1" Lead-Free Cast Copper Silicon Alloy Water Pressure Reducing Valve - Watts LFN45B Series with Double Union NPT Threaded Female Connection & Elumator Disc | Adjustable 25-75 PSI, Max 400 PSI | Ideal for Residential Plumbing, Irrigation Systems & Industrial Water Pressure Control

I purchased the 1” Watts LFN45BM1-U to replace my 30 year old Watts N35B. It is the exact same length. This came with two O rings, and a flange. The flange has 1” female threads. A second flange can be purchased depending on the configuration needed. The unit also has 1” female threads on both the inlet and outlet. My original installation used a flange on the inlet and threads on the outlet. The price was right and Amazon delivered it the next morning!Installation tips: If your replacing an older PRV where you have a flange on one end and threaded on the other end, you may have difficulty getting enough clearance to unthread, remove and replace the PRV. Mine was installed on a very short section of 1” copper pipe. It came up through my garage floor through a shutoff and the PRV and then went to an elbow. To get enough room I used a board and a handcut wedge and hammer to carefully prop up the pipe at the elbow to gain enough room. I screwed one end on and then carefully insert one of the O rings before tightening up the flange. For some reason Teflon tape failed to seal twice, I ended up using pipe dope.The symptom that lead to the replacement was a sudden spike in pressure when turning on a tap after having heated hot water. I reasoned that I needed an expansion tank, as per code for a closed system. My house built in 1994 never had one. After installing the expansion tank properly I was getting an extended amount of high pressure. When I installed the expansion tank I measured the water pressure to be 60 psi. Purchased a new maximum reading pressure gauge for my hose bib and discovered the pressure would slowly creep up to 82 psi or 94 psi if the expansion tank valve was closed. Isolating the hot water heater also showed sharp increases in pressure. With a faucet running the old PRV would maintain around 50 psi but would slowly build by its own (pressure creep). The new valve is supposed to be set at the factory for 50 psi, but seems to actually be providing 55 psi. Worked great, didn’t bother to change it.If this new PRV fails early I will update my review