Watts LFU5B-Z3 3/4 3/4 In Lead Free Water Pressure Reducing Valve, Npt Female Union X Npt Female, Adjust 25-75 psi

Both ends are 3/4 inch NPT female threaded, so it lands on standard 3/4 inch male NPT adapters or male-thread stub-outs. The inlet side is a union connection, which means you can break the valve out later without cutting pipe or spinning the whole assembly. On copper you will need a male adapter soldered or pressed on each side; the valve itself gives you no sweat ends.

Adjustment range is 25 to 75 psi (1.8 to 5.2 bar), and it ships set at 50 psi. Most municipal service into a house or a small commercial building is fine at that 50 psi factory setting, so a lot of installs go in without touching the adjusting screw. If you are feeding fixtures that want lower inlet pressure, or you are trying to knock down street pressure hard, 25 psi is as low as this one goes.

Lead free, with a body of lead free copper silicon alloy, which is the material Watts uses for potable water service. Trim and strainer are stainless steel and the seat disc is EPDM. It is also Buy American Act compliant, made in the USA, which matters on federally funded and many institutional jobs where domestic sourcing is a line item on the submittal.

The LFU5B-Z3 has a built-in thermal expansion bypass, so when the heater fires and pressure on the house side climbs above street pressure, the valve lets that expansion back out toward the main instead of trapping it. That is the failure mode that pops T and P relief valves on a closed system. It handles thermal expansion within the valve itself, but it does not replace an expansion tank where your local code specifically calls for one, and it will not bypass if the street side has its own check or backflow preventer upstream holding pressure.

Direction matters. The union is on the inlet, the supply side, and the outlet is a plain 3/4 inch NPT female. Pipe it with the union facing the incoming main so you can uncouple the valve for service without disturbing the downstream branch. Installing it backwards puts the regulator on the wrong side of the flow and it will not control pressure. Both ports are 3/4 inch NPT female threaded, so the connection sizes are identical and the union and the flow arrow are what tell you which is which.

A stainless steel strainer is built in, so you do not need to pipe a separate Y-strainer upstream to protect the seat. On well systems or on a main with sediment, that integral screen is what keeps grit off the disc and stops the pressure setting from drifting. It is stainless rather than a plated screen, so it holds up in continuous service and can be pulled and cleaned.

Maximum operating temperature is 160 degrees F, so it is fine on a hot water line running at typical domestic delivery temperatures but not on anything stored or circulated hotter than that. Minimum is 33 degrees F, meaning it needs to stay above freezing, so an unheated crawlspace or an exterior wall cavity is a bad location unless it is insulated and heat traced. Maximum working pressure is 300 psi (20.7 bar), well clear of any municipal supply.

No gauge on this one. If you want to read the reduced pressure without dragging out a hose bib test gauge every time, you either order a gauged version of the U5B family or tee a gauge into the line downstream. For a property manager standardizing across a building, the gauge is worth having on at least the main risers so a pressure complaint can be checked in seconds; on individual unit installs the ungauged valve is the usual pick.

The valve carries a corrosion resistant coating over a lead free copper silicon alloy body, with stainless steel trim and a stainless strainer inside. That combination is what handles aggressive water and damp mechanical rooms without the body scaling or the internals seizing. The EPDM disc is the wear part, and it is a rubber compound that holds up against domestic water chemistry rather than a leather or fiber seat that hardens over time.