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Brass thermostatic mixing valve, compact rectangular body with solder inlets and outlets, polished metal finish

Watts

Watts 1/2 LF MMV-US Mixing Valve Brass .5-23 gpm 150 psi

SKU CH-D1QC-C797M MPN 1/2

Thermostatic mixing valve in brass delivers 0.5 to 23 gpm at 150 psi with an 80 to 120°F outlet range and integral check valves

  • TypeDrain Components
  • Delivers precise temperature control with a solid-wax thermostat
  • Supplies .5 to 23 gpm for flexible flow requirements
  • Withstands 150 psi maximum pressure for durable service
  • Handles hot inlet up to 180 °F and cold inlet down to 39 °F
  • Includes integral filter washers and check valves for cleaner operation

Thermostatic Mixing Valve

This Watts 1/2 LF MMV-US valve blends hot and cold water to a set temperature for residential or light-commercial plumbing systems. It accepts solder connections on both 1/2 in inlets and outlets and operates with a solid wax hydraulic thermostat. The brass body includes integral filter washers and check valves for debris protection and backflow prevention. Suitable for installers needing a lead-free mixing device rated to 150 psi.

Flow Range and Temperature Limits

The valve handles 0.5 to 23 gpm and delivers mixed water between 80 and 120 Degrees F. Cold supply must stay within 39 to 85 Degrees F while hot supply must stay within 120 to 180 Degrees F. Exceeding these inlet ranges or the 150 psi pressure limit will cause the thermostat to lose control or damage internal components. Select this model only when your system flow and supply temperatures fall inside the stated windows.

Solder Installation Notes

Both ports are 1/2 in solder, so the valve must be sweated into copper pipework using lead-free solder and flux. Remove the internal cartridge before heating to protect the wax thermostat and filter washers from heat damage. After cooling, reinstall the cartridge, pressure-test to 150 psi, then adjust the outlet temperature with the calibrated knob. A common error is leaving the cartridge in place during soldering, which ruins the thermostat and voids the part.

Highlights

  • Delivers precise temperature control with a solid-wax thermostat
  • Supplies .5 to 23 gpm for flexible flow requirements
  • Withstands 150 psi maximum pressure for durable service
  • Handles hot inlet up to 180 °F and cold inlet down to 39 °F
  • Includes integral filter washers and check valves for cleaner operation

Specifications

TypeDrain Components
BrandWatts
Model1/2 LF MMV-US

Questions about this item

How does the 0.5 to 23 gpm flow range translate to everyday hot-water delivery?

The valve blends hot and cold water to maintain a steady outlet temperature across that flow span, so showers and sinks receive consistent warmth even when demand changes.

What does the 150 psi maximum pressure rating limit in a residential system?

It sets the highest supply pressure the valve can handle; typical home pressure is well below this, so the valve operates safely without additional pressure-reduction measures.

What piping preparation is required for the 1/2-inch solder inlets and outlets?

Clean the copper tube ends, apply flux, slide the valve into position, then solder each joint; the 5 3/8-inch height and 4 7/8-inch width determine the clearance needed in the wall cavity.

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