Boiler stopped firing overnight without indication of error

[Bunny Laroche]

Hello,

I feel somewhat terrible as I only post here when we experience boiler troubles.

Well, when I woke up this morning the temperature in the house dropped to ~60 degrees. The rads were cold to the touch and although the boiler was powered on and appeared normal without any signs of problem, it was not firing when there was a definite call and need for heat.

My GF started to do system checks and observed the following with our Westinghouse 80K BTU boiler:

- the boiler's main display screen displayed no obvious signs of trouble. There were no err codes displayed, and everything appeared normal except the FAN and GAS icons were not present, which makes sense because the boiler was not firing
- the outdoor temperature reported by boiler was correctly reported at ~3 degrees
- voltage reading of the ODS leads: ~4.75VDC, which my GF said should be about right for the temperature sensed outside
- in the boiler's "installer mode" menu, the 1:EH (error history) value was: E0.11, and the manual shows that the default is E0.00. But, when we selected the 1:EH option (pressing the large round dial knob with the Enter symbol) no additional error information was conveyed. We weren't absolutely sure, however, that there might be something more we need to do to access further error history information from this option's menu.
- the TACO valve controller appeared to be operating normally as did the supply and return pumps. The valves were open and the pumps were working because the two zone thermostats were calling for heat.

So, since nothing appeared obviously wrong, my GF powered the boiler off, using the boiler's power switch located on the control board behind the (removed) cover. She left the power off for ~10-15 seconds before turning it back on. The boiler appeared to perform a normal start up procedure, afterwhich we turned the two zone's thermostats back on, one at a time. With a call for heat activating the TACO controller once more, the zone valve opened and two pumps began circulating as expected, and ~5-10 seconds later the boiler fan came on and proceeded to fire up. That was two hours ago and the boiler continues to operate normally with the room temperature rising slowly but steadily.

Our primary concern then, is what might have caused the boiler to stop operating (firing) during the wee hours of the morning when there was a definite call and need for heat? And can we expect it to occur again/often?

My GF also captured these results from a combustion analyser probe inserted into the flue after a 1-2 minute stabilization period. Although the results do not suggest anything wrong, I thought it best to include them for thoroughness.

Testo 310's bottom menu readings:
CO: 15ppm
Eff. : 98.1%
T: 14°C
EXA: 30.9%
CO2: 8.68%

Testo 310's top menu readings:
O2: 5.4%
T: 31.2°C
CO: 3ppm
uCO: 20ppm

 

[Jadnashua]

Can you monitor the system water pressure?

You'd have to read the system manual to see what interlocks there are, and then try to test them. Not familiar with that boiler. Usually, if a boiler goes into lockout, there's some error indication. It sounds like it had trouble with one of those interlocks (maybe justifiably), and after trying for the prescribed cycles, gave up and stopped (lockup). When that happens, if there's not a reset button, a power-up restart often clears it, but again, usually it indicates the error.

Common interlocks are: low pressure, high pressure, failed to fire (flame sensor), overheat, and, if it's a closed combustion unit, sensors to verify that there's no obstruction in either the intake air or the exhaust.

 

[Sponsor]

 

[Bunny Laroche]

Can you monitor the system water pressure?

Yes my GF installed a temperature/water pressure gauges on the supply and return pipes close to the boiler. When she went downstairs to investigate yesterday she said system pressure was at city pressure, so ~12psi, which is what I think should be expected for a cold primary loop.

Usually, if a boiler goes into lockout, there's some error indication

We fully expected to observe some sort of error displayed on the boiler's output screen, but all appeared normal. All except the ER0.11 error history indicator that the manual describes default as ER0.00. But navigation in that menu option did not seem to reveal any additional details.

The boiler ran all day without hiccup, so I hope it was just an odd occurrence when the boiler's controller perhaps got hung up. But we remain wary.

When we woke this morning at ~6AM, although the boiler was still operating and the radiators felt moderately warm, the ambient room temperature had dropped again to ~60 degrees (like it did the night before when the boiler was fired). The boiler was fired but it operating CH was only 100 degrees, with its target CH set to 125 degrees. This is the setting we have discovered is ideal at the current outdoor temperature to allow the boiler to run almost non-stop while maintaining our near ideal indoor ambient temperature of 72 degrees.

However, this behavior is not exactly new. We have noticed that the boiler sometimes runs at a much lower operating CH temperature than what its target CH is set for, allowing the room temperature to drop several degrees before it seems to pick up hours later bring the temperature back up by increasing its operating CH. But we have never noticed that the temperature was allowed to drop so low in past instances of this phenomena before the boiler seems to recover.

Today, however, rather than wait and allow the boiler to ramp back up to its target CH and eventually bring the room temperature back up to 72 degrees, as have have tended to do in the past, we instead, turned our thermostats' call for heat off, let the boiler turn off its current firing cycle, and then turned the thermostats' call for heat back on. After the boiler responded by re-firing, it only took it about 7 minutes for it to heat up to its target CH of 125 degrees from its previous operating CH of ~100 degrees when it cycled off.

I wonder if posting our boiler's current settings in Installer Mode might help to identify the culprit responsible for this set-back-type behavior?

 

[Jac04]

You have only experienced the problem during very cold outdoor temps, right? If so, don't forget to check out the gas supply side of things. Sorry I don't have more to offer. I just know that I had all sorts of gas supply problems at one time and they always got a lot worse when it was very cold outside. I'm on propane, so your situation might be different.

 

[NY_Rob]

I haven't had an error code thrown on my HTP UFT-80W yet, but going by the manual it seems like once you're in installer mode, turn the dial to 1:EH, press enter
Once on E0:00 press enter again to display first stored error code
Press return to go back up one step
Turn dial to go to next error history entry, press enter to display error code, press return to go back up one step.
Repeat as needed...

Something to try anyway.....
You could also call HTP support (same ppl that support the Westinghouse boiler) 800-323-9651, they should be able to walk you through retrieving the stored error codes.