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Venting Hoffman Differential Loop and other issues
I have an old Peerless Boiler that has a Hoffman Differential Loop. It is a hot water closed system and the most remote radiators lately have been only partially heating. My plumber told me to fill the boiler and turn up the heat to create steam and use up the air that must be in the boilers. There is a vent on the Differential Loop that is a Dole that I need to replace. Any suggestions on whether the Dole is the best vent or if there are other approaches to ridding the air? The house is 85 years old and the radiators are Hoffman which I have been unable to find any valve replacements for. Any wisdom is appreciated