Watts 0559133 3/4 In Brass Lead Free Hot Water Extender Mixing Valve

All three ports on the Watts LF70A 0559133 are 3/4 inch socket connections: hot inlet, cold inlet, and mixed outlet. Socket means you sweat copper tube into the port rather than threading it, so plan on solder or an approved copper joining method at all three points. The outlet is also listed at 18 mm metric equivalent. There are no threaded ports on this valve, so if your piping is threaded you will need adapters.

Hot inlet should be between 120 and 160 degrees F and cold inlet between 40 and 85 degrees F. The valve also needs at least a 5 degree F difference between the hot inlet and your desired outlet temperature to regulate. If your tank runs below 120, the valve has nothing to mix down and you will not gain any usable capacity from it.

It needs a minimum of 30 PSI static pressure and is rated to 150 PSI maximum working pressure. Hot and cold supply pressures also have to be reasonably balanced: the valve tolerates up to a 25 percent pressure differential between the two inlets. On a well system or a low-pressure gravity feed below 30 PSI, it will not regulate reliably.

Rated capacity is 5.5 GPM at 10 PSI pressure drop, with a usable regulating range of 0.5 to 9 GPM. That covers a residential or small multi-family water heater outlet and two to three fixtures running at once. If your peak demand runs past 9 GPM, size up to a larger body or pipe two valves rather than pushing this one past its range.

The body is lead free brass, which is why the model carries the LF prefix. Finish is rough bronze, an unplated as-cast look, so it is intended for mechanical room and behind-the-wall piping rather than exposed decorative work.

No. The LF70A 0559133 has no cold water bypass, so every drop of delivered water passes through the mixing element. If your job spec calls for a bypass so the fixture still sees water if the element fails, this is not the model to order.

A hot water extender like the LF70A sits at the water heater outlet and lets you store hot (say 140) while delivering a lower tempered temperature to the building, which effectively increases the usable draw from the same tank. It regulates the whole-house supply between 120 and 160 degrees F. It is not a point-of-use scald-protection device, so where code requires a specific fixture-outlet limit at a tub, shower, or lavatory, that still needs a dedicated point-of-use thermostatic valve downstream.