Originally posted by dtlithonia1
.... I also set the pressuretrol to 2psi and the differential to one half pound. It says the differential is subtractive. That means the boiler should cut out at 2 lbs and back in at one half pound if I am still calling for heat. Is that right?
I would still lower the setting further. The 'big' houses (10+ radiators) I routinely service have no more than 1 psi set on the pressuretrol and they heat easily, with no surging. It do suspect, however,there is still oils and/or crud in the system that makes steam production difficult.