HELP! Boiler Pilot Light keeps going off

jdj5211

Have a very frustrating situation I’m trying to figure out. I have a 25 year old Lochinvar gas boiler in a home I just purchased.  It’s basically a pool heater. 

I started to have an issue where the house would get cold and I would go and find the pilot light turned off. I would re light it and it would light immediately with no issue. Sometimes it will stay lit for a few hours but other times it literally unlights after 15 mins.  

I replaced the thermocouple first but the issue still occurred. I then replaced the gas valve however that also didn’t fix the issue. The unit only has 2 security features that would trip the system. A rollout switch and one that’s on the damper that opens and closes to let the fumes out the chimney. Both have a button that would “pop” if it was tripped and neither are showing that it was tripped. If they were, I would have to reset the button before the unit would turn on again. Now here’s the weird part….

When the pilot light turns off I can hear the gas valve getting a signal to turn off (that click sound). What the heck would be sending that signal to turn the gas off?

I also took the lead wire off the gas valve and tested it. I saw that it was getting voltage through the wire which means the unit is sending the signal to the gas valve to turn back on, however it cant/won’t because the pilot is off.

I’m running out of ideas as to what the cause could be. Any ideas or help would be greatly appreciated!

John 

Jamie Hall

The thermocouple losing the heat from the pilot should turn off the gas valve -- and it sounds as though maybe that's happening. This is good. Reduces the chance for very loud noises and flying objects.

Now as to why the pilot goes out... how's your gas pressure? Has the entire unit been checked for proper gas pressure under all loads in the structure? Combustion adjusted?

Paul Formisano

Try cleaning out the pilot light orifice with a small needle.  I had the same issue, did the same steps as you did and finally noticed that the pilot was weak.  The pilot needs to completely surround the thermopile generator.  My millivolt system was only producing 300mv but when the pilot was cleaned up and increased I got 650mv.  There should be a pilot pressure adjustment screw on the gas valve that can be used to adjust the pilot in case you open the orifice too much when cleaning it out.

unclejohn

I think Paul is right but I would use my nitrogen tank to clean the pilot. Using a pin or needle might open up the orifice to much.