I'm looking at having a Fujitsu mini-split installed in my home. I'm going with the 15,000 btu unit, I live in Central Maine. My question is should I go with the regular unit that's rated to work down to -5 F with an HSPF of 12, or the newer model XLTH rated down to -15 F with an HSPF of 10 ? I guess the big question is just how big a deal is the HSPF rating ? The XLTH unit is also $100 more, no biggie if it works better in sub zero temp.
Help choosing a Fujitsu heat pump
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Highbeam
Minister of Fire
Just because the unit "works" in -15 or even -5 degree temps does not mean it makes all 15000 btu of heat. It might only make a small percentage of rated output at those temps. Some folks, like mitsubishi hyper heat models, actually specify that their product will provide full rated output down to 5 degrees so you know what you're getting.
I believe that the ability of the heat pumps to make a certain amount of heat at all possible temps is critically important to the adoption of this technology in a heating area.
So to your situation, are you heating with it or just cooling? Is this supplemental or primary heat? How cold does it get at your location? Does Fujitsu specify whether those models make 10% or 100% of their rated output at those low temps?
I believe that the ability of the heat pumps to make a certain amount of heat at all possible temps is critically important to the adoption of this technology in a heating area.
So to your situation, are you heating with it or just cooling? Is this supplemental or primary heat? How cold does it get at your location? Does Fujitsu specify whether those models make 10% or 100% of their rated output at those low temps?
mass_burner
Minister of Fire
If the primary purpose of the unit is heating, but you don't care about how well it works when its sub-zero, then I'd stick with the regular unit. There is a small efficiency penalty (as you can see by the rating) for the units that have the extended cold temperature ratings.
I would go for the best built and highest heating spec for your climate. Make sure you have the numbers correct. The XLTH should have the higher [email protected]. I would also look at the best Mitsubishi and Daikin units before deciding. This report may be helpful, though it is from 2011 and tests older models. http://www.nrel.gov/docs/fy11osti/52175.pdf
Note that their results for the Fujitsu often exceeded the manufacturer's results. This corresponds with the product info supplied by Fujitsu. The XLTH is tested to put out 15000 btus at -10F (18,000 btus at 20F). It uses a larger compressor and evaporator to achieve this. This sounds like a better fit for Maine.
Daikin LV series has an HSPF of up to 12.5 (11.6 for the 15K unit) and is built very well. I would also look at them. We had a detailed report a few year back of an installation in Nova Scotia that performed excellently.
http://www.daikinac.com/content/residential/single-zone/lv-series/
Remember that this is an area heater. Regardless of the final choice, just like with a wood stove, be sure that the unit is correctly sized for the area that is to be heated.
Note that their results for the Fujitsu often exceeded the manufacturer's results. This corresponds with the product info supplied by Fujitsu. The XLTH is tested to put out 15000 btus at -10F (18,000 btus at 20F). It uses a larger compressor and evaporator to achieve this. This sounds like a better fit for Maine.
Daikin LV series has an HSPF of up to 12.5 (11.6 for the 15K unit) and is built very well. I would also look at them. We had a detailed report a few year back of an installation in Nova Scotia that performed excellently.
http://www.daikinac.com/content/residential/single-zone/lv-series/
Remember that this is an area heater. Regardless of the final choice, just like with a wood stove, be sure that the unit is correctly sized for the area that is to be heated.
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Some additional helpful discussion here:
https://www.hearth.com/talk/threads/impressed-with-the-daikin-ductless-heat-pump.60963/
https://www.hearth.com/talk/threads/impressed-with-the-daikin-ductless-heat-pump.60963/
DBoon
Minister of Fire
Hi BJN644, I have a Fujitsu 15RLS2H. Aside from the maddeningly overcomplicated control system that I can't seem to be able to set on a "daily timer" mode, the system is great (Note: I would expect maddeningly complex controls from all Japanese heat pumps).
I wouldn't pay too much attention to the HSPF unless the units you are comparing have the same low temperature cutoff. Oddly enough, when I was looking at the Fujitsu, the contractor recommended the unit that would only heat when the outside temperature was warmer (I forget what the model number of that was) because "it had a higher HSPF, and that's what you should pay attention to." This made no sense, and I can only attribute the higher HSPF on the other unit to the fact that it stopped providing heat at a higher temperature, so was then naturally more efficient overall when it was heating.
I was amazed the first time it got down to 0 degrees F and I put my hand up to the inside unit output and it was very warm.
Essentially, I am using the 15RLS2H to provide baseline heat to a not super-well insulated house that I am undertaking a several year renovation on. I would estimate that I would have used 550 gallons of oil to keep the house at 55 degrees F in the winter (8000 degree day climate, and this year was every bit that), but I only used 125-150 gallons of oil and about 4 MWh of electricity (mostly from my net-metered solar PV array) to keep the house that warm for the winter. At this rate, I have about a 2 year payback (system cost with install was $3200). I think my overall COP for the winter was 3+
I wouldn't pay too much attention to the HSPF unless the units you are comparing have the same low temperature cutoff. Oddly enough, when I was looking at the Fujitsu, the contractor recommended the unit that would only heat when the outside temperature was warmer (I forget what the model number of that was) because "it had a higher HSPF, and that's what you should pay attention to." This made no sense, and I can only attribute the higher HSPF on the other unit to the fact that it stopped providing heat at a higher temperature, so was then naturally more efficient overall when it was heating.
I was amazed the first time it got down to 0 degrees F and I put my hand up to the inside unit output and it was very warm.
Essentially, I am using the 15RLS2H to provide baseline heat to a not super-well insulated house that I am undertaking a several year renovation on. I would estimate that I would have used 550 gallons of oil to keep the house at 55 degrees F in the winter (8000 degree day climate, and this year was every bit that), but I only used 125-150 gallons of oil and about 4 MWh of electricity (mostly from my net-metered solar PV array) to keep the house that warm for the winter. At this rate, I have about a 2 year payback (system cost with install was $3200). I think my overall COP for the winter was 3+
Thanks for the reply, the unit you have and the 15RLS2 are the two I'm comparing. The specs from Fujitsu show the BTU output of the 15RLS2 at 16,700 @ -5F, the chart stops at that temp. so I don't know how it performs in colder temps. How much power do you save with an HSPF of 12 vs. 10.3 ?
flyingcow
Minister of Fire
I have 2 Mitsu HP's and have been very impressed with the heat output vs elc useage. And it's 86f outside right now......nice dry 72f inside. 
. Same unit
I anticipate you'll be very happy with the HP. To be able to heat and cool with a HP up here in the north, it's a win win for me.
. Same unitI anticipate you'll be very happy with the HP. To be able to heat and cool with a HP up here in the north, it's a win win for me.
DBoon
Minister of Fire
Again, I would ignore the HSPF. When the "hyper-heat" versions have a lower HSPF than the non-hyper heat versions, but the heat output above 0 degrees F seems the same (according to the output curves, which are not easy to find or understand), then that tells me that the HSPF unfairly penalizes a unit that does manage to heat well at lower temperatures.
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