Boiler will not run

Eileen Olive

Have a 30-year old Weil Mclain CGi boiler (gas, hot water) that will not run when called by t-stat. It has water, 12#, the transformer is good, at the t-stat anyway, the pilot is burning, and I don't get it. It ran fine last season. No changes or alterations at all. Now she won't fire. Any ideas? Please my head is spinning.

Brad White_191

Thermocouple

or gas valve would be the next things on my list. Pro-time at that point.

oil-2-4-6-gas

do you have batteries in the stat? --Energizer or Duracell only if you do --many of todays thermostats have batteries to make the switch

JB_8

spill switch

Spill switch on? Check to see if you have a blocked flue pipe maybe a dead bird or other blockage?

Eileen Olive

Thanks

The vent pipe is fine, no spill switch, and the wather heater is tied in to the same pipe. The stat has no batteries. I "thought," and I know the potential danger of that word, that the pilot would be out if the thermocupler went bad. If the circulator died, or seized, would the boiler still fire? I am grasping at straws at this point.

Unknown

EJ you are correct if the pilot is lit

the thermocouple is okay. Do you have 24 volts to the gas valve? If so and the valve does not open there is a good chance the valve is bad or it could be a broken ground back to the transformer.

Yes the boiler will fire and the circulator could be bad and not run. If that is the case it would cycle on limit. Do you see a burner flame inside the boiler other than the pilot?

Timco

I'd check the controller by manually pushing the contacts together. if it fires right up, new controller time. That tells the boiler to fire and turns the pump on.

Tim

tim smith

Could be bad flame roll out switch. Located right where burners

go into combustion chamber on burner enclosure cover plate. Has 2 wires to it and has a ceramic holder and small fuse link. If this is open then you could have restriction in heat x or burners are corroded out. We find bad burners quite often on this vintage of boiler. Just a thought. Tim

oil-2-4-6-gas

there are many things that could be going on for DIY stick with the thermostat and call someone in for anything else -take the stat off of the sub-base jump r terminal to w terminal go downstairs see what happens if nothing then you need to call someone in