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 and allows for higher water temperatures to flow through the system during a thermal disinfection process to protect against Legionella growth.

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 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 303 SS
2 Insert – CircuitSolver 303 SS
3 Spring 302 SS
4 Plug 303 SS
5 Thermal Actuator 303 SS
6 Carrier 303 SS
7 Union Nut 303 SS
8 O-Ring Buna-N
9 Check Valve (Optional) Glass Filled Noryl
10 Insert – Female Threaded 303 SS

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 be performed 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



  • 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

CircuitSolver®s are efficient and take the time typically required to manually balance systems at the end of the project out of the equation. We have started up systems in the afternoon to come in the next morning to find hot water perfectly balanced throughout all risers and zones.

— Christopher Meurer - J.C. Cannistraro, LLC
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