We advise no; keep the body above the horizon when mounted in a horizontal pipe, or mount it in a vertical pipe. If mounted under the pipe there is a potential for dirt and other sediment to settle in the diaphragm and other moving parts of the cartridge which may, over time, affect the performance of the valve. The 535H Series Pressure Reducing Valve is high-performance, durable product that will provide many years of reliable service when installed according to the instructions. Water conditions vary widely; if scale or sediment build up enough to affect the performance of the PRV, the entire cartridge can be easily removed for cleaning or replacement without removing the valve body from the piping.
July 26, 2017