I have a gas boiler that from a cold start (first calls for heat) it will fire correctly, circulator will start running, and the burners stay lit until the set temp is reached. When the burners shut down the circulator will continue to run for several minutes. What I have noticed however, is that if it is really cold outside (usually at night) that the initial cycle will run but then the boiler apparently calls for the burners to fire again. They fire up correctly and then there is a click and they shut down. Five minutes later they fire again, another click and they once again shut down. This repeats several times. The circualtor continues to run during all of this.

I had a local heat and A/C guy look at it and he could find nothing wrong. He said sometimes parts have to fail completely before the fault can be found. My concern is that this seems to be adding $$$ to my gas bill.

Anybody have any ideas?

I also figured out that I have a Honeywell Type L8148E Aquastat relay, and a Taco cartridge type circulator 007-F5. I have 7 radiant baseboard heaters upstairs and 3 downstairs. Most of them are around 8' long.

Boiler info:

CAC / BDP
Series: PWB - 4D
Boiler Model No: BW2AAN000105ABAA

CGA Output 84000 BTU/HR

Cerified by: DUNKIRK

Boilers do turn on and shut down but usually they run for a little bit once fired over even when the call for heat is not that severe.

It is possible that the heat anticipator in the thermostat is not properly set for boiler/hot water usage and that could cause the thermostat to call for heat more often than the boiler system needs.

It could be a flame sensor problem if the unit has one.

It could be the Aquastat if the settings are not correct like having the differential to close causing the unit to cycle to often due to small variations in the water temperature.

Gas bills are high and going higher and the only true way to find out if the boiler is causing the gas bill to go up is with degree day calculations and usage of cubic feet of gas NOT the dollar amount of the bill.