I have a two story house with separate systems for each floor. The furnace on my second floor split system stopped producing heat. The tech from the company who installed unit said it was a recalled furnace that he couldn't work on and gave me an estimate to replace the furnace. It turns out he was wrong about the unit, it was a different model that was recalled. The second repairman said it was a cracked heat exchanger and he turned off the gas. He told me I could have just the furnace replaced. The third company told me I should replace both furnace and ac, even though the ac is still working. The units were installed in 1991.
What questions should I be asking the contractors? Is it unwise to just replace the furnace and wait until the ac breaks to replace it?
The furnace is a Bard ISG060D036A. The ac is Tempstar CA5024. My upstairs is about 1,000 square feet.
The first contractor bid: (the tech who was wrong about recall model)
Just replace furnace with Ameristar M801P040AU24AA; Warranty on heat exchanger 20 years, Parts 10 years, Labor 1 year, no permit.
The second repairman (the guy who found the crack in heat exchanger)
Not a written bid but a phone call saying I could just replace the furnace with either a Rheem 50,000 btu or Goodman 60,000 btu, no permit.
He says replace both furnace and ac
Furnace: Amana AMH80403AX CE30D44140
His bid includes permit, new overflow pan, 2 year labor warranty, 10 year limited parts warranty (mfg); LT compressor(mfg), 10 year limited evap coil warranty(mfg); LT heat exchanger warranty(mfg); 2 year limited labor warranty (total); 1 year service agreement.
I have one more contractor to call, but think I need to be better informed, and ask better questions. The third contractor told me the Ameristar furnace recommended by the first contractor is a "builders model." What is the significance of that? Because I'm getting different opinions on whether to replace the furnace alone or both furnace and ac I can't really compare apples to apples.