Heating ideas? Pretty efficient very tight home
Building full house R10 slab vertical and horizontal. Walls: Zip R12, R22 batts, 3/4″ airspace behind siding. Sealed Roof: R38 batts, 6″ Firestone ISO above sealed Zip roof deck, Firestone membrane. Windows/doors Loewen Tripane/Dual pane mix.
Heat source in slab radiant & catylytic wood stove
Zehnder fresh air system w/ charcoal type filter for fire season.
So I’m looking to add A/C to the house. Our climate gets cold in the winter and pretty hot in the summer. Of course at night it gets cold and cools the house/slab for the day. We also get fires so sometimes we can’t open the windows for a month or more without smoking up the house, hence Zehnder w/ filter. That brings me to A/C. My thought is to just get mini splits maybe ducted that I hide in soffits so I don’t run any ducting in the unvented roof. Mini splits would also give me a secondary heat source for when we’re out of town in the winter.
Any suggestions?
Thanks
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Ducted heat pump (mini-split or otherwise) gives you the best distribution and can be best matched to your heating and cooling loads. If humidity is a concern in your climate, it'll do that better than a ductless minisplit. Also, does a much better job of filtration compared to a ductless head and much easier to maintain and eventually replace.
What's the planned heat loss? Seems like that will be a cool slab with those levels of insulation.
Thanks for your input. Do you have favorite brand/models? I've only used Fujitsu mini splits in the passed which were super cheap to run and worked better than expected in sub zero temps.
I don't know the planned heat loss, not doing calcs. I've built a couple houses in Montana, one with R20 slab. As long as you air seal very well and site the house properly I personally don't think any slab insulation past R10 is worth the expense and detailing, at least the way we live. Our wood stove runs at night, burns out everyday there is sun even when -25 and the house and slab stay in the high seventies low 80's. Radiant heat never turns on during heating season. The house is long and narrow east/west so the sun heats up the entire slab. Landscaping is hugely overlooked for house comfort in my opinion but most people don't live as rurally as me. I'm sure plenty of people will disagree with me on this but I can't imagine a house being exponentially more comfortable than the ones I've built without being exponentially more expensive and complicated.
I have a ducted Mitsubishi, it's silent and efficient so I definitely recommend. Why the in-floor heat if you have a low load home? Seems like an expensive system that can't provide cooling or filtration.
Honestly, luxury and resale. If this were my forever home I'd skip it. I actually swore I'd never do it again because there is too much time in between running because of solar gain and wood stove. But most people buying/renting my homes will run it full time after the novelty of a wood stove wears off. It also doesn't cost a ton building it myself even with a nice combo boiler. I think with the Mitsubishi, radiant, domestic hot water and zehnder I'll be in it about 20k for a 1950 sf luxury home.
The radiant floor marketing is top notch, even if the surface temp is 72 degrees in a well built house like this.
I guess the next question would be about ditching the zehnder with the Mitsubishi. Does the Mitsubishi do a good job refreshing the air in the house? Problem is the heat would have to run unless it had like a recirculation function. That would be pretty great. I always thought the were just like mini splits with no outside air
It's constant circulation (the blower sips energy) so it moves the air well and can run the fan without the heat on. It can control an ERV but no it doesn't have an ERV.
Ok awesome, I'll dig in. I'm cold climate, so hrv. Thanks