Munchkin 140 makes strange noises when it is 0 Farenheit or less outside

DABegley

I have a munchkin 140 boiler that makes strange noises when it is below 0

outside. I think this is due to improper timing between the

circulators and the boiler. I have a radiant heating system with three

zones. When one zone calls for heat the zone circulator turns on. If

the circulating water temp is not high enough the main circulator turns

on, a few seconds later the blower turns on followed by the gas valve

opening and the boiler flame igniting. The boiler commonly shuts off the

gas then reignites. When the circulating water temp reaches the set

point the zone circulator continues to run, the main circulator turns

off, a few seconds later the gas valve shuts extinguishing the burner

flame and the blower goes into the purge cycle. When the circulating

temp fall too far the cycle starts again from when the main circulator

activates. The system has an outside temperature detector which raises

the circulating water temp the lower the outside temp is. When the temp

outside is below zero the system makes some grinding/knocking noises

just before the boiler flame goes out (after the main circulator shuts

off). I believe this is because the boiler temp shoots up in those

couple seconds between when the main circulator shuts off and the flame

shuts off. If the circulating temp is low enough the rise in temp isn't

enough to make noises but if the circulating temp is high enough the

boiler temp gets up very high and causes the noises. Does this sound

like a valid theory and should I locate a technician to adjust this?

Thanks.  The boiler temp is set at 180 with a variance of 30 (the factory settings), is that too high?  One of the zones has an engineered wood floor, the other two are vinyl or carpet.  The highest water temp I have seen flowing through the pipes is 165, based on the temp gage on the water outflow pipe about a foot from the boiler.  If I look inside the boiler after the noises are made and the boiler has turned off the temp on the control panel reads 200 or more.  I could set the temp to 170 or lower which could reduce the temp overshoot.  Thanks again.

DABegley

Munchkin 140 makes strange noises when it is 0 Farenheit or less outside

Forgot to describe the noises, they are a banging/grinding sound.  Not horribly loud but loud enough to hear on the first floor.