Is the location of the pump important in relation to the expansion tank and boiler?
Yes, the expansion tank is the point of no pressure change. If the pump is placed so that it pumps toward the expansion tank, the head produced by the pump will show up as a drop in pressure on the suction side of the pump. This drop in pressure is equal to the head produced by the pump. A pump that develops more than 12 feet of head should be piped so it pumps away from the expansion tank. This way, the head produced by the pump will show up as a rise in system pressure on the discharge of the pump. The positive pressure will improve the elimination of air problems in a system. The expansion tank and pump should be located after the boiler so the boiler is also at the point of no pressure change. The Pressure Reducing Valve (fill valve) should be connected next to the expansion tank.
