From all the information I have got the fugitsu units are better for heating will go past the -15 while the Mitsubishi are better for cooling and will go to -13 (read max of -18). The fugitsu's are little cheaper. Both companies sell single head units or mutihead units.

I got a Mitsubishi 1.5 ton hyerheat and worked great this past winter and like it Then I wanted to add another this year but a .75 ton fugitsu this time. Could not find enough info on a ducted unit so went with a floor model. The mutibushi model was almost twice as much on a floor model which swayed me this time.

I missed that you don't like the wall hung. Check into the floor mounted ones. There nice and easy to mount and can fit under Windows. Mitsubishi sells them in the mxz muti heads or check fugitsu halcyon single head and xlth muti head units.

Thanks toadman77

I didn't know they had floor mounted units. Would you go with one three head or maybe a single and one 2 head.

Im not sure on your setup or how many btus you would need. You could get a load calculation done. I didn't get one but figured my own and also looked at my electric usage and figured out the estimated btus.

On the number of condenser; It depends if you don't mind the condensers outside the house. You will also have to keep them up out of the snow. Google how to buy a ductless mini split. It a good write up .

Also if you do the floor mounts You can run the lines in the basement and to the outside. You also will need a drain in the basement or somewhere outside to drain the condensation pipe from running ac on it also. The problem I had with the ducted units is how far to run them and trying to figure a return since I was doing some of the install.

Ducted mini split vs. small conventional central unit, what is the difference? I think that the answer is static pressure. That probably means little in function. I think that you need to choose the system that gives you best low temp performance.

See my other post today about mini splits in this forum. What about ceiling cassettes?

Ionized

Not big on ceiling cassettes but the floor mount is looking better.

Don't forget that mini splits don't have electrical resistance heat to carry you over the defrost slumps. The high mass slab heat obviously won't be nimble enough to do that either. Obviously in a house with low heat loss, that is less of an issue than in a home with poor insulation and air-sealing.

ionized

The house will be will insulated, sealed, with triple glazed windows so heat loss will be slow. I wasn't aware of the defrost slumps. How often and for how long do they last? The propane fireplace should be able to handle heat loss in the living area.

My Mitsubishi is about every 45min to 55 min below 35 degrees. The longest I had was 10 min for a defrost but usually 4-7min. It wasn't that noticeable until it was in the single digits. Having the other unit will make it less noticeable.

I assume that mini splits all have on-demand defrost. Originally, heat pumps all had timed defrost. The frequency of defrost was set by the installer and the defrost period was set by the installer. With on-demand, sensors determine how long based on the temperature of the coils and possibly, when defrost is needed. Ending a defrost cycle must depend on a rapid rise in coil temperature that occurs after the ice melts. The amount of defrost needed is dependent on outdoor temp and humidity. During defrost, heat pumps are actually reversed from their heating mode. My mini splits close their vanes and stop the blower.

Mine unit keeps the vanes straight out; like when it usually just on without the compressor running. The fan is off to. The longest was 10 min when it was -0s.