I was just going to post something similar, so thank you.

I’m doing 1000sq foot 2 story addition and thinking of doing ductless heat pumps exclusively. (and apply for mass save rebate)

I currently have forced hot air/air conditioning in the existing part of the house and wondering if I can get away with the ductless heat pumps for the addition. I’ll have a gas fireplace on the first floor addition, but just a bedroom on the second floor. Anyone know if this is even allowed in MA? Or will I have to have my existing system ducted into the new space for backup?