On 1/15/2015 3:01 PM, TomR wrote:


I was definitely wondering what may be causing the short cycling where his
heater keeps cuttin gout and then restarting before getting the radiators
hot. I don't know if a bad circulator pump could cause that or if something
else is being detected by a sensor of some type that keeps telling the
heater to stop and then re-start.


Few possible things.

There is a high limit switch that will cut the burner at a pre-set
temperature. That would make the boiler cycle more if it is set too low
or defective. If the circulator is not moving the water to the rest of
the house it will shut down the burner. If the boiler cycles for just a
couple of seconds, I'd first feelt he pipes and see if the water is
moving. If not, replace the pump. If yes, check the limit switches.

There are other potential problems but not enough information to
discuss. Since the boiler is 2 years old, I have to assume it worked OK
last year. If so, that removes speculation about the size of the
boiler. It is probably smaller in output, but that is because it is
more efficient. If the old boiler was 60% and dumping 40% up the stack,
an 85% boiler does not have to be as big.