I plan to buy and install a new furnace within the next few days. It is for a lower apartment, 800 s.f., that has little insulation. I am replacing a 50 year-old furnace that is oversized, so anything will reduce my tenant's heating bills. I was thinking about a lower effeciency furnace (80%-84%) because of the potential reliability of having fewer parts, and also because the apartment is small.

Any recommedations on brands, either pro or con? I installed a Rheem for the upper unit about 10 years ago, and am very happy with it. I am not sure if the heating suppliers I am dealing with this time carry that brand.