Hi, we have a 1870 square foot duplex with 3 floors. The first floor is one unit and the second and third floors are another. Currently there’s a natural gas furnace that is ducted into the first and second floors, no registers on the third floor. No cooling. The third floor is converted attic space with 2 foot knee walls. One thermostat, which is in the first floor living room. I have lived upstairs and never had an issue with heat (too much or too little, except of course in summertime), nor have any tenants ever complained. There may only be 2 registers on the 2nd floor, and not one in the bathroom. Again, no complaints for any of the rooms being too cold. I am asking the tenant specifically to see if there’s any more feedback.

Of these two options, which would you choose?
Got two different options, each from a different contractor. I am waiting to get back their quotes, which should come this week.

Option 1: Use a hybrid natural gas/heat pump furnace for the 1st floor for heating and cooling; close off registers to second floor and install ductless mini-splits for second and third floors (1 wall unit in dining room, 1 floor unit in 3rd floor hall).

Option 2: Replace furnace with a new natural gas furnace, keep the furnace for both 1st and 2nd floors; add ductless units, 1 on first floor, 1 on third floor, maybe 1 on second floor.

One of the challenges with option 2 is in Massachusetts in order to get the rebates/grants you need to integrate the system. It may be possible to integrate the furnace just to the first floor head and have the upstairs splits functioning independently. The contractor who came up with this option is still working on figuring out the details.