Ten days ago, my girlfriend had a 90min power outage at her house. It became chilly that evening and when the boiler apparently hadn't done its job, I went to investigate. I found the pilot out and, as soon as I re-lit, it immediately went out again. I then began boiler troubleshooting 101...
The system: Utica PEG150 (older model) natural gas steam boiler. Battery-powered thermostat makes a connection between the hot-side of a 24v transformer and the safety controls (Honeywell Pressuretrol 169H, then to an M&M No. 2 LWCO) before reaching a Honeywell VS820A 1245 valve. Wiring on the valve is as follows: 24v in from LWCO to TH/PP terminal; and TH (upper left) terminal out to the transformer ground.
Troubleshooting performed thus far: Determined that the Powerpile was faulty (would not generate more than 510mv) so, replaced with new Q313A. Powerpile now generates 720mv when lit (disconnected from valve and holding the pilot valve open for about five minutes.)
With Powerpile disconnected and control wiring NOT connected, I read resistance on the valve as follows: between PP and TH/PP, 2.1 ohms; and between TH/PP and where the red, factory wire enters the power unit, 10.2 ohms.
With the thermostat calling for heat, I have 24.6v present at the valve. Proactively, I've already replaced the wiring between the thermostat/transformer and boiler cut-off switch (with new 18/2.)
With Powerpile connected and control wiring NOT connected, pilot stays lit and I read 620mv between the PP and TH/PP terminals. Same scenario but with a jumper between TH and TH/PP, I read 255mv between PP and TH/PP.
With both Powerpile and control wiring connected -but no call for heat- pilot stays lit and I read 565mv between PP and TH/PP. Same scenario but with a jumper between TH and TH/PP, I read 253mv between PP and TH/PP.
With both Powerpile and control wiring connected -but WITH a call for heat- the pilot immediately goes out and the valve emits a buzzing sound. I have not yet attempted to re-light the pilot while the system is in this condition.
Respectfully, I seek some assistance: assuming I've taken my readings correctly, what do they tell you? Is the buzzing an obvious indicator, regardless of the readings? Should I attempt to re-light, after the pilot goes out (as described above)? Are there other tests/readings needed?
Thanks in advance.
The system: Utica PEG150 (older model) natural gas steam boiler. Battery-powered thermostat makes a connection between the hot-side of a 24v transformer and the safety controls (Honeywell Pressuretrol 169H, then to an M&M No. 2 LWCO) before reaching a Honeywell VS820A 1245 valve. Wiring on the valve is as follows: 24v in from LWCO to TH/PP terminal; and TH (upper left) terminal out to the transformer ground.
Troubleshooting performed thus far: Determined that the Powerpile was faulty (would not generate more than 510mv) so, replaced with new Q313A. Powerpile now generates 720mv when lit (disconnected from valve and holding the pilot valve open for about five minutes.)
With Powerpile disconnected and control wiring NOT connected, I read resistance on the valve as follows: between PP and TH/PP, 2.1 ohms; and between TH/PP and where the red, factory wire enters the power unit, 10.2 ohms.
With the thermostat calling for heat, I have 24.6v present at the valve. Proactively, I've already replaced the wiring between the thermostat/transformer and boiler cut-off switch (with new 18/2.)
With Powerpile connected and control wiring NOT connected, pilot stays lit and I read 620mv between the PP and TH/PP terminals. Same scenario but with a jumper between TH and TH/PP, I read 255mv between PP and TH/PP.
With both Powerpile and control wiring connected -but no call for heat- pilot stays lit and I read 565mv between PP and TH/PP. Same scenario but with a jumper between TH and TH/PP, I read 253mv between PP and TH/PP.
With both Powerpile and control wiring connected -but WITH a call for heat- the pilot immediately goes out and the valve emits a buzzing sound. I have not yet attempted to re-light the pilot while the system is in this condition.
Respectfully, I seek some assistance: assuming I've taken my readings correctly, what do they tell you? Is the buzzing an obvious indicator, regardless of the readings? Should I attempt to re-light, after the pilot goes out (as described above)? Are there other tests/readings needed?
Thanks in advance.