Gree Mini-split heat pumps
I’m hoping Dana will weigh in on this question given his expertise with specifying and analyzing mini-split heat pumps.
There are some new heat pumps on the market from Gree that appear to approach the performance of the best units from Mitsubishi and Fujitsu. It appears to me that the cooling efficiency is right up there with Mitsubishi and Fujitsu, though the heating efficiency isn’t as good. They do however specify heating capacity down to -20 degrees F.
Pricing is good, and some of the features (wi-fi) look interesting. I’m interested in them because I mostly need cooling, and only want the heat function as an emergency backup to the gas fired hot water system in my house.
I’d be interested to see a quick comparison of these new units vs other top performing heat pumps.
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I have zero experience with Gree, let alone the Crown series, but have vague memory of hearing about reliability issues with other models. I recommended a Gree to a DIYer a few years ago as a lower noise yet still inexpensive alternative to a PTHP for a sound studio he was building in a detached garage, but don't know if he in fact went that route.
They're pretty gutsy to specifiy output a -30C/-22F, and I suspect they don't have a lot of experience operating them continously at very low temps. There's no indication of pan heaters for clearing defrost ice to avoid damaging the fan on the outdoor unit, for instance. Pan heaters are standard on the Fujitsu RLS3H series, and a required accessory to keep the warranty valid on Mitsubishi equipment below some outdoor temp. Any equipment can run long enough at low temps to specify an output, but it's not always a good idea to run it there unless specifically designed for low-temp operation.
HSPF tested efficiency of the Crown series is in the 10s, comparable to the older Mitsubishi FExxNA series mini-splits, but lower than the HSPF 12-13 of the FH series, and WAY below the HSPF 13-14 of the Fujitsu RLS3H. Comparing the 1-tonners:
http://17uo7e27w1attiybs22of10v.wpengine.netdna-cdn.com/wp-content/uploads/2015/05/Crown-Submittal-CROWN12HP230V1A-V0.pdf
http://usa.mylinkdrive.com/uploads/documents/1642/document/MSZ-FE12NA-MUZ-FE12NA_Submittal.pdf
http://usa.mylinkdrive.com/uploads/documents/4561/document/MSZ-FH12NA_MUZ-FH12NA_Submittal.pdf
http://www.fujitsugeneral.com/PDF_06/Submittals/12RLS3HSubmittal.pdf
The $400-500 premium for the hardware (at internet pricing) for the1-ton Fujitsu 12RLS3H delivers 33% more heat per kwh than the 1-ton Gree, and has as much or more capacity at -15F the Gree has at 0F too. The minimum modulated output of the 1-ton Gree @ 47F is 3070 BTU/hr, comparable to the 3100BTU/hr of the Fujitsu. It also buys you an SEER of 29+ to the Gree's 23.
On the lower price point end of the scale, the LG LS120HSV4 has comparable SEER/HSPF numbers to the Gree, and may be a better value- comparable to or somewhat cheaper than the Gree, possibly with more distributor & tech support(?). It dials back to ~1 kbtu/hr in either cooling heating mode, which means it's almost always modulating a low speed rather than cycling.
http://s3.supplyhouse.com/product_files/LG-LS120HSV4-Submittal-Sheet.pdf
It's only specified down to -4F- not sure if that's a show-stopper(?). I don't have any first-hand experience with these either, but I've notices LG compressors on buildings all over the place on the MA Cape & Islands (warm edge of US climate zone 5) and very few Grees,
At lighter heating loads mini-splits are usually cheaper to operate than condensing gas even in high-priced electricity markets. At minimum modulation and at 45-50F outdoor temp they'll be running COPs in the 4s, sometimes 5s, comparable to best in class ground source heat pump heating efficiency. You may be thinking of it as only emergency back up heat, but end up using it heating mode more than you expect- they deliver very stable room temps when modulating, using a "set and forget" strategy.
Doesn't Gree make the Trane mini splits? And is this the Joshua Van Tol who's a firmware/software engineer at Trane? (I searched LinkedIn, I'm snoopy I guess) If so, then full disclosure! If not, my apologies.
Joshua, what climate are you in?
Dana,
Thanks so much for the thoughtful commentary. I'm in southeastern MN down in the river valley, climate zone 6. Some years we get quite a bit of warm humid weather during the summer, and of course we have a real winter, with pretty long shoulder seasons.
在回答比尔Dietze,我为交易工作ne, but I can't really comment on who we source equipment from. In any case my objective here is to understand the limits and capabilities of the available equipment so that I can make a good choice.
解决Dana的建议,可能是他per to operate a mini-split during the shoulder seasons, he could well be right. A quick back of the envelope calc I did a while back indicated that the crossover point was probably around 40 degrees F, but that was a very rough calculation. Arguing in favor of this idea is the fact that our electricity is relatively cheap, at $0.12 or so a KWh all in, and that rooftop solar is in our future. Arguing against it is the fact that gas is also pretty cheap here, and the condensing boiler and massive cast iron radiators in the house work very well indeed.
At this point the Fujitsu units are looking most attractive, though Mitsubishi is more popular in my area and would likely be easier to get parts and service for.
Access to local distributor support is important if you are using it as a primary heating appliance, but less so if it's only auxilliary heating in the shoulder seasons or as temporary back up while waiting for the hydronic system to be repaired.
In comparing the Fujitsu units to the Mitsubishi FH series, ton-for-ton the Fujitsu RLS3s have more low-temp capacity and slightly higher efficiency, but the 3/4 tonners don't modulate as low as the Mitsubishi units. The 9RLS3 only throttles back to 3100 BTU/hr min @ 47F, compared to 1600 BTU/hr @ 47F for the FH09NA, which means you'll get far more modulating comfort out of the FH09NA for shoulder-season heating.
The spread is narrow for the 1-tons 3100 BTU/hr vs. 3700 BTU/hr for the FH12NA, but it's advantage-Fujitsu. For the larger sizes the Fujitsu units all idle down to 3100BTU/hr @ 47F, but the FH series all have higher minimums See:
http://www.mitsubishipro.com/media/946493/fh_product_guide.pdf
http://www.fujitsugeneral.com/PDF_06/9-12-15RLS3%20Sell%20Sheet.pdf
At typical heating & cooling ratios for zone 6 houses, cold climate mini-splits sized for the cooling loads won't have sufficient heating capacity to cover the whole thing at negative double-digit outdoor design temps (unless it's a way-better-than code min house), but PLENTY of capacity for shoulder season use.