Watts LFUSG-CS 3/8" Lead-Free Thermostatic Mixing Valve

The Watts LFUSG-CS is a 3/8" lead-free Under Sink Guardian point-of-use mixing valve. It blends hot and cold water to hold a field-adjustable outlet temperature of 80°F to 120°F. It is listed to ASSE 1070. It features a epdm seat. Rated to 150 psi. This model is certified lead-free for potable-water installations.

This Under Sink Guardian® mixing valve with Cross Sense™, is built to maintain a steady and safe water temperature at the fixture making it an ideal solution for facilities that prioritize user protection, such as hospitals, schools, businesses, and elder care homes. Designed for installation beneath sinks or counters, it helps prevent accidental scalding from overheated water. With its enhanced flow dynamics, the Under Sink Guardian ensures precise temperature regulation with minimal pressure loss. Internally, dual check valves prevent reverse flow between hot and cold supplies, while integrated strainers trap particles. Both housed within a removable, serviceable cartridge that promotes long-term maintenance and sustainability. The Cross Sense feature uses temperature-sensitive indicators to provide a clear visual of any cross-connection at the inlets.

Features

• Accurate temperature control with low pressure drop
• Quick change cartridge with integrated check valves and screens
• Cross Sense feature uses color changing visual indicators to detect cross-connection at hot and cold inlets
• ASSE 1070 listed and CSA certified
• Meets the reduced Q test statistic criteria of 0.5 ppb for lead per Section 9.5.1.1 of NSF/ANSI/CAN 61

Common Questions

Can I use this at a lavatory — is it ASSE 1070 listed?

Yes. This valve is listed to ASSE 1070, the standard for point-of-use scald protection, so it is legal to install it serving a lavatory, sink or similar fixture. Its outlet adjusts from 80°F to 120°F. Note ASSE 1070 does not cover showers — an in-shower device must be ASSE 1016 listed.

What temperature range does it deliver?

The outlet temperature is field-adjustable from 80°F to 120°F. Watts recommends a maximum setting of 110°F for handwashing. It holds that setting down to 0.25 gpm of flow.

Does it have integral checks?

Yes. Check valves are built into the hot and cold inlets to stop cross-flow between the supplies, along with integral filter washers/screens that keep debris off the thermostat. No separate check valves are needed at the valve.

Can I lock the temperature setting?

Yes. The adjustment is secured by a tamper-resistant locking cap, which is what makes this valve suitable for schools, healthcare and other public-fixture work where the setting must not be changed.

Specifications

• Type: Mixing/Tempering
• Size: 3/8"
• Seat / Seal Material: EPDM
• Max Pressure (psi): 150
• Backflow Protection: Backpressure
• Operation: Continuous
• Pack Quantity: 24
• Country of Origin: United States
• Warranty: 1 Year Limited
• MPN: LFUSG-CS
• Certifications: ASSE-1070, IAPMO
• Lead-Free: Yes
• ASSE Listing: ASSE 1070
• Install Point: Point of Use
• Outlet Temp — Min (°F): 80
• Outlet Temp — Max (°F): 120
• Minimum Controllable Flow (gpm): 0.25
• Integral Checks & Filter Washers: Yes
• Locking Temperature Adjustment: Yes
• Temperature Gauge Included: No
• Union Connections: No
• Applications: Lavatory / Sink