Sizing a mini split heat pump question
In my climate, both heating and air conditioning is important, though heating is much more dominant here in the mountains. I’ve completed a Manual J for heating a home we will be building this year.
Our outdoor 99% design temp is 16 F, giving us a heating load of 16,350 BTU at that temp. Our heating load at 47 F is around 7,000 BTU, and the few nights we drop to 5 F would be 19,700. We’ll have backup heat with a propane stove, so I’m not too worried about severe cold. I don’t believe I need a hyper heat mini split.
I’ve identified a few mini split models that I think would work well for us, and I would like some feedback. I’ll also be speaking with some HVAC contractors, too. My goal is to have our mini split be in a modulating state for most of our winter.
One of the models I’m looking at has a max heating capacity of 18,000 BTU down to 5 F, and a minimum capacity at 47 F of 5,150 BTU. I believe that would allow this mini split to be mostly modulating for my home with outdoor temps between about 13 F – 53 F. It would be going all out at around 10 F, and start cycling by 55 F or so. (I played with various outdoor temps in our Manual J to determine the heating loads at each point.)
Does that sound like a good size for our house? I’m just hoping I can find an HVAC contractor that won’t insist on over-sizing our equipment.
I would actually prefer a mini split that could continue to modulate at somewhat higher temps, but most models I’ve found so far that could do that would then be running all out at our 16 F design temp instead of continuing to modulate at a bit lower temps. Not sure which option is best, or if there are models that could actually do both. Any thoughts? Am I missing anything?
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