Propane boiler shutting down prematurely

[layoric]

I have a coal boiler and a propane boiler. The propane boiler can be isolated, and it is currently (just runng lp). Periodically, the propane boiler will not fire, even when called for heat by a thermostat. The pump will run, zones open, but no flame. The damper will also remain open. This points to a flue problem, but there's no blockage. The liner is in chimney and clear. It is the only appliance on the chimney. Hitting the reset at the damper starts it up to fire again. Sometimes for hours, others for a few minutes.

I thought this was a flame rollout switch failing, but the manufacturer says it's a blockage somewhere. Could this be the switch anyway? Perhaps it's the propane vent on the tank outside that's clogging, and needs replacement?

Just don't know who to call, propane svc or hvac. If it IS the switch, I can just replace that. So what's going on?

 

[STIHLY DAN]

If your reset switch is at the damper in the flue above the boiler, I would replace that. If it is a condensing boiler, thats a whole different ball game.

 

[layoric]

If your reset switch is at the damper in the flue above the boiler, I would replace that. If it is a condensing boiler, thats a whole different ball game.

Turns out the damper was installed to far up from the boiler. Lowered the damper, rollout switch no longer trips. Standard boiler, not condensing type.