We had a diagnostic on Monday that ended up falling outside the norm. Heater failures tend to be common and usually consistent, but sometimes they'll make us work for a diagnoses.
Client had a 3.5 yr old MasterTemp 400. Has been running fine for years. No repairs needed. Recently reported it was not holding temp. We sent a tech to diagnose and the report was that the heater would initiate and fire as expected, but after roughly 60 seconds, would begin to 'sputter'. A better description would be the flame would audibly put out, only to reignite 0.5-1 second later, and repeat rapidly. After doing this 5-7 times, the heater would then exhibit signs of boiling in the manifold.
Couple quick points of clarity: the flame was unquestionably being extinguished, and then reigniting rapidly. It was not any more violent than when the heater ignites normally. Though as you'd expect, it was more violent in general because it was doing this in rapid succession. And second, the ruckus in the manifold always followed the combustion issue. Never before.
To start, we softly ruled out an issue with all items within manifold since it was always secondary. Ignitor was fine. Blower orifices clear. ICM looked good. No water in combustion chamber. Wiring intact.
Began to suspect either the gas supply was tainted with water or air, or we had a hole in the flame holder. Weren't looking forward to removing the blower to check and last time we found a hole in the flame holder, we had what you'd expect - a much more violent ignition of the escaped fuel. That heater scared us silly - natural gas bombs are rude.
But that was not the behavior this time.
Had the tech shut it down until we could reconvene.
Fast forward to yesterday and I went out myself to dig deeper. Fired heater up to monitor the behavior, figuring I may take note of queues he missed. Heater initiated and ran for about 30 seconds and threw a classic E05. I was immediately annoyed and figured it was a result of the seizures from the day before and reset it with the same result. Monitored the sensor readout and instant 40. Annoyance grew, but chalked it up to coincidence and replaced to get back on track for what I came to do - the diagnostic.
New SFS: heater fired and ran as expected. I stood waiting for it to stumble after the first few minutes. Except it didn't.
I was highly skeptical the issue was resolved so I stayed and watched - for over 30 minutes. No issue returned.
At this point, I'm still skeptical the issue has been solved. When an SFS reads a temp the PCB doesn't like, the heater enters shut down and throws a code. It should not extinguish flame and then immediately reignite in rapid sequence. I'm not convinced the SFS could have been the issue. But I'm open to the possibility under extenuating circumstances. I've done this enough to know as soon as you think you're an expert, the universe will prove you're not.
All that said, I'm more of the opinion it may have been a gas supply issue now resolved, or an issue that will reappear again when circumstances are right. Perhaps after extended duty.
As of now - 16 hours later, a recurrence has not been reported. So we assume it's still running.
I'm open to any spaghetti you'd like to throw on the wall. At this point I have a few globs of my own waiting to fall.
Client had a 3.5 yr old MasterTemp 400. Has been running fine for years. No repairs needed. Recently reported it was not holding temp. We sent a tech to diagnose and the report was that the heater would initiate and fire as expected, but after roughly 60 seconds, would begin to 'sputter'. A better description would be the flame would audibly put out, only to reignite 0.5-1 second later, and repeat rapidly. After doing this 5-7 times, the heater would then exhibit signs of boiling in the manifold.
Couple quick points of clarity: the flame was unquestionably being extinguished, and then reigniting rapidly. It was not any more violent than when the heater ignites normally. Though as you'd expect, it was more violent in general because it was doing this in rapid succession. And second, the ruckus in the manifold always followed the combustion issue. Never before.
To start, we softly ruled out an issue with all items within manifold since it was always secondary. Ignitor was fine. Blower orifices clear. ICM looked good. No water in combustion chamber. Wiring intact.
Began to suspect either the gas supply was tainted with water or air, or we had a hole in the flame holder. Weren't looking forward to removing the blower to check and last time we found a hole in the flame holder, we had what you'd expect - a much more violent ignition of the escaped fuel. That heater scared us silly - natural gas bombs are rude.
But that was not the behavior this time.
Had the tech shut it down until we could reconvene.
Fast forward to yesterday and I went out myself to dig deeper. Fired heater up to monitor the behavior, figuring I may take note of queues he missed. Heater initiated and ran for about 30 seconds and threw a classic E05. I was immediately annoyed and figured it was a result of the seizures from the day before and reset it with the same result. Monitored the sensor readout and instant 40. Annoyance grew, but chalked it up to coincidence and replaced to get back on track for what I came to do - the diagnostic.
New SFS: heater fired and ran as expected. I stood waiting for it to stumble after the first few minutes. Except it didn't.
I was highly skeptical the issue was resolved so I stayed and watched - for over 30 minutes. No issue returned.
At this point, I'm still skeptical the issue has been solved. When an SFS reads a temp the PCB doesn't like, the heater enters shut down and throws a code. It should not extinguish flame and then immediately reignite in rapid sequence. I'm not convinced the SFS could have been the issue. But I'm open to the possibility under extenuating circumstances. I've done this enough to know as soon as you think you're an expert, the universe will prove you're not.
All that said, I'm more of the opinion it may have been a gas supply issue now resolved, or an issue that will reappear again when circumstances are right. Perhaps after extended duty.
As of now - 16 hours later, a recurrence has not been reported. So we assume it's still running.
I'm open to any spaghetti you'd like to throw on the wall. At this point I have a few globs of my own waiting to fall.
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