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heat exchanger failure

Neal Lewis

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Attached are pics of a Rheem Imperial Drum 90 furnace heat exchanger. This unit is from the 90's and from what I hear there have many problems with this heat exchanger. The unit is sealed and there isn't even a glimpse of the HX. Obviously, the drum was overheated big time.

The furnace had been replaced by a HVAC contractor last year after the owner had repeatedly had the unit "repaired" by the local gas company under their warranty program "Worry Free", which BTW doesn't cover the HX. The gas tech replaced circuit boards many times because the furnace shut down. They never even dissasembled the unit the to check under the hood!

The owner's elderly mother died of other causes before this was replaced, but had some strange, undiagnosed bloating. The caretaker had collapsed in the house, but it was attributed to dieting! The owner did have CO detectors.

BTW, the Rheem Criterion? 80% furnace in the attic had the characteristic cracked plastic inducer fan housing and the flue was disconnected from the inducer housing because the flange was broken off. The hot surface igniter had just been replaced, and the furnace had just been given the AOK!

I'm not sure what my point is, but the owner was thankful and now even more peeved at the furnace guys.

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icon_speech_duh.gifGuess Gas Co. did not have a CO testing meter.

Have the CO alarm tested with CO gas then have a CPSC report filed when it fails. If enough of these high level alarms get condemned maybe UL will go back to the original standard.

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I was there for the first time inspecting for a relocation company. I guess the owner gave up on the gas company to fix the problem and called a HVAC contractor. The owner had kept the HX and other parts on hand some some reason, even though the furnace was replaced last year. He said he was glad he kept them; he could use the old inducer fan to replace the cracked, defective one. Maybe he wanted to save some money. The house was only 5800 square feet! Go figure.

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Okay, now I understand. Any scorching on the cabinet of that furnace that the other guy should have seen or did it appear fine outwardly?

MechAcc, CO detectors aside, if the unit was burning clean with a good 10:1 air/fuel ratio this probably would not have affected anyone anyway and the sickness might have been just that - sickness.

I once found a furnace with a hole the size of a Kennedy half-dollar piece in the back of the heat exchanger. The hole was clearly visible by shining my light into the combustion chamber. The furnace was pretty old but looked like it had been burning pretty cleanly. I took out my Monoxir and used it to check for CO in the home. Nadda. Thinking it was the Monoxir, I went to my vehicle and got my backup Monoxir and re-tested the home. Nadda.

While I was checking out the furnace, the client had gone off with the realtor and listing agent to another part of the finished basement to make some measurements.

I called the client back into the utility room and informed him that there was a 50-cent piece sized hole in the heat exchanger. Well, this was one of those inspections where the listing agent just happened to show up and followed the client and his agent around chatting with the buyer's agent in the background, all the while keeping a careful eye on the inspection, and every once in a while one or the other of them would offer a comment or two of codespeak to try and get me to present things to the client the way that they wanted them presented. I'd been ignoring their signals for about an hour up to that point and was secretly enjoying the way they were squirming in the background.

Anyway, when I informed the client of the hole, the listing agent went a little nuts. "A hole?!! What are you talking about? There can't be a hole in that heat exchanger! If there were, everyone in the house would have been dead from carbon-monoxide poisoning! This furnace was just serviced and the heating guy never said anything about a hole! Where the hell did you get your training, anyway?

I'm an ex-cop. I just gave him my best perp stare and quietly asked, "Why do you want to know?" "Because any home inspector who knew what he was talking about would never make such a stupid observation. That's why," came the defiant reply and an equally flat stare. I never took my eyes off the listing agent. Just kept my eyes locked on his, and handed my Maglite to the client and said, "Look straight in past that flame to the back of the second chamber from the left and tell me what you see," and kept staring at the listing agent. By now the room had gotten realllly still, because he obviously didn't intend to be stared down by a mere home inspector and I never let a perp gain control of an interview so I wasn't about to drop mine.

The client obediently took my Maglite, shone it into the furnace, caught his breath and then said, "Holy Sh*t! There's a hole in there big enough to put two fingers into!" The listing agent's gaze began to waver and I could see the first little bit of self-doubt creeping into his eyes. "You should probably know," I said, "That when the air-flow mixture on a furnace is adjusted perfectly, as this one is, that a gas flame doesn't produce any carbon-monoxide. It produces carbon-dioxide, water and nitrogen - just about the same thing that you're exhaling right now. Hole or not, if that furnace is burning clean, nobody's going to get sick from it. I'd say that you're the one who needs to get a little more training. What do you think?"

That did it, he dropped his stare and then tried to stammer an apology. I came back with something Walt Jowers had once shared on the ASHI forum years ago, "There are only two people on this team right now. That's myself and my client. You, the both of you, are on the bench and for the past hour have been trying to get into the game. Why don't you both go have a seat now and let me finish this inspection for my client? When I'm done, (to the buyer's agent) you can have him back and he'll be your client again."

Both of them turned beet red. The listing agent lifted his hand, pointed a finger at me and was about to say something and then stopped and said, "Ah, forget it," waved his hand dismissively, and they both walked off. There was this long pregnant pause and then the client started to giggle nervously. I just winked at him, went about jotting down my observations and then we continued with the remainder of the inspection undisturbed.

That had been a referral from a previous client and was about 4 - 5 years ago. The client walked away from that house. I did another one for him about two weeks after that which he bought. The buyer's agent sat in the living room and read a newspaper during that inspection. Neither one of those agents has ever referred a client to me since and that's fine with me. When I've inspected homes they've listed, they've stayed away and have never tried to argue about anything written in my reports.

So what's the point of my egregious attempt to create thread drift? I guess it would be to say that absent outward indicators on that cabinet, an odd reaction from the flame when the blower comes on, abnormal combustion reading registering on a test device or some type of other inspection more invasive than a look at the HX with a mirror oil sprayed into the HX or smoke candles - there's probably no way anyone would have spotted this anyway. It's one of those latent defects that can be there all the time and despite our best efforts and use of our technology it can easily be missed.

These are excellent photos to use for that part of a training course where you bring the inspection student to the sobering realization that this is still a very seat-of-the-pants profession and absent experience they are really hanging themselves out there like a piñata.

Thanks for sharing Neil.



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