CircuitSolver Union Thermal Disinfection (CSUTD-D)

CSUTD D Blue Background 500x200 RGB - CSUTDThe CircuitSolver® Union Thermal Disinfection Dual Balancing valve (CSUTD-D) thermostatically balances a domestic hot water recirculation system while allowing higher water temperatures to flow through the system during thermal disinfection.

Factory set to your specified temperature requirements, the CSUTD-D is the ideal balancing solution for dynamic systems employing thermal disinfection to protect against Legionella and other bacterial growth.

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How It Works:

The CircuitSolver® line of thermostatic balancing valves automatically and continuously adjust flow through a domestic hot water recirculation system to maintain the specified temperature at the end of the branch/riser.

The CSUTD-D thermal balancing valve uses two thermal actuators to control water flow through a branch/riser. The first low-temperature actuator balances the domestic hot water system (DHWS) during normal conditions. When the water temperature in the branch reaches the set-point of the low-temperature actuator, the valve modulates to its closed* position to keep the hot water at the fixtures and force the water from the water heater onto the other branches maintaining a constantly balanced system.

CSUSF Temp Curve - CSUTDThe low-temperature actuator will reopen during the thermal disinfection process, allowing the high-temperature water to flow through the branch again. When the water temperature reaches the set-point of the second high-temperature actuator, the CircuitSolver® will modulate to its closed* position again to keep the high-temperature water at the fixtures for disinfection.

The CircuitSolver® Thermal Disinfection valve is tamper-proof and operates at the ideal line temperature for standard balancing while allowing higher temperatures during disinfection processes. It is the perfect solution for a maintenance-free high-temperature flush.

*Note: The valve will never fully close, allowing a small flow bypass to the return to avoid dead-heading the recirculation pump.

Valve Components:

The CSUTD-D valve is comprised of 100% stainless-steel components, a high-quality O-ring, and an optional check valve.

For typical specifications and installation/maintenance instructions, visit the Typical Specs + IMI Steps page.



1 Valve Body w/ Union Threads 300 series stainless steel
2 Insert – CircuitSolver 300 series stainless steel
3 Spring 300 series stainless steel
4 Plug 300 series stainless steel
5 Thermal Actuator 300 series stainless steel
6 Carrier 300 series stainless steel
7 Union Nut 300 series stainless steel
8 O-Ring Buna-N
9 Check Valve (Optional) Glass Filled Noryl
10 Insert – Female Threaded 300 series stainless steel

Typical Applications:

The CircuitSolver Thermal Disinfection valve can be used in any building with a domestic hot water recirculation system to keep fixtures supplied with hot water while also allowing high-temperature flushing procedures to protect against Legionella and other bacteria growth.

Used in commercial buildings of all sizes and DHWS’ with varying complexity, installations often include hospitals, schools, hotels, high-rise buildings, and multi-family apartment buildings.

To see CircuitSolver® installations in your area, visit our installations page.

CircuitSolver® thermostatic balancing valves can also balance the return flow between the master mixing valve and the water heater. To learn more about this application, go to the Balancing a DHWS Return with CircuitSolver page.



  • Automatically and continuously adjusts to balance domestic hot water systems
  • Eliminates balancing labor and callbacks
  • Direct replacement for manual balancing valves
  • Reliable, long-lasting thermal actuators
  • Allows for thermal disinfection of the DHWS to protect against bacterial growth
  • Long service life and 3-year warranty


  • NSF/ANSI/CAN 61 & 372 Certified
  • Lead Free
  • Fully compliant with Section 1417(d) of SDWA, the Safe Drinking Water Act
  • Supports efforts toward LEED Certification
  • Complies with the Buy American Act


  • Sizes: 1/2″, 3/4″ & 1″
  • Fixed Standard Balancing Temperatures:
    • 100°F (37.7°C)
    • 105°F (40.5°C)
    • 110°F (43.3°C)
    • 115°F (46.1°C)
    • 120°F (48.8°C)
    • 125°F (51.6°C)
    • 130°F (54.4°C)
    • 135°F (57.2°C)
    • 140°F (60.0°C)
  • Fixed High Temperature for Thermal Disinfection is 170°F (76.7°C). Consult the factory if another temperature is required.
  • Max Working Pressure: 200 PSIG/14 BAR
  • Max Working Temperature: 250°F/121°C
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