Floor Mounted Heat Pump Efficiency
Im doing a DER on a three unit building (relatively small units). 7a cold climate (Winnipeg). In keeping it simple, I am looking at one ductless HP for each unit. Radiant cove electrical backup heaters. I originally had my eye on the Mitsubishi Hyper Heat Plus head unit (MSZ-FS09NA & MUZ-FS09NAH). However, the Mitsubishi Hyper Heat floor mounted unit (MFZ-KJ09NA & MUFZ-KJ09NAHZ) publishes significantly greater COPs in the colder temperatures [COP (8ºC, -8ºC, -15ºC): 4.30/2.82/3.68 vs 4.54/2.43/2.21]. The floor mounted unit also shows greater moisture removal (1.4 pt./h vs. 0.6 pt./h). It was previously my understanding that the head units were the most efficient, especially the “plus” unit. Does anyone have any positive experience with the floor mounted units, especially for getting good air mixing?
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I would doulecheck the data sheet, that looks like a misprint. You can check the full engineering data for the unit here:
https://mylinkdrive.com/USA/M_Series/R410A_Systems-1/Outdoor_Equipment/R410A_Outdoor
There is nothing wrong a floor mount unit, they work very well in a cold climate. They are also a bit easier for maintaince.
My $0.02, wall/ceiling/floor mount units are not zero maintance. The coils and blowers need to be cleaned on them on regular bases since the filter is mostly decorative on the units. It is simple and can work but keep in mind that you have to take care of them. At least on wallmounts the drain lines tend to clog over time which can create a mess if not cought in time.
One of the slim ducted units is a bit more cost and harder install but now you can put a proper intake filter on it so the only maintance is the occasional filter swap. The drains on them are also larger closer to a standard HVAC drain, I haven't had one clog yet.
The slim units from Fujitsu and Carrier/Midea can be mounted vertically so it is pretty easy to install one in the back of a closet or the corner of a room as they only need about 10" of depth.
I would check NEEP's database of units. Some list the indoor unit used and will give real world examples. I doubt they would be that different, but hot air going to the floor would seem to make more sense than from the ceiling for circulating warm air.