Grant Aerona3 vs Mitsubishi Ecodan

Which Is Better: Grant Aerona3 or Mitsubishi Ecodan?

Neither is better by default; the decision depends on whether you want Grant’s established Aerona3 range or Mitsubishi’s newer R290 Ecodan positioning. According to Grant UK’s Aerona3 brochure, the range offers outputs from 4kW to 17kW with SCOP values from 3.29 to 3.72, while Mitsubishi Electric UK (2026) says Ecodan R290 can reach 75°C and operate down to -25°C. See also: BUS Grant 2026 guide.

For most homeowners, that means you are comparing two credible but differently framed retrofit routes. Grant reads more like a mainstream domestic R32 platform, while Mitsubishi is now presenting a stronger R290, high-temperature message. For context, read our complete guide to heat pumps in the UK, best heat pump brands guide, and heat pump running costs article. If your property is eligible, our BUS grant survey page is the route for domestic ASHP applications, subject to eligibility.

What Are the Main Technical Differences?

The main differences are refrigerant, temperature positioning, and how confidently each product is presented for retrofit. According to Grant UK’s Aerona3 brochure, Aerona3 uses R32 and quotes SCOP up to 3.72 across the range, while Mitsubishi Electric UK (2026) says Ecodan R290 uses refrigerant with GWP 3 and offers high water temperatures up to 75°C.

The broad technical comparison looks like this:

Prices and services correct at time of writing — always request a current quote.

Those figures should not be treated as a one-line winner because they come from different product families and test conditions. The practical message is that Grant offers a broad domestic range, while Mitsubishi is pushing a more explicit R290 and retrofit-friendly story.

That difference matters most where the house is not an easy low-temperature fit. In more straightforward homes, installer quality will usually matter more than the product narrative.

Which One Usually Fits Retrofit Better?

For retrofit, Mitsubishi often appeals more where the homeowner wants R290 and stronger boiler-replacement reassurance, while Grant often appeals where a simpler mainstream route is sufficient. According to Energy Saving Trust (2026), heat pumps still perform best with suitable emitters, controls, and insulation, so no brochure removes the need for proper design work.

Grant can be a sensible answer where the project is straightforward and the installer is comfortable showing how the numbers work without leaning on high-temperature reassurance. Mitsubishi can be attractive where the property sits closer to the edge of easy retrofit and the homeowner values the stronger R290 and temperature narrative. Neither route should bypass heat-loss calculations, radiator checks, or realistic hot-water design.

Typical retrofit decision points include:

1. how much emitter upgrade is likely
2. what domestic hot-water performance the house needs
3. whether low GWP refrigerant is a priority
4. which installer can explain the full system credibly

What Do Installers and Homeowners Most Often Get Wrong?

The most common mistake is assuming that Mitsubishi’s hotter R290 positioning makes Grant a weaker option in every retrofit. According to MCS (2025), system performance still depends on design, commissioning, and handover quality, so a well-designed Grant installation can easily outperform a badly designed Mitsubishi one.

Another mistake is assuming broad product range automatically means easier retrofit. Range breadth helps with selection, but it does not prove radiator suitability, hot-water performance, or day-to-day efficiency. Those answers come from design discipline, not from catalogue size.

Typical comparison mistakes include:

• choosing on refrigerant alone
• over-valuing maximum temperature claims
• ignoring the installer’s real product experience
• comparing brand stories before comparing whole-system design

What Does This Mean in London, Surrey, and TW Homes?

In London, Surrey, and TW homes, the better choice between Grant Aerona3 and Mitsubishi Ecodan usually depends more on the house and installer than on headline marketing. According to Ofgem (April 2026), electricity remains 24.5p/kWh on the typical direct-debit cap, so design quality, controls, and commissioning still have a material effect on bills.

For the South East housing stock Electromatic typically surveys, the useful question is whether the installer can demonstrate a credible low-temperature design route first. Some homes will justify Mitsubishi’s R290 positioning. Others will fit perfectly well within a Grant design if the radiators, controls, and hot-water setup are handled properly.

That is why local survey data matters more than brand confidence. Our heat pump size calculator guide, heat pump installation process article, and heat pump cost UK guide help make that comparison more practical.

It also helps separate homes that genuinely need stronger retrofit reassurance from homes that simply need cleaner design and commissioning. That distinction often changes whether Mitsubishi’s R290 positioning is worth paying extra for.

How Electromatic Can Help

If you are comparing Grant Aerona3 vs Mitsubishi Ecodan, the next step is a survey that checks heat loss, emitters, hot water, and controls together before the brand choice is locked in. According to MCS (2025), compliant heat pump performance depends on documented design and commissioning, so the engineering route matters more than the catalogue result.

Electromatic can show where each route makes practical sense for a London or Surrey retrofit and whether the wider project should include solar panels or battery storage planning at the same time. We work under MCS certification via our accredited umbrella partner, and where the installation is eligible we can handle BUS grant applications for air source heat pumps, subject to eligibility. We can also coordinate ASHP and solar through one contractor.

That gives you a property-specific recommendation rather than a generic “brand winner”. It also makes quote comparison easier because the scope is clearer.

It also means radiator upgrades, hot-water expectations, and control strategy are tested before the product choice is frozen. In practice, that is often where Grant becomes the more proportionate answer or where Mitsubishi proves its stronger retrofit case.

That disciplined sequence protects you from buying on anxiety alone. It also gives you a clearer route if the wider plan includes solar, battery storage, or staged electrical upgrades later.

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Call us: 07718 059 284 | Email: admin@electromatic.uk

Frequently Asked Questions

Most follow-up questions on Grant Aerona3 vs Mitsubishi Ecodan are really about whether R290 and higher published temperatures make Mitsubishi the clear retrofit winner. According to current manufacturer positioning and MCS principles, the real answer remains property-specific because design and commissioning still decide results.

How much does refrigerant choice matter in this comparison?

It matters if low GWP and future-facing refrigerant strategy are priorities for you. It still does not replace the need for proper heat-loss calculations and emitter design.

Can Grant Aerona3 still work well in retrofit homes?

Yes. In many homes it can be a sensible fit if the system is designed properly and the installer is not trying to force the property into an unsuitable low-cost shortcut.

Do I need Mitsubishi Ecodan because it reaches 75°C?

Not necessarily. The better question is what flow temperature your property actually needs to heat efficiently in normal use.

Is Mitsubishi Ecodan always the stronger option in older homes?

No. It may be attractive in some older properties, but older homes still need proper design and do not become simple just because the brochure is more retrofit-oriented.

Which option makes more sense in Surrey and TW homes?

The better option is whichever system your installer can justify most clearly for your property. In South East retrofit work, good survey evidence matters more than badge preference.

The information in this article is for general guidance only and does not constitute financial, legal, or technical advice. Energy savings estimates are based on typical UK household data from the Energy Saving Trust and Ofgem (April 2026 price cap). Actual savings depend on your property type, insulation levels, energy usage patterns, and electricity tariff. The Boiler Upgrade Scheme (BUS) grant of £7,500 is subject to eligibility criteria set by Ofgem — not all properties qualify. Electromatic M&E Ltd operates under MCS certification via an accredited umbrella partner. All installations comply with Building Regulations Part L and MCS standards. E&OE.

Written by Electromatic M&E Ltd — ASHP & Solar installer, London & Surrey (electromatic.uk)

Last updated: April 2026 | Electromatic M&E Ltd, Company No. 13837345