The preasure relief keeps going off when boiler runs. It has a new expansion tank and a good preasure relief valve.
I would suggest the thermostat is stuck and don't cut out the heating element.
Sounds like a defective aquastat. This device shuts down a hot water boiler at 190 degrees even if the house has not reached temp. Water circulates through the system until the aquastat says its time to refire again. This is only for a hot water boiler system, not steam. I think the stat is about $80.00. Check temp gauge and see if it overfires past 190 degrees. I would RECOMMEND You use a profesional company for repair as for water in excess of 107 degrees is very dangerous if something in the system should overheat and let water escape. Not a pro but I have a hot water system as well. Just past experience as a homeowner. Hope this helps You.
have you moved the thermostat at all, have a look under the boiler does it have 2 valves under neath it, turn them clockwise for a couple of minutes, then turn them back again, and see if it drops down. if that is not it you may have air in your radiators, bleed them and take a cloth and a bucket with you, and a towel of some sort, so when you bleed them any water that is spilt you can wipe up with.
