Need RESIDENTIAL HVAC PERSON, experienced with RESIDENTIAL SINGLE FAMILY HVAC equipment, quality of brands, basic design concepts. sorry, DO NOT NEED ARCHITECT OR CAD OR DRAWINGS, JUST ADVICE re furnace replacement questions and some system changes -- 2

Not sure how much detail I should go into here just to find right help, but here's the situation: House built 1950, ranch, 1150sf first floor, 700 sf finished in basement (rest of basement unfinished, no hvac needed). THat 700 sf was built originally to be finished, occupied space, not an after thought. Have to replace 11 year old. Lennox gas forced air furnace. Heat exchanger has failed. AC system is approx 25 years old, also Lennox, operates ok though does not remove quite enough humidity. First floor ductwork has RA on outside walls, SA inboard. Am told by seemingly very capable service tech from major regional company that the cause of heat exchanger failure is initial installation (11 years ago) placed furnace sloping to rear, though manual says it has to be level or sloping to front. Tech says that caused moisture with acid content to erode heat exchanger over time, showed me thick substance that resulted from the erosion. Heat exchanger warranted for 20 years, original installation company will charge around $ 1000. labor. Is it likely there is a way to get them, or Lennox, to cover that labor? If I would have to spend $ 1000 labor to replace heat exchanger, I would forget that, and go for new furnace. Need help with: What brands of furnace / coollng are most reliable? HVAC contractors all have very different recommendations and all say that the brand they sell is good. Heil, Champion, Rheem, Tempstar, etc. Or is there little difference? One contractor seems fairly good, their brand would be Tempstar. Another would be Rheem. Is Lennox good? Are Heil and Champion off-brands and will not last? what furnace design ... 2 stage burner? / 2 stage blower or totally variable? / size? what is correct thermostat to take advantage of all capabilities of furnace heating and cooling? I don't care about remote "smart" operation, just want thermostat to do what's need to take full advantage of furnace's capabilities. Basement finished space with no heating or cooling never goes below 60 degrees, and never above 70 degrees, so its hvac requirements are very different vs first floor. Current system has typical ductwork for both first floor and basement, only thing to control is cheap sheet metal dampers. House is fairly well insulated. Will replace all first floor windows soon. Basement has new glass block windows. Syracuse, NY, very cold winters / Fairly hot and humid summers. I seem to understand that a reasonable approach is to leave ductwork as is, shut basement dampers 75percent or so in winter to give some heat but less than total needed, and add some electric heat in basement in order to give temperature control (by separate thermostat). First, does that seem the best approach? Second, can the basement dampers be shut down completelly in cooling season, since basement temperature does not exceed 70 degrees even in summer? Will be happy to provide any other information to whoever might be interested in helping.