First Impressions on Mitsubishi R-454B
We'll update this as we do more installations!
Mitsubishi, long the market incumbent in the cold-climate world (at least in MA), has released their latest R-454B models this summer and we just did our first installation. Here’s our impressions.
What We Like
Profile. Mitsubishi seems to have gone all-in on the boxy profile of the FS units of the prior generation, except this time we have slightly rounded bezels/display corners.
Depending on your aesthetic preferences, this is either nicer or more clunky than LG’s curved mini-splits:
I’d note that these units are like, thick. The LG units are flatter, but then again, this is the FX unit that has the sensor.
Otherwise, seems pretty standard. It almost reminds me of Quilt’s mini-splits, which has gone all the way to the “as boxy as possible” aesthetic, but I almost personally prefer the cleaner, flat look.
GX units. Since these are more narrow than the FX units above, they are more boxy. But the advantage is that they’re great at fitting into smaller spaces:
And instead of a double flap, you have a single flap:
I would recommend using these units for smaller rooms, such as bedrooms.
Turndown. Much better than before. We wrote about this here:
Outdoor units. These are pretty much the same as the prior generation, so no big differences there.
Branch boxes. You can use 1 branch box to connect an outdoor unit to 5 indoor units. LG requires 2 branch boxes (more cost, more complexity) while Daikin avoids branch boxes entirely & consequently can’t connect to 5 indoor units (yet) with a cold climate model. You can actually put a cover on these branch boxes, which means you can mount them outside, which is useful if you’re limited on basement wall space.
Built-in Wifi!! Mini-splits have wifi out of the box! Confirmed!
What We Don’t Like
Electricity. Mitsubishi units hog electricity relative to other brand equivalents. For example, the 3 ton unit requires a 45 amp breaker vs. 35 amps for others. This may be a relevant consideration for those who have tight margins on electrical load.
GX unit boxiness. Self-explanatory, if you’re not into the look.
Missing refrigerant leak detection sensors. A2L refrigerants (which includes R-454B) require refrigerant leak detection sensors, and for some reason, certain ductless mini-split units do not currently ship with these sensors built-in. Mitsubishi support has only recently encountered this error, and may not be as familiar with it.
The fix is simple: you just need to buy the leak detection sensors, and install it. May be a bit annoying if your contractor didn’t expect this upfront, though. We expect this to be resolved by 2026.
Wifi connectivity. Now that I’ve seen LG’s wifi setup first hand, it’s night and day between what LG & Samsung has vs. what Mitsubishi offers.
R-454B. Not as bad of a shortage as before, but still not as good as R-32. Mostly a non-factor during initial installation, but may be annoying if you have a refrigerant leak or have exceptionally long line runs (e.g. 3rd floor triple decker ductless).
Kumo Cloud (rebranded as Mitsubishi Comfort) is actually okay now, but when we tested it, it wasn’t compatible with iOS18. I expect that to be fixed in short order.
The prices! I don’t think there’s anything about the mini-split units themselves that justify an extra 30% pricing premium. Line runs? Same. Mini-splits? Same. Branch boxes? Mostly the same (Mitsubishi has 5-port, LG has 3 & 4 ports, though LG’s configuration process is slightly different).
The thing about being a market incumbent is that you don’t really need to lower your prices unless someone comes in with a lot of volume. I think this is tilted against smaller, local contractors, and as someone who likes local businesses (and dislikes how PE-backed contractors charge way above fair market prices), I don’t like that.
Conclusion
Verdict: Mitsubishi continues to be a solid, leading choice. Their indoor units lean into the boxy look & look quite nice if you’re into that. The outdoor units are the same. Not a bad option by any means, but also not the only option these days.
Want to see all the other options? Take a look here:
2025 Heat Pump Model Showdown
As you probably know, new heat pump models with R-410A refrigerant are phasing out of the market, with newer R-32 and R-454B models taking their place. We’ve been keeping an eye on them at Laminar Collective.