2nd story with Bonus Gypecrete VS Mini Split

[SNOW JW]

I was hoping someone could help me out with my choice.

I have 700sqft of 2 bedroom & 1 bath then I have 700sqft above the garage. New construction with great insulation plans. I already have slab on grade 95% boiler with in floor heat in house & garage (love in floor heat) I live in Belgrade MT so I do get some pretty cold nights.

It's about $2700 to Gypecrete in the 2 bedroom 1 bath area. (can't do gypecrete above the garage because of weight loading)

So if I did gypecrete it would be easy to heat evenly but no AC & I still have to heat the above the garage area & no AC cooling.

2nd option. Do 3 mini split system pick up the bedrooms & one in bonus room. Then how do I heat bathroom & supplemental heat for the cold nights?? Would or should I do Hydronic baseboard or electric baseboard??

What would you do?? The upstairs will not be used often so the mini splits are nice to lower that temp way down then when I have company or we do a party in the mancave above the garage crank them up.

Thanks for the help

 

[yeldogt]

My shore house is a large extended cape cod -- the second floor is two large bedrooms and one big bath in the middle.. I previously had a conventional split AC system in the attic for those three rooms. The house uses panel radiators for heat in those areas. 2 in each bedroom and one in the bathroom -- running off the boiler.

When the AC failed -- I ripped the problematic unit out of the attic -- Insulated and closed off the attic and installed two mini-split cassettes style in each of the bedrooms.. They rock -- no problem with air not making it to the bath -- they eliminate any/ all humidity. Mini splits cost just as much as putting in a new conventional system -- it's not a cheap way.

While I have the radiant panels w/ individual thermostats -- But - the HP's could easily keep the space warm in the winter.

Is there a way to get PEX to that area ?? Maybe just do the bathroom ? When well insulated things don't need as much heat. Maybe even electric mat under bathroom floor with a timer.

 

[SNOW JW]

yeldogt.

Yes I can put Hydronic baseboards in each room very easy & run off my boiler.

Maybe I am getting carried away with to many heads would one head heat 2 small bedrooms & a bath?? Leave doors open in daytime? Then I could run the upstairs off 2 heads and downstairs off 2 heads.

What high efficiency units that heat well in low temps should I be looking at??

 

[SNOW JW]

double post

 

[yeldogt]

Mitsubishi hyper heat is by all accounts still the best -- high heat rapacity when temps dip under zero. I read about super insulated houses only having one head per level -- it must work in open floor plans with very tight building

-- My cape needed one in each of the two bedroom on that level ... works well.

I guess it all about expectations.

Do you have NG?

With NG and a boiler -- I would be looking at some form of hydronic. You can install more baseboard and keep your temps down -- closer to the rest of the floor temps. One AC unit for a level works better IMO vs one heating unit. Baseboard is typically run at 180 degree water .. with more fins you can increase the output with lower water temps.

I use panel radiators with continuous circulation fittings ---boiler uses outdoor reset. Simple PEX to each unit. They hang on the wall -- it's how everything in Europe is heated

 

[SNOW JW]

No I have propane. Running 2 heat levels kinda ***** but it can be done as I will loose some of my condensing efficiencies of my boiler but hopefully it doesn't have to kick on very often.

 

[mrpizza]

2 small bedrooms and a bath sounds like a perfect application for a ducted mini split. They are used to run 2-3 4 or 6 inch runs off of it with a small return. They do have a very low max static pressure, typically .2 or .3, where a conventional hvac system can be as high as 1.2 or thereabouts.