I have a 2nd story bed/bath suite that is currently heated with an electric furnace in the attic. Both the bath and bedroom are served by this unit.
I want to replace the electric furnace with something that is more efficient and can provide some cooling. An regular heat pump won't work because they don't make them small enough (1.5 ton would be extreme overkill for 350 sq ft). A mini-split system would be very expensive professionally installed.
There isn't a good place to install a room heat pump in an external wall.
What I would like to do is to install a room heat pump in an attic wall and rig up something to hook the output into the existing ducting. I will then set up an external thermostat to controll the AC power - this means I wil have to set it to heat in the summer and cool in the winter, but that is not a big deal. I will also have to rig up the return from the existing return. This seems like it would be an inexpensive and effective solution.
Does this seem like it would work?