gas pressure

computerwhizyeah

Last fall I noticed (and heard) the effects of high gas pressure at the burners of an old CI sectional atmospheric boiler, with a input of 1,100,000 btuh. Owner was considering a new boiler with higher efficiency. I checked the input to the boiler (higher than rated by 300,000+) and upon checking manifold gas pressure noted that it was 9.4 in wc with only boiler running. Pressure in house is 13.5 in wc. Someone had removed regulator to boiler when installing new diaphram type gas valve. I suggested and installed new regulator to bring pressure to 3.5 in wc and told owner to wait on new boiler installation until spring fully expecting a lowering of gas usage and resulting cost. Surprisingly there was no change at all, past winter here was milder than 05-06 (using degree days from weather service)but usage was even a little bit higher. Temmperature ahead of diverter did drop from 430 to 350 degrees and usage was now 800,000 btuh. System and flu is clean, chimney ok, owner says heating habits were the same. I would like to know what is going on, old three and half story house, not insulated, oversized boiler, way too much ci radiation, controlled from thermostat - burner on-pump on, outdoor reset, 1/2 radiators have trvs, checked gas pressures many times, lowest reading ever was 8.7 prior to putting regulator in. Thanks in advance.