What I learned this week...


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Old 09-09-18, 01:40 PM
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Exclamation What I learned this week...

My 3 yr.-old Rhreem 50 gal. gas unit failed to light after repeated attempts. I got their tech support to send me a new gas control unit, and ended up having my local plumber install it, both of us thinking it would solve the problem. Nope. Pilot lit right up, but the burner would not light. Unable to think of any other solution, he pulled the pilot assembly out, and lo and behold, the flame sensor was coated with a fine, white ash-like material. This, he explained, was preventing the electronics to tell the burner to light. A little sanding to expose bare metal was all it took to get the burner to like right up. All is well now.

Multiple calls to Rheem failed to reveal this component as the possible source of my problem, and I count it as sheer luck that my plumber had enough experience with newer heaters to suspect that this part might be the cause of the problem. I called Rheem back to tell them this tale, and they agreed to send me the affected parts, just in case it should happen again. I asked that the nice lady make a note of my experience and share it at their next troubleshooting meeting (which, I'm sure, they hold frequently )

Has anyone else had this experience, and were you able to figure it out on your own? If I had replaced the gas control unit myself (turns out I could have), I would have been at a complete loss as to what to do next when it failed to like the burner. Some fun....
 
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Old 09-09-18, 02:50 PM
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Have to say...that's about the first thing I would check on a newer unit, or an older one for that matter. Make sure the sensor is clean and shiny.
 
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Old 09-09-18, 03:33 PM
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That is an unusual problem as that flame sensor if it was so coated..... should have not allowed the pilot to remain lit.
 
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Old 09-09-18, 04:30 PM
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Oh, Yeah...I missed that. I was thinking even after a new part the pilot wouldn't stay lit. Could it be the tiny voltage is that specific? Enough to keep the pilot lit, but not enough for the control to open?
 
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Old 09-09-18, 05:18 PM
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According to my plumber, yes, it was the minute voltage (or, the resistance to it) that kept the signal from allowing the burner to light. And yeah, Gunguy45, I would have too, had I know what I know now. In the last few days I have gotten an almost complete education on water heaters. The truth is, your average homeowner is at the complete mercy of whoever comes to their aid when they have water heater problems. I've repaired and troubleshot many things around and in my house, but this one left me feeling at a near complete loss. At least now I feel like I have a fighting chance the next time something goes wrong.
 
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Old 09-10-18, 06:32 AM
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I had a comparable experience (with a gas space heater as opposed to a water heater).

The moral of the story -- The manufacturer needs to have a more comprehensive textbook, or playbook, of answers.

In my case I conclude that the thermocouple connection to the gas control valve was loose so the tiny current did not flow at all let alone be of the correct value.

The OP might have had the same loose connection as a secondary problem but once the sensor was removed to be cleaned and inspected and reinstalled, the connection was retightened so the possibility the connection was loose went unnoticed.

For me, the heater was new out of the box. I called both the seller (a big box store) and the manufacturer. Neither was able to help me. Ultimately I returned the heater to the seller for an exchange.

When I installed the heater again it had the same symptom -- pilot would not stay lit. This time I thought about verifying the tiny voltage from the thermocouple and I found the loose connection that I immediately concluded that the first heater also had that problem. When I found and tightened up the connection (i skipped trying to measure the voltage) the heater worked perfectly.

I might add that this screw on thermocouple end was one of those few funny or maddening or frustrating screw connections that, no matter how hard you tightened it, it could be loosened with somewhat less force and in this case not matter what I did within reason I could unscrew it with my fingers. No, I never used, and never recommend that anyone else use, stupendous force to tighten it.

The score or aftermath or damages left behind: A small cut on my thumb from the process of returning one heater and getting the exchange. The seller was left with dealing with the used returned/exchanged heater (it ran for a few minutes after a lengthy session trying to get it to start and then went dead for good and therefore is now considered used). The manufacturer would probably not have found a new problem to add to their textbook unless the store returned the heater to the manufacture (as opposed to resell it as a floor sample) and also the manufacturer examined it carefully.

Having a good amount of electrical experience under my belt from an earlier lifetime, yes, I muttered to myself, "Duh!".
 

Last edited by AllanJ; 09-10-18 at 06:55 AM.
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Old 09-10-18, 11:26 AM
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Interesting story. Just another instance of a product that otherwise would function fine IF everything in were designed, engineered and manufactured properly. One little connection poorly made and/or implemented and we (or those we hire) are off to the races troubleshooting. I am now at the point, after multiple such episodes with all kinds of products, of assuming that nothing will work correctly out of the box, or if it does, it will eventually fail. Sure, things wear out, parts corrode, connections fail. I'd wager Rheem has had this very issue crop up for owners multiple times, yet the sensor and its function are nowhere to be found in any of the troubleshooting guides offered, either in print or online. Of course, I found an entire video that showed exactly what my plumber did on YouTube, but only because I now knew what to look for. Your story of your heater is just another example of how buyers and homeowners have been left to the mercy of the manufacturers, who nowadays worry more about answering to boards of directors with P&L statements than they do the quality and durability of their products. Final thought: when I asked my plumber what water heater he would put in his house, he paused, thought a minute, looked at me and said: "I don't know." 'Nuff said.
 
 

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