Thermostatic Mixing Valves and Diverting Valves


The thermostatic mixing valve/diverting valve is designed to maintain or proportion flow based on temperature in mixing or diverting applications.

In mixing applications where a controlled temperature outlet is required, the 3-way control valve (M/D) will modulate between the hot and cold inlet feeds (ports “B” and “C”) to mix your fluid to the desired specified temperature exiting the “A” port.

In diverting applications where the fluid must be directed from one section of a system to another, the thermal diverting valve (aka thermal bypass valve) will modulate inlet fluid temperature and divert return flow through a cooler/ heat exchanger or bypass it to a reservoir/ bypass loop when fluid temperatures are satisfied. This action assures rapid system warm-up, accurate control of fluid temperature, and reduced back pressure in the return.

Mixing and Diverting Thermal Valves

Mouse over an image of a thermostatic mixing valve/diverting valve to animate.

Thermal Diverting

Animation of Diverting Valve of Hot Temperature

Animation of Diverting Valve of Cold Temperature

Installed in diverting mode, the valve’s thermal actuator will sense the fluid temperature and automatically divert or switch the inlet flow to either of the two outlet ports depending on the valve’s specified temperature requirements.

Thermal Bypassing

Thermal Bypass 4 Port Valve Open

Thermal Bypass 4 Port Valve Closed

The TBV cartridge can be integrated into a 4-way manifold to monitor inlet flow and divert the fluid based on temperature. Cooler fluid goes through the valve bypass, while hotter fluid goes through the system’s cooler.

Thermal Mixing

Thermal Bypass Valve Mixing Hot/Cold Full Open

Thermal Bypass Valve Mixing Cold Open

Installed in mixing mode, the mixing valve’s thermal actuator will sense the temperature to automatically proportion the flow of hot and cold fluid from two inlet ports to produce the desired outlet port temperature.

Typical Applications

  • Battery Cooling
  • Cooling water control for radiator or heat exchanger
  • Direct cooling with raw water
  • Direct injection water heating
  • Electronics system cooling
  • Engine and compressor cooling system
  • Hydraulic fluid cooling systems
  • Hydraulic power units (HPUs)
  • Hydraulic thermal bypass
  • Loop-type circulation systems
  • Lube oil cooling control
  • Lube oil thermal bypass
  • Temperature control for baths, wash basins, and sinks
  • Temperature mixing or diverting
  • Thermal Management
  • Water saving applications

Design Features

  • Exclusive self-actuating Thermoloid® wax blend thermal actuator
  • Heavy-duty – rugged construction
  • Compact and low mass for fast response
  • Operates in narrow temperature band
  • Standard valve material is bronze or stainless steel


  • Self-operating – no external power source required
  • Minimal maintenance needed
  • Wide temperature range
  • Easy installation
  • Few moving parts – reduce system wear





1/2” M/D Valve - 316 SS Body, 300 Series SS Internals


1/2” M/D Valve - all 316 SS construction


1/2” M/D Valve - Bronze


1” M/D Valve - Bronze


1” M/D Valve - 303 SS


1” M/D Valve - 316 SS Special Order Only


2” M/D Valve - SS


  1. Seal material compatibility “X” available (replace singular X of part number with corresponding number below):
    1. 0 – Buna-N for air (to 250°F), water, fuel, oil, gas, and petroleum-based hydraulic oils
    2. 1 – Viton for air (to 450°F), fuel, oil, gas, and petroleum-based hydraulic oils
    3. 2 – EPDM for air (to 300°F), water, steam, ketones, and synthetic hydraulic oils
    4. 3 – Fluorosilicone for air (to 400°F), aerospace industry petroleum oils/fuels, and diester-based lubricants
  2. For most applications: pressure difference between hot and cold ports should not exceed 10 PSI
  3. Set-point temperatures “XXX” available: 035°F, 045°F, 050°F, 060°F, 070°F (+/- 8°F), 085°F, 090°F, 100°F, 105°F, 110°F, 125°F, 130°F (+/- 8°F), 135°F, 147°F (+/- 8°F), 152°F (+/- 8°F), 160°F, 170°F, 190°F, 200°F, 205°F, 210°F.
    1. Unless otherwise noted, during operation the valve will modulate the Cold side (C port) closed at 5°F below the set-point, and the Hot side (B port) closed at 5°F above the set-point.
  4. Customized temperature, materials, and port positions available upon request  – Contact our team


  • Sizes: ½”, 1”, 2”
  • Maximum Operating Pressure for ½”: 350 PSIG (24 BAR)
  • Maximum Operating Pressure for 1” & 2”: 250 PSIG (17.2 BAR)
  • Maximum Operating Temperature: 250°F (121°C)


Thermostatic Mixing/Diverting Valve Product Brochure
Thermostatic Mixing/Diverting Valve Installation and Maintenance Instructions