Daikin Altherma 3 vs Mitsubishi Ecodan
Daikin Altherma 3 vs Mitsubishi Ecodan: Two Japanese Giants Compared
Daikin and Mitsubishi are two of the most respected names in heat pumps globally, and both make excellent products for UK homes. If you're comparing these two, you're already in good territory — you're not going to end up with a bad heat pump either way. The question is which one is right for your specific situation.
Here's my honest take: trust your installer's recommendation more than this comparison. But let me explain why, and what the real differences are.
The Specs Side by Side
| Feature | Daikin Altherma 3 | Mitsubishi Ecodan |
|---|---|---|
| Peak COP | 5.1 | 4.6 |
| Refrigerant | R32 | R32 |
| Cold weather performance | Excellent (flash injection tech) | Very good |
| Installed cost | £9,000–£13,000 | £9,000–£13,000 |
| Unit size | Compact — good for smaller spaces | Standard — various sizes available |
| UK installer base | Large and growing | Very large — market leading |
| Track record in UK | Strong | Excellent — 10+ years |
| Warranty | 5–7 years | 5–7 years |
| Controls/smart integration | Daikin Onecta app | MELCloud app |
Where Daikin Pulls Ahead
The headline number for Daikin is the COP of 5.1 — that's among the best in the R32 class. Daikin uses a technology called flash injection, which improves efficiency at low ambient temperatures. This means when it's cold outside and your heat pump is working hardest, the Daikin maintains better performance than many competitors.
In practice, this is most relevant if you're in a colder part of the UK — northern England, Scotland, elevated areas. If you're in the south of England where temperatures rarely drop below -5°C, the advantage is real but less dramatic in day-to-day use.
The Daikin Altherma 3 is also notably compact. If you have a tighter space for the outdoor unit — a small side return, a narrow passage, a compact garden — the Daikin's smaller footprint can be a genuine practical advantage.
Where Mitsubishi Pulls Ahead
Mitsubishi's strength is depth of experience and installer familiarity. The Ecodan has been in UK homes for over a decade. There are more trained Ecodan installers than for any other heat pump brand. That matters enormously.
A heat pump is a sophisticated piece of equipment. It needs to be sized correctly for your home, installed carefully, and commissioned properly — with the correct flow temperature, the right settings for your radiators or underfloor heating, and the controls configured well. An installer who has commissioned 200 Ecodans will do a better job than one who has done 20 Daikins, even if the Daikin is technically more efficient on paper.
Mitsubishi's real-world reliability data across UK installations is also very strong. When you're spending £10,000+ on a heating system, knowing that thousands of similar systems are running well in similar homes is genuinely reassuring.
The Apps: Daikin Onecta vs Mitsubishi MELCloud
Both manufacturers have invested in smart home controls. Daikin's Onecta app has improved significantly in recent years and is now genuinely good — you can set schedules, monitor performance, and adjust temperatures remotely. MELCloud, Mitsubishi's equivalent, is reliable and widely used, though some users find the interface less intuitive.
Neither is dramatically better than the other. Both work well with smart tariffs and home automation systems. Don't let the app be a deciding factor.
The Price Is Essentially the Same
Unlike the Vaillant vs Mitsubishi comparison, where there's a meaningful price difference, Daikin and Mitsubishi come in at very similar costs. You're typically looking at £9,000–£13,000 installed for either, depending on the size of system, any radiator upgrades needed, and your location. This makes the decision genuinely close.
So Which One Should You Get?
This is where I'll be direct: ask your installer, and trust the answer. Here's why that's not a cop-out.
The difference in real-world performance between a well-installed Daikin and a well-installed Mitsubishi is marginal. Both will keep your house warm. Both will give you a COP well above 3 in normal UK conditions. Both are reliable. The spec sheet difference of 0.5 COP points will translate to maybe £50–£100 per year difference in running costs — less than the uncertainty in any efficiency estimate.
What makes a genuinely large difference is how well your system is designed and installed. Flow temperature settings, radiator sizing, cylinder configuration, controls setup — these choices affect your bills far more than which brand is on the outdoor unit.
If your installer says "I've done 150 Ecodans and I know them inside out, I'd recommend Mitsubishi," go with Mitsubishi. If they say "I'm fully trained on Daikin and I think the Altherma 3 is the best product on the market right now," go with Daikin.
One Exception: Cold Climates
If you're in a genuinely cold part of the UK and you get prolonged periods below -5°C, Daikin's flash injection technology does offer a meaningful advantage in maintaining efficiency. In that case, it's worth specifically asking your installer about Daikin even if they typically work with Mitsubishi.
The Verdict
Both are excellent. Daikin edges ahead on peak efficiency and cold-weather performance. Mitsubishi edges ahead on installer familiarity and track record. The price is the same. Follow your installer's lead — their experience with the specific product matters more than anything on a spec sheet. For detailed reviews of each, see our Daikin Altherma 3 review and Mitsubishi Ecodan review. For the full brand ranking, see our best heat pumps UK guide.