why do the heat exchangers crack in the janitrol gmp075-03?
One possibility is the heater is not running to the end of its cycle when turned off. It should very often be heard that the fan is running after the burner shuts down to cool it dowm. Latent heat will cause the damage mentioned.It should not be turned off via the power switch to stop its use as the fan will not run.
You need to contact goodman (thats who made this unit) and give them the MN# and SN# to verify that the heat exchanger is or is not under warranty. The part may be but the labor is not. Heat, lack of air flow, overheating and poor design in some cases. I have seen where people show the home owner the supposed crack which is really a front plate that is bad. and thats all that needs replacing. I cant remember if this model has the plate or not. But reach out to goodman and see if its still covered. Then your going to need to find a authorized dealer who will give you the part so long as you have the old one with you. Johnstone supply may do it for you.
Many furnaces have had problems with heat exchangers, over the years. The number one reason for failed heat exchangers is oversizing of the furnace. Oversizing causes overheating and when metal is overheated and then cooled, it is kind of like bending a paper clip, sooner or later it is going to break. Failure to change your filter will also yield the same result. Janitrol was a lower end furnace and had many challenges with quality but they certainly were not alone when it came to quality issues.
