Tanks or no tanks: customizing a combination of DHW and hydronic
I’ve spent some time in the archives here, and am grateful for the wisdom therein. It’s clear that each situation is different, and I thought perhaps I could crowdsource the best solution for mine.
I’m building myself a 900 sq.ft. house in northern Ohio. We’re going for LEED platinum, and a HERS score in the 50’s. Heating and cooling is primarily with a double-head minisplit, the best money can buy. So I hope it will handle all heating needs down to 10F outside temp. or thereabouts.
Supplemental heat will be radiant hydronic in the floor, which is cheap to install in a new build. I have no access to gas onsite, so supplemental and DHW will be electric.
QUESTION: Weighing all factors (upfront cost, lifespan cost, efficiency, elegance/simplicity, durability) what might be the best route to accomplish these two electric water heating tasks? A single unit performing both, or separate units optimized for each task?
I’m inclined against an open loop for the radiant, for health and corrosion reasons, but would still consider it.
Seems like the best would be a small tank for DHW, since my wife and I have a low but steady need for hot water. But a small tank does not have the juice to also heat a slab a couple times a year.
It’s conceivable that some years the radiant would not be used at all, so it has to be able to sit for long periods of inactivity.
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