catches people out is not the heat pump. It is the cylinder, the controls, the pipework upgrades and the radiator changes, which is where the difference between a £9,000 job and a £15,000 job usually lives. Our heat pump cost guide breaks that down line by line.

Frequently asked questions