Mitsubishi Ecodan vs Grant Aerona3

Which Is Better: Mitsubishi Ecodan or Grant Aerona3?

Neither is better for every property; the right choice depends on whether Mitsubishi’s newer R290 Ecodan route or Grant’s mainstream Aerona3 platform fits the retrofit better. According to Mitsubishi Electric, Ecodan R290 can deliver up to 75°C water temperature and guaranteed operation down to -25°C, while Grant says Aerona3 R32 covers outputs from 6kW to 17kW. See also: BUS Grant 2026 guide.

For most homeowners, that means this is a comparison between two different retrofit philosophies rather than between a good and bad product. Mitsubishi often looks stronger where high-temperature R290 reassurance matters. Grant often looks stronger where a simpler mainstream domestic route and wider output choices feel more relevant. 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 each route presents retrofit confidence. According to Mitsubishi Electric, current Ecodan R290 models use refrigerant with GWP 3, reach up to 75°C, and operate down to -25°C, while Grant says Aerona3 uses R32 and offers 6kW, 10kW, 13kW, and 17kW models.

The practical comparison looks like this:

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

That means Mitsubishi often looks more future-facing on paper, particularly where refrigerant choice and 75°C messaging matter to the buyer. Grant often looks more straightforward where the homeowner wants a simple domestic heating proposition. In practice, the better answer still depends on heat loss, emitters, hot water, and how confident the installer is with the platform.

Which One Usually Fits Retrofit Better?

For retrofit, Mitsubishi often feels stronger where the house is more challenging or the owner wants stronger high-temperature reassurance, while Grant often fits straightforward domestic replacements well. According to Energy Saving Trust (2026), heat pumps still perform best with suitable emitters, controls, and insulation, regardless of brochure claims.

Mitsubishi can be attractive where the installer wants to lean on R290 positioning, lower GWP, and higher-water-temperature capability. Grant can be very practical where the house fits a mainstream domestic replacement story and the quote needs to stay simple and legible. In both cases, the real decision still comes down to whether the system is being sized honestly and whether the radiators and cylinder support the design properly. That matters more than whether the brochure sounds more advanced.

Typical retrofit decision points include:

1. whether the property needs stronger high-temperature reassurance
2. whether a mainstream domestic output spread better suits the house
3. how comfortable the installer is with Mitsubishi or Grant controls
4. whether the quote clearly explains hot water and emitters

What Do Homeowners Most Often Get Wrong?

The most common mistake is assuming that Mitsubishi’s R290 and 75°C headline automatically make Grant the weaker choice. According to MCS (2025), actual performance depends on design, commissioning, and handover quality, so a well-designed Grant route can outperform a badly delivered Ecodan route.

Another mistake is focusing on refrigerant alone. Refrigerant matters for product direction and environmental profile, but it does not replace radiator checks, pipework suitability, cylinder sizing, or weather-compensated controls. Buyers also sometimes assume a more mainstream product must be technically inferior. In practice, a mainstream domestic route can be exactly what a straightforward South East home needs if the installer can explain it clearly and commission it properly.

Typical comparison mistakes include:

• choosing on refrigerant alone
• treating 75°C as proof of better retrofit fit
• overlooking the installer’s platform experience
• ignoring optimisation after the first heating season

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

In London, Surrey, and TW homes, the better choice between Mitsubishi Ecodan and Grant Aerona3 usually depends more on the survey and installer than on the brand. According to Ofgem (April 2026), electricity is 24.5p/kWh on the typical direct-debit cap, so controls, emitters, and hot-water settings still affect real bills materially.

For many ordinary South East homes, Grant often makes sense where the project is a straightforward domestic retrofit with clear sizing bands. Mitsubishi often becomes more attractive where the house is larger, the owner values lower-GWP refrigerant, or the installer can defend the higher-temperature R290 route properly. The better answer is the one supported by heat-loss numbers and room-by-room design, not by online reputation alone.

That is especially true once emitter upgrades and hot-water demand are written into the scope. Those practical items usually decide value more clearly than brand prestige.

That is why local design work matters more than generic brand hierarchy. Our heat pump size calculator guide, heat pump installation process article, and heat pump cost UK guide help make this a practical comparison.

How Electromatic Can Help

If you are comparing Mitsubishi Ecodan vs Grant Aerona3, the next step is a survey that checks heat loss, emitters, hot water, controls, and property layout before the product is chosen. According to MCS (2025), compliant performance depends on documented design and commissioning rather than on product messaging alone.

Electromatic can show where each route makes practical sense for London and Surrey housing stock and whether the wider project should also include solar PV or battery storage planning. 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 answer rather than a narrow R290-versus-R32 debate. It also makes quote comparison easier because the real assumptions are visible before you commit. It also helps show whether the apparent technology advantage actually matters in your rooms, or whether a simpler mainstream route is enough. That is often where the best-value answer appears. It also keeps the decision tied to delivered comfort rather than marketing hierarchy. That usually improves final quote scrutiny. It also sharpens upgrade decisions on radiators and controls. That makes scope risk easier to judge. It also strengthens budget control. That matters on real retrofit budgets.

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Frequently Asked Questions

Most follow-up questions on Mitsubishi Ecodan vs Grant Aerona3 are really about whether newer R290 positioning automatically beats a mainstream R32 route. According to current manufacturer positioning and MCS principles, the answer remains property-specific because design and commissioning still decide the result.

How much does Mitsubishi’s R290 refrigerant matter?

It matters if lower GWP and a more future-facing product direction are important to you, but it still does not replace proper system design.

Can Grant Aerona3 still work well in older homes?

Yes. In many homes it can be a sensible mainstream answer if the radiators, controls, and hot-water design are handled properly.

Does Mitsubishi suit harder retrofits better?

Sometimes it can, especially where higher-temperature reassurance helps the installer justify the design, but the property still decides.

Can both systems work with existing radiators?

Sometimes yes, but only if the radiators are genuinely suitable or can be upgraded sensibly as part of the design.

Which option makes more sense in Surrey and TW homes?

The better option is whichever route your installer can size, explain, and support most clearly for your property. 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