Can I use Pucks w/ both mini-splits & baseboard hot water?

I have a two-story, 2400 sq. ft. home in southern New England. Its heating is primarily from a high-efficiency oil-fired boiler with hot-water baseboard heat. In a few places we have electric heaters (in bathrooms) or fan-assisted radiators. The house has 3 zones, 2 of which are currently controlled by Nest Thermostats.

The downstairs has a large, open floor plan. The only enclosed area is a small bedroom & bathroom. The rest of the floor is living room, dining area, and kitchen. One Nest thermostat controls the large area, and a conventional programmable thermostat controls the bedroom area. Upstairs has a master-bedroom suite, including a large bedroom, sink area, tub & shower room, and toilet & laundry room. Outside the suite is a small office and a medium-sized bedroom. A single Nest thermostat currently controls the entire floor.

We are planning to install between 3 and 5 Mitsubishi mini-splits. The main purpose is for A/C, but three rooms especially (the master bedroom, upstairs bedroom, and downstairs living area) are either too cold or too warm in winter. So we're also looking for heat to fine-tune the hot water system.

Can we use Puck thermostats to control the mini-splits? Can they coordinate with the Nest thermostats? How would they split heating responsibilities between the mini-splits & the baseboard heat? Can you offer any other advice that might help this project?

Thanks

Elia Zaitsev

August 23, 2018 16:29

Interested in this as well as I have a similar setup. Nest is setup to control the oil-fired hot-water baseboard, and Flair puck controls a Mitsubishi mini-split which is can do A/C and heat. As I understand it (and have it working right now) the Nest can control the set point for the Flair, but only if the Flair is set to auto. Not clear on if the Flair can change the setpoint on the Nest (which I really don't care much about), or how the Nest/Flair will react if I set the Nest's setpoint to a cold temperature if it's configured currently to do heat only. I speculate the right answer is to set the Nest to control heat/cool, even if the Nest doesn't know it has a cooling device connected; it would indirectly control the A/C by passing the setpoint to the Flair.

I'm a bit wary of trying this as I don't want to damage the boiler in anyway. I'm also wondering if and how it would be possible to handle the fact that there are two heating systems now, the oil-fired baseboards AND the Mitsubishi's. I would probably prefer to use the Mitsubishi most of the time and save the oil-boiler as backup for extreme temperatures...

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