My 820/20 runs at full pelt no matter hat the water flow. I have been told its not modulating ie not reducing gas as the water flow eases. Is this correct? The boiler heats fine but cuts out the pilot only after running a long hot bath. Why and are they related problems. The Timer no longer works and has been bypassed.

Gary Heiss, January 2005

I have the same problem. I've been living with it, but its getting worse - hot water is scalding hot and then the overheat shutdown operates. Did you find out if the problem was with the modulator? it seems to me that the modulator will only modulate if the DHW thermostat is operating.

Jeremy, April 2006