Watts 0009118 3/4 In Lead Free Water Pressure Reducing Valve, Npt Female Union X Npt Female, Adjust 25-75 psi

Both ends of the Watts LFU5B-Z3 are 3/4 inch female NPT, so it mates to 3/4 inch male NPT nipples or male adapters on either side. The inlet is a union female NPT connection, which means you can break the valve out later without cutting pipe or disturbing the downstream run. On a copper line you need a male adapter sweated or pressed onto the tube at each side.

The 0009118 has a thermal expansion bypass built in, so pressure that builds behind the valve from a water heater cycling can relieve back toward the street rather than climbing against a closed seat. That bypass handles thermal expansion within the system; it is not a substitute for a properly sized expansion tank where the local jurisdiction or the heater manufacturer calls for one on a closed system, but it is the feature that separates this model from a plain non-bypass reducing valve.

The body is a lead free copper silicon alloy, with stainless steel trim and an EPDM disc, which is the construction used for potable water service in both commercial and residential systems. Nothing in the wetted path is a leaded brass casting.

A stainless steel strainer is integral to the valve, so you do not have to pipe a separate Y-strainer upstream. That matters on a municipal main with sediment or on a building coming back online after a main break, since grit on the seat is the usual reason a reducing valve starts creeping. Leave clearance at the inlet union so the strainer can be pulled and rinsed.

No gauge is supplied with the 0009118. To read and set the reduced pressure you will need to tap a gauge into the downstream piping or use a hose bibb gauge on the nearest outlet. Order the gauge separately if you want a permanent readout at the valve.

The valve is rated to 160 degrees F (71 C), so it will handle domestic hot water at normal storage temperatures. The lower limit is 33 degrees F (0.5 C), which means it cannot be installed anywhere it may freeze, so an unheated crawl space or an exterior wall cavity needs insulation and heat trace. Standard practice is to set it on the cold supply ahead of the water heater so the whole building, hot and cold, sits at the reduced pressure.

Order Watts part 9118, the LFU5B-Z3 in 3/4 inch with union female NPT inlet and female NPT outlet. It is a single configuration, so there is no finish, handing, or connection option to get wrong when you reorder, and every unit arrives preset at 50 psi. Standardizing on it means one spare on the shelf covers any of the 3/4 inch services, and any tech who has changed one has changed them all.

The union inlet is the practical difference. When the strainer clogs or the seat wears, you back off one union nut and the valve comes out; a sweat-in-line valve means cutting pipe and re-soldering with water in the line. On a building where the same valve gets serviced every few years, that turns a two-hour job into a twenty-minute one. Both ends are 3/4 inch female NPT, so you adapt the existing copper once and never touch it again.