Paws N Suds Pet Grooming Rooftop Furnace Repair

Hey guys! So my rooftop furnace is in need of an expensive repair. We need a new heat exchanger. My unit has 2 and one was already replaced. So with the replacement of this second one I will have basically fixed everything in the unit. I have already made several repairs this year to it. All though the unit is older it is still repairable and a much more economical alternative financially. The repair will cost $3000. This has come up obviously unexpectedly and I have to do this quickly as I can't work without heat. As of right now it works intermittently and has to be reset often to make it work. My landlord does not help with these things unfortunately. This is a difficult expense to a small business. Any help would be amazing!