# Which minisplit to get?

Asked by Perry Comeau
Posted Thu, 02/13/2014 - 17:05
Edited Thu, 02/13/2014 - 17:22

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1.

Perry,
Are you sure your house measures 24,000 square feet? If it does, that's a pretty big mansion. Perhaps you meant 2,400 square feet?

Regardless of whether your house measures 2,400 or 24,000 square feet, it is unlikely that a single ductless minisplit unit will heat your house. Moreover, a ductless minisplit won't work when the outdoor temperature drops below about -10F or -15F.

The first step in designing any heating system is to perform a heating load calculation. You can hire an energy consultant (for example, a HERS rater or a mechanical engineer) to perform one for you. For more information on this topic, see these three articles:

Saving Energy With Manual J and Manual D

How to Perform a Heat-Loss Calculation — Part 1

How to Perform a Heat-Loss Calculation — Part 2

Posted Fri, 02/14/2014 - 07:22

2.

The largest single head versions of those series( MSZ-FH15NA or AOU-15RLS2-H) both put out about 15,000 BTU/hr at -15F and it's doubtful that just one of them would come close to heating your house fully at -30F temps, but if your ~36,600 BTU/hr stove is actually keeping up with the load, it's likely that a pair of them would, and one might be good enough to cover your average (but not peak) heat load.

The published HSPF effciency of the Mitsubishi is significantly higher than the Fujitsu at 12.0 compared to 10.3 (that's 16.5% more heat delivered per kwh with the -FH15 than the -15RLS2H).

http://news.mehvac.com/Bulletins/FH_Product_Guide.pdf

http://smartgreenbuild.com/pdf/Fujitsu-RLS2H.pdf

Answered by Dana Dorsett
Posted Fri, 02/14/2014 - 14:21

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