Ductless mini split sizing advice - Mitsubishi specific
We are going to have a Mitsubishi heat pump installed in our house (in progress) soon and would be interested in some thoughts on sizing.
The house is in Jackson, NH 03846 (climate zone 6a). It's cold and snowy, but we have great passive solar gain, open floor plan, tight construction, and high insulation values. We have wiring in place for regular electric resistance backup. Our Energy Star rater calculated our heat load at 11.2kBTU / hr at design temp (-6F, 65F inside, based on St Johnsbury VT).
Looking at the new Mitsubishi FH line, MSZ/MUZ units:
We are leaning towards the FH12NA for lower cost and greater efficiency. Its rated capacity at 17f is 8k BTU/hr and can operate at max capacity of 13.6k BTU/hr down to 5f.
The FH15NA has a rated capacity of 11k BTU/hr at 17f and operates at max capacity of 18k BTU/hr down to 5f.
I'm pretty sure either unit will work, we might just have to rely on the electric resistance backup a bit more with the smaller unit during the coldest parts of winter. I believe most of December through early March, it regularly gets below 10f at night.
Do you think the FH12NA would be working too hard during the colder months and does it make sense to go with the FH15NA? Or stick with the FH12NA because it's rated as more efficient and will work, just with the chance of a bit more electric resistance backup?
Posted May 23, 2014 5:28 PM ET
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