Mech Design for “Pretty Good” addition/retrofit
We are expanding a 1bd/1ba cabin into a “not too big” 4bd/3ba family home, and I am struggling to work out the mechanicals. We are working on modeling so that will obviously inform the selections, but I would like to hear from you folks if you have other suggestions we should be looking at as we get into modeling everything.
Zone 7 – near Two Harbors, MN.
For the mechanicals I have a mixed bag that I am guessing is overkill and needs editing:
1. “Right sized” Navien, Viessmann, or IBC boiler – Prep for solar collector preheat?
2. Expand existing slab-only hydronic to slab in addition and Jaga/Runtal/SlantFin radiators in bedrooms/bathrooms
3. Domestic Hot Water – Indirect tank? Heat pump water heater?
4. RSF Opel fireplace (EPA2020 via catalyst)
5. CERV heat pump air exchanger
6. Ductless cool/heat (install one head upstairs in classroom/hall and pre-wire/plumb for second head on ground floor South elevation, opposite kitchen
We do have LP onsite but I aim to minimize our dependency on LP deliveries (not only for environmental concerns, we have a 1/4mi sloped driveway that gets icy and narrow in the late winter). I can’t entirely eliminate it because our shop/studio/office building has a mod-con boiler providing hydronic heat and DHW. But the house will switch from LP to induction range, and from LP dryer to electric condensation.
We homeschool our 4 kids so we truly “live” here when we are not traveling, so getting a nice, consistent setup is really important. The previous owners were totally off-grid and I suspect they went for a time without running the air exchanger, and the result is the windows have been compromised. We are planning on replacing them all with Duxton triple-pane fiberglass. Between that and the fact that the only heat is from the radiant slab when we are not here feeding the stove (we currently have a Jotul we love), there is a bit temp delta between the basement and the upstairs bedroom where the kids currently sleep.
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