I can not replace the whole furnace due to limited budget and mostly attic access problems. So I need to find a heat exchanger that I can replace the cracked one with. York furnace model #P1HGD15N10001a (1980ish). Or can it be retrofitted with a newer heat exchanger. Is there a creativeway to do that?
Thank you,
Freezing near Detroit.

I am doing a project on the Tesla Roadster and I need help on how to find the heat transfer in the electric car. How can I calculate the heat transfer in the Tesla Roadster?

I am look for free text book that can be used in
my class on fluid mechanics