Hopefully, this will be a short post. I got a call to Midland today on a furnace where another contractor told the customer the heat exchanger was "pitted" and failing. When I arrived, the customer was in a tizzy and upset that he had to pay to have me come over because his furnace was an Amana. First of all, the furnace was a GUID model, an 80% with a stainless steel heat exchanger. I've installed and worked on hundreds these models nearly two decades and have yet to condemn one. They're pretty bulletproof, so naturally, I was skeptical.
Sure enough, I pulled off the draft inducer and there was some surface corrosion, but this doesn't mean the furnace is junk. A few scrapes with a screwdriver confirmed these were not an issue. What I did find was a mess of corroded metal in the collector box and the customer, now in hysterics, informed me that it was piled inside until the other contractor "cleaned" it out. I also saw a lot of sulfur inside same, but unless it's plugging the heat exchanger, there's not much concern either. What I do know is that it was running on propane and as we all know, propane is at a higher pressure than natural gas. It needs to be ten inches of water column as opposed to 3.5 inches with natural gas. I got about 6 inches and 180 degrees at the stack. The temperature should be higher; about 350 degrees to be exact and with single wall vent, this will eat it up in short order.
This is likely the metal clogging the collector plate due to the condensation and the "pitting" present in the heat exchanger. I told the customer he needed maintenance, but to no avail.
When you hire someone like me for a second opinion, what's the sense of arguing with me? I do this for a living and have worked on furnaces for 26 years. I don't claim to know much about embalming, or even carpet cleaning, so I call in the pros to do that specific job. Maranatha!