I have a circa 1970 forced hot water America Standard Boiler model 1BSE J1 with a Taco 007 pump located on a line coming from the bottom left (facing boiler) which is pumping hot water from the bottom of the boiler and up. The expansion tank is located on the return line and has no air scoop. My system is air bound. This is a single zone system supplying heat to a second floor. I would like to reverse the loop so that the return line feeds into the bottom of the boiler and out the top. I believe this was the original direction and was reversed. I supplied pics, help is greatly appreciated. [ATTACH]21537[/ATTACH][ATTACH]21538[/ATTACH][ATTACH]21539[/ATTACH][ATTACH]21540[/ATTACH]

OSV and residential Riello F40 I recently changed out my oil tank and removed the vinyl covered copper 3/8 line with a 3/8" orange line and a Garber screw on filter after the ball valve and Fire-O Matic . I said what the heck, and installed a 90 degree Sundstrand OSV with the red button on top, instead of the Webster style that requires an Allen wrench to over ride the OSV when required. I had about 10 gallons in the new tank and all ran fine. I filled the tank a few days later and the OSV on this gravity fed single pipe system shut down. The OEM said The Riello pump will not pull 3" of vacuum (the required suction to overcome the OSV. I thought all single stage pumps could pull 6" of vacuum.... They told me I must remove the OSV or convert to a two pipe system, or Tiger loop, or a day tank...Have others run into this problem??? I asked him why it ran with only 10 gallons to which he replied the small amount of oil wasn't enough to close the OSV until the oil level reached enough force to close it. Your thoughts???? Am I getting yanked around???