A ARMSTRONG

refrigerating systems, hot water heating systems, and ventilating systems, comprising steam traps air vents, drainers for discharging liquid from gas flowing through a pipe, steam humidifiers, electronic humidifiers, "Y" strainers, steam piping manifolds, air purgers, pressure reducing valves, temperature regulator valves, basket strainers for separating solids from liquid flowing through a pipe, hot water heaters, steam coils, unit heaters, cooling coils, tank heaters, sold as a unit or as replacement parts for the foregoing systems