John Guest 25687 Thermostatic Mixing Valve 3/8 Inch HG135

Product Description

The JOHN GUEST 25687 is a compact thermostatic mixing valve (TMV) designed to blend hot and cold water supplies and deliver tempered water at a consistent outlet temperature. Built around the Heatguard 135 platform, it incorporates a rapid-response thermostatic element that continuously senses outlet temperature and adjusts to compensate for fluctuations in supply pressure or temperature. Stable operation is maintained at flow rates as low as 0.25 gpm, and the valve automatically reduces flow to a trickle if the cold water supply fails, protecting against scalding. Plumbing professionals install this valve at individual point-of-use locations, including standard faucets and electronic sensor faucets.

The 25687 is intended for individual point-of-use applications in residential and light commercial settings. It is particularly well-suited for installation at electronic sensor faucets where a compact, reliable TMV is required close to the fixture. The valve ships configured with a 3/8 inch compression fitting suitable for 3/8 inch OD tube and includes a cold water bypass tee, making it ready for direct in-line installation without additional fittings in most applications.

Key Features

• Rapid-response thermostatic element maintains constant outlet temperature under changing flow and supply conditions
• Automatic trickle-down safety response on cold water supply failure, reducing scalding risk
• Adjustable outlet temperature range of 100 to 120 degrees F for field calibration
• Operates at flow rates from 0.25 gpm up to 2.5 gpm at 45 psi
• Compression connection suitable for 3/8 inch OD tube with included cold water bypass tee
• Third-party listed for individual point-of-use applications; every unit tested on an automated station during assembly

Compatibility

Designed for point-of-use installation with individual faucets and electronic sensor faucets requiring a compact thermostatic mixing valve with 3/8 inch compression connections.

Installation Notes

Installation should be performed by a licensed plumber in accordance with applicable local plumbing codes and the International Plumbing Code (IPC). Shut off the hot and cold water supply and relieve system pressure before beginning work. Verify that supply temperatures and pressures fall within the rated ranges before commissioning the valve. Do not exceed the maximum operating pressure of 230 psi.

Technical Specifications

• Connection Size: 3/8 inches
• Connection Type: Compression, suitable for 3/8 inch OD tube
• Maximum Operating Pressure: 230 psi (16 bar)
• Adjustable Outlet Temperature Range: 100 to 120 degrees F (38 to 49 degrees C)
• Factory Set Temperature Range: 105 to 120 degrees F (40 to 43.3 degrees C)
• Hot Supply Temperature Range: 120 to 180 degrees F (49 to 82 degrees C)
• Cold Supply Temperature Range: 39 to 80 degrees F (4 to 27 degrees C)
• Minimum Flow Rate: 0.25 gpm (1.0 L/min)
• Maximum Flow Rate at 45 psi: 2.5 gpm (9.5 L/min)
• Included Accessories: Cold water bypass tee

Standard Information

• Brand: JOHN GUEST
• Manufacturer Part Number: 25687