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[clydem]

I have noticed this year my boiler water temp seems to constantly creep up 10* to 15* over the high temp settings.  I started this year set at 180* and at 1 point I had a boil over. After that I reset the high temp to 170* and its been running fine except since then I've noticed the water temp creeps to 182/184* after the damper closes.  Could I have a problem with the aquastat or temp probe? The door gasket is fine, I eliminated that as the problem first thing.
Any suggestions?

[Pointblank]

Is the damper and solenoid operating smoothly? Maybe creosote build up on the damper keeping it from fully closing?

[clydem]

Is the damper and solenoid operating smoothly? Maybe creosote build up on the damper keeping it from fully closing?

Thanks for the reply,

I checked that first.  I replaced both the damper & solenoid this fall before heating season.
if the damper leaked the boiler would overfire. 
The boiler is 11yrs old and I think the problem might be with the calibration of the aquastat or the thermocouple.

[mlappin]

Thing to do is stick around till it hits the cut out and make sure the damper is actually closing, might have to watch it several times if a on and off problem. Do you have a way to compare the actual water temp to what the controller claims?

[RSI]

Does it have more smoke coming out of the chimney at idle than it used to? I doubt it is the probe from what you have said. Only way it would be the probe is if it is boiling at under 200 degrees.
The controller could be sticking though. Like mplappin said, watch it as it reaches the set point. If the damper is still getting power then the controller is probably bad. If it is shutting off then you probably have an air leak somewhere.

[clydem]

I have a X-300 temp monitor system and I know there is a 6/7* temp difference in the log from actual water temp.  The digital readout on the boiler increases 10/15* above the set point after the damper closes, this temp matches the actual temp from the dial temp gauge installed above the circ pump.  I realize this varies slightly with outdoor air temp.
A while back after the boilover someone from another site recommended I add a 1/2 ounce magnet to the outside bottom edge of the damper to make sure it does not stick open. This was done and works fine.

[atvalaska]

I got my temps  rite , I ended up with 165 & 5,outside temps and wind move around a lot here