Have a 1990 Carrier 100,000 btu Oil furnace that's been serviced annually. The tech from our oil company has told us the heat exchanger is cracked and the furnace needs to be replaced. I found out that Carrier's warranty is actually 20 years on the heat exchanger part (no labor) so this part could be replaced under warranty but we'd still have a sizable labor installation fee. Should we invest money in repairing this or look for a newer furnace? In looking through this forum and other sites, it appears the one Canadian company now actually manufacturers Carrier Lenox and Trane furnances. Willamson and Thermopride are brands our oil dealer carriers - they are pushing Williamson over Thermopride (claim they can not get parts for Thermopride). Appreciate any recommendations on repair or new - and recommendations on Carrier - Willamson - Thermopride - American Standard.