Mitsubishi Zuba-Central performance data?
I’ve been unable to find any data on the Mitsubishi Zuba-Central except the high heat performance table from 60F to -35F with COP and heating capacity. On GBA someone posted a low heat COP of 2.5 at 5F at 15,000 BTU.
I had given up on the Mitsu because it’s performance was so much worse than the Trane XV19 due to the much higher COP on it’s low speed mode. But if the Mitsu has a low heat mode – then it may be in the running.
During -30C stretch about 15 years ago (we’re in southern Ontario) our house was 20,000 BTU/h and since then we’ve added insulation to the ceiling and floors in contact with the ground, updated all windows to low-E / argon. Modeling with temperature data from the local weather station puts the home heat loss at about 16,000 BTU/hr at -30C after these upgrades so it looks like the Trane can work to about -22C.
BUT – it’s not like anyone tells you how these systems work. When does it switch out of low heat mode and when does it start using backup heat – only when it’s below the minimum temperature? What if it can’t maintain temp. running continously in high heat mode? I’m an engineer and nothing I’ve seen gives me the details I want.
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I am checking with some tech folks at Mitsubishi on this (and by the way, Mitsubishi and Trane formed a "partnership" about a year ago; still separate companies but working together: https://www.trane.com/commercial/north-america/us/en/about-us/newsroom/press-releases/ingersoll-rand-and-mitsubishi-electirc-corporation-to-establish-.html).
Hope to get back to you asap.
Peter
That's interesting to hear. I tried contacting Mitsu and they provided a way to find a dealer ... but it's not as if the ones I've been getting quotes from have the data.
Meanwhile - some research shows that R410A leaks are so signif. that you're better off burning natural gas instead of getting a heat pump - according to a Masters of Climate Change friend. But R290 (basically propane) based heat pumps have been for sale for about 2 years now in Germany and they solve that problem.
Sorry to say that I have not heard back from Mitsubishi high performance team on this.
Your refrigerant leak climate change impact comment gave me pause--really? Sure enough, Brent Ehrlich at BuildingGreen wrote a feature article on this topic in late 2017; here is a short blog about his article: https://www.buildinggreen.com/blog/high-gwp-refrigerants-stealth-climate-destroyers.
Peter
> you're better off burning natural gas instead of getting a heat pump
I took a quick look at the numbers and they indicated that this isn't true. Does anyone have a non-paywall reference?
Jon,
GBA usually has an article to provide an answer to readers' questions. In this case, here is the link: "Which Heating Fuel is Cheaper, Electricity or Natural Gas?"
I'm sorry that I can't help with the paywall problem. It seems to me that GBA information is worth $15 a month -- but if you don't, there are other web sites out there.
> the link: "Which Heating Fuel is Cheaper, Electricity or Natural Gas?"
The title suggests that the GBA article has nothing to do with R410A leaks.
I built my house a year ago. I also considered both the Zuba and the Trane. Given the choice to do it again, I'd go with the Trane instead of the Mitsubishi.
The Zuba doesn't modulate down as much, requires a third party zoning system and was really expensive.
Total cost for the Mitsubishi system was $26,000. An equivalent Trane system would have been $16,000.
It was cool watching the Mitsubishi system hold its own at -30C though...
My one HVAC company came thru with the data in the attached PDF. The Zuba is amazing - but the better efficiency of the Trane XV19 around 5C to -10C makes it come out ahead in the yearly estimated heating cost.
Thanks for adding that!
According to Neri and Zuluaga, at 10% leakage per year, the carbon benefit of a small residential heat pump disappears compared to a top-tier gas-fired hydronic system.
Source : Brent's great feature on refrigerants :
https://www.buildinggreen.com/feature/cost-comfort-climate-change-and-refrigerants
But donate about $10/year/mini-split to some cost efficient carbon reduction program and it's all good.
Show me that 10% per year refrigerant leakage is a credible number first...
I agree - 10% is crazy high. But I'm OK with people contributing a little extra to carbon reduction programs.
So my Zuba system has failed to perform for the entirety of the summer, and short cycles. It provides cooling but no dehumidification. I'm so fed up with it.
I'm thinking of switching the XV19, which has much better low temp COP, quieter operation, and *I think* native zoning. I'm not certain of that one.
Builder shares my frustration, and if they can't fix it soon~ish, they may go with me to get the Mits system ripped out and replaced with a Trane zoning solution
Would be interesting to know more. For some reason it has excessive CFM/ton?
You and me both. They have no valid explanation for the behavior yet. They've already replaced more circuit boards then I can count.