Our Gas furnace needed a part last night, it was blowing cold air. The repairman replaced the igniter... $400 bill... then he said we need a whole new furnace. We have a diamond 90 York that came with the house built in 1989. He mentioned we should get a Rheem. Anyone have experience with a Rheem and how much should we spend for a 2 BR bi level home 872 sq foot house. And how many BTU's should we get? Thank you! we live in Maryland and have central AC.