Hello all,

Designing home in zone 6, slab on grade. Shooting for ACH50 of under 1.5 and well insulated.  2 BR, 2BA, open concept, roughly 1700 SF, all electric, solar-ready. Will also have efficient wood stove. I know, I know. But we love a real fire. 

Question around HVAC choices. 

Air to air heat pumps, ducted or inducted, would be easy choice. My experience with my Fujitsu high all mount mini split dries out the air in winter (relative humidity in my cabin gets to under 20% when mini split is creating heat) and produces an undesirable breeze. Maybe the Mitsubishi low-profile, floor-mount units would solve the latter issue.  So, considering other options. 

Other option:
1. Hydronic in-floor or radiator heat. With slab on grade, have finished concrete floors and money saved on additional flooring goes to in-floor hydronic system.  Thinking air-to-water heat pump for both domestic hot water and hydronic heat. Is this a reasonable approach? Is this technology gaining enough use in the US to have enough data points for forming opinions?

Not many A2W systems in my area. That alone could be enough to steer clear but the technology seems very interesting. 

Would still need efficient AC solution. 

For ERV, either through-wall units or ducted unit. Without basement not sure where the ERV and ducting would go–mechanical closet and flex ducts through attic? Mount unit in attic?  Either way, does the attic need to be conditioned for during and/or unit install?

Guessing some of you have been down this decision road and may be able to help this analysis paralysis. Thank you.

Jim