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Is this an oil or gas fired boiler?
If gas does it have a motorized vent damper?
You need to check. If you have one you will see a small electric motor attached to the side of the vent just above the boiler. I also need to know if you have a pilot that's lit all the time or electronic ignition
I need to know if the damper is open and if the pilot is lit
All time ...yes, motorized damper . Switched it to held open
There's no circulation