Mitsubishi low temperature specs weirdness: FH06 vs. FH09 vs. FH12
I’ve been using the NEEP Cold Climate ASHP list to compare efficiency of the different mini splits (https://ashp.neep.org/#!/product_list/) and help select the best unit to replace my oil heat in Zone 5 (Connecticut) where we get below zero once in a while…
I really liked the spreadsheet format that was used earlier this year, and used this to chart the Mitsubishi MUZ-FH06NAH, 09, and 12.
It looks like the FH06/09/12’s all use the same size outdoor & indoor cabinets, so my ‘theory’ is that the compressor size increases as you scale up. The smaller units would have higher efficiencies, since there is more heat exchanger area per BTU… And the larger units should perform similar to the smaller units when comparing similar BTU’s (or very slightly less due to start-up of the larger compressor).
The data looks odd for these two cases:
1. The optional low temp data has a minimum dry bulb temp of -13 for the 09 and -12 (and lists N/A for the 06). How could the FH12 have a 14,600 BTU max capacity at -13°F when it’s 13,600 at 5° and 17°?
2.Why would the 06 have 2,100 at (N/A, but assuming -13) but the very similar 09 is 9,900?
I’ve attached the charts, in case it’s useful for anyone else. When I spot checked, it seems the excel data is the same as on the refreshed website that has one unit per page.
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Replies
The capacity at the mystery temperature for the 06NAH is an entry error. If you multiply the specified COP by the power in kW and convert to BTU/h, you get 6400; probably not coincidentally the same number as the 06NA. Not too sure what's going on with the 12NAH rating at -13. There's three different versions of it on the list, or perhaps matched with different indoor units, and two of them say 14,600 and one says 9,900. The higher rated ones do show a much higher input power at max capacity than the lower one.
On closer inspection, the three different versions are just brand label differences; Mitsubishi, Trane and American Standard. They appear to be the exact same units, looking at all the other specs. I suspect that 14,600 value is a mistake as well.
Don't discount the possibility of clerical error when entering or retrieving the data on forms submitted to NEEP. The AHRI submittal sheets for the -NA (no base pan heater) and -NAH (base pan heater included) versions are valid for capacity at -13F.
FH06:
http://meus1.mylinkdrive.com/files/MSZ-FH06NA_MUZ-FH06NA_ProductDataSheet.pdf
http://meus1.mylinkdrive.com/files/MSZ-FH06NA_MUZ-FH06NAH_ProductDataSheet.pdf
FH09:
http://meus1.mylinkdrive.com/files/MSZ-FH09NA_MUZ-FH09NA_Submittal.pdf
http://meus1.mylinkdrive.com/files/MSZ-FH09NA_MUZ-FH09NAH_ProductDataSheet.pdf
FH12:
http://meus1.mylinkdrive.com/files/MSZ-FH12NA~MUZ-FH12NA_Submittal.pdf
http://meus1.mylinkdrive.com/files/MSZ-FH12NA_MUZ-FH12NAH_ProductDataSheet.pdf
The FH15's capacity is 14,580 BTU/hr, less than 0.15% away 14,600 BTU/hr @ -13F, NEEP had down for the FH12, which lend plausibility to the theory that it was a NEEP data entry error (by either NEEP or Mitsubishi.)
http://meus1.mylinkdrive.com/files/MSZ-FH15NA_MUZ-FH15NA_Submittal.pdf
Thanks... I noticed the NEEP COP numbers don't match the submittal sheets either. Could it be different methodology? Seems like a lot of data entry issues if that's the case, and I assume I should trust the submittals? It's a shame, since the NEEP list is nice with everything in one place.
FH09 submittal shows 5° COP as 2.16 - 10900 BTU / 3.41 / 2.16 = 1480W, matches submittal
NEEP has a COP of 2.73 (10900/3.41/2.73 = 1170W).
http://meus1.mylinkdrive.com/files/MSZ-FH09NA_MUZ-FH09NAH_ProductDataSheet.pdf
https://ashp.neep.org/#!/product/25876
AHRI testing requires locking the inverter to 60Hz rather than letting the optimization algorithms control the frequency. The NEEP submittal sheet explicitly requires that the pan heater power NOT be included, but doesn't dictate inverter frequency. Together that may explain at least some of the reported COP anomalies.