How good it the quality of a Goodman gas furnace? How many years can I expect it to last? How expensive is it to have serviced after the warranty is expired? How efficient is the Goodman furnace? Are the parts that usually require service easily accessible and parts easily found? Are the doors to the parts solid and closed?

Just had my furnace served they said I has a crack in my heat exchanger is there any warranty on this its about 10 years old