its a chaffoteaux!!! what do you expect.....i suggest you replace the thing with a decent reliable boiler!
Hope this helps
Steve C Dukinfield
March 2011
Try taking account of the colder incoming water is the easy answer.
Otherwise, generally speaking, it will be a worn diaphragm not allowing full gas burner pressure
Carefree
December 2010
I can answer this question...
I have a Chaffoteaux & Maury water heater Britony 11 T???