an hydraulic column choke valve and reamer adapted to hot water heating boilers and the like , permitting maintenance on low water fuel cut - off controls and similar columns without draining , characterized by a universal valve body which interchangeably mounts a reaming assembly and / or choke assembly , the latter of which may be retained in the column after removal of the valve body . the water column choke is adapted to columns of variant horizontal cross section without exchange of the valve body , per se .