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Comment by adrianmonk | Hacker News Reader

Mitsubishi's products seem to be mini-split systems[1].

--> EDIT: Or maybe not... they seem to offer forced-air too. <--

The DOE challenge is for ducted systems. Their site[2] says:

> The Challenge is currently focused on residential, centrally ducted, electric-only HPs.

The DOE challenge also has other requirements[3] that I don't know if the Mitsubishi systems satisfy. It requires certain levels of efficiency and "grid interactivity" (meaning Energy Star "demand response"[4] where your utility can temporarily tweak your thermostat settings).

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[1] https://www.mitsubishicomfort.com/residential/new-products

[2] https://www.energy.gov/eere/buildings/cchp-technology-challe...

[3] https://www.energy.gov/sites/default/files/2021-10/bto-cchp-...

[4] https://www.energystar.gov/sites/default/files/ENERGY%20STAR...

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Many of the Mitsubishi heat pumps work with central ducted systems just fine. I have one (replaced a central gas heat, electric AC system). It’s just a different air handler but the heat pump was the same as would have been used in a mini-split install.

When cross shopping the Mitsubishi vs Trane, the Mitsubishi was miles ahead. I didn’t even get the most cold weather efficient option (not needed for my climate).

Oh, you must be right. I was finally able to find this on Mitsubishi's site:

https://www.mitsubishicomfort.com/residential/products/ducte...

And that says it's compatible with some "hyper-heat" outdoor units. So apparently they do offer both.

How did you find a Mitsubishi installer? I like the product but couldn’t find a contractor in the Portland Oregon area.

I used Mitsubishis site to find the local “diamond” contractors (those factory trained and do enough volume). Then cross referenced vs yelp.

https://www.mitsubishicomfort.com/find-a-contractor

I see a few in Portland and several in nearby zip codes. Hopefully one can work for you. There are different tiers of “diamond” so you can compare if the difference matters to you.

One thing that’s a bit different is the air handler and outside compressor run on one circuit (mine is a 3 ton unit). So there’s a power line between the 2 units. That threw off our city inspector. But it works out nice since I now have an extra 20A breaker free :)

Thanks! Do you have the technical docs with the efficiency curves for the Mitsubishi ducted systems? I can’t find the materials amongst all the marketing.

For example this is the Carrier Infinity 24 we are considering. https://d1049ui2fjityy.cloudfront.net/userfiles/inriver/docu...

For reference, here’s what we have: 36KBTU AIRHANDLER/HEATPUMP HI-STATIC M SERIES DUCTED SYSTEM INDOOR MOD# SVZ-KP36NA OUTDOOR MOD# SUZ-KA36NA2

It’s a slightly older model as we had height restrictions to work around. This prevented us from getting a newer or hyper heat model. IIRC ours had good efficiency into the 20F range which was plenty for us.

In comparison, the Trane dropped efficiency at 50F and needed heat strips at that temp (so pretty crap).

I found it in their catalog. You’ll need your model or series. After all the specs there were some efficiency/temp tables. It was under Pros (vs homeowner) -> USA -> product support -> catalog -> m and p series.

Catalog:

https://mylinkdrive.com/viewPdf?srcUrl=http://enter.mehvac.c...

pocket guide:

https://mylinkdrive.com/viewPdf?srcUrl=http://enter.mehvac.c...

I wonder why ducted systems were part of the requirements, is it because it's just aimed at the USA and then mostly at adoptability for existing systems (which seems to be ducted mostly)? I only have anecdotal experience and no numbers to back that up, but it's the only reason I can come up with that would put such a restriction in place.

I'd say rip the ducts out and just use split systems but I imagine other people have thought about that and figured it's not the best way to go. (or at last not in the US)

Yes, because nearly every house in cold climates is ducted, and we’re trying to get people off oil heating quickly, easily, and cheaply. Popping a new heat exchanger in an existing furnace is stupid simple compared to running coolant lines to new, wall-mounted exchangers all over the house.

I think that's true, if the ducts exist already that's simplest and cheapest. If they don't mini-split type systems are. But I suspect that long term those are going to be a pain in the butt because you have a lot of failure points.

Mini splits seem to be pretty reliable. They’re very common outside of North America. Most of the leading manufacturers seem to be from Japan (Mitsubishi, Fujitsu, Daikin)

Hydronic heat distribution (baseboard and radiators) is quite common in New England.

Sorry, meant to mean "in the US", since this was an American Government competition.

New England is part of the US.

Not in any construction in the last 50 years.

Kind of a shame, ducted heating has a lot of issues, but is the best for retrofit I guess.

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