CircuitSolver Union Assembly (CSUAS)

CSUAS Banner - CSUASThe CircuitSolver® thermostatic balancing valve automatically balances a domestic hot water system (DHWS) in a fraction of the time required by traditional manual balancing methods.

The CircuitSolver® Union Assembly with Strainer features a union with an optional check valve built into the body of the CircuitSolver®, particulate strainer, and isolation ball valves on either side to reduce the number of system components to be installed and minimize potential leak points. The valve features an integrated O-ring and is factory assembled for a leak-free seal.

How It Works:

The CircuitSolver® Union Assembly with Strainer (CSUAS) balancing valve is installed at the end of each branch in a DHWS, downstream of the last fixture, to monitor the water temperature using our exclusive Thermoloid® blend wax actuator technology. The valve will automatically modulate open or close in response to changing temperatures to maintain a specified temperature at the end of each branch. This continuous response to temperature variation enables each hot water branch to quickly and consistently direct hot water flow to where it is needed – No manual balancing required.

The CSUAS will never fully close, always allowing a small bypass of flow to the return to avoid dead-heading the recirculation pump. The limited flow to your return line will reduce system wear, electricity, and water usage, and improve overall system operation.

Valve Components:

The CircuitSolver Union Assembly valve with Strainer is comprised of 100% stainless-steel components, a high-quality O-ring, two isolation ball valves, an integrated strainer, and an optional check valve.

CAUAS Callouts 1024x268 - CSUAS
1 Valve Body w/ Union Threads 303 stainless steel
2 Union Nut 303 stainless steel
3 Female Threaded Inset 303 stainless steel
4 Plug 303 stainless steel
5 Operating Spring 302 stainless steel
6 Thermal Actuator 303 stainless steel
7 O-Ring Buna-N
8 Check Valve (Optional) Glass Filled Noryl
9 Ball Valve, ½” MxF
10 Strainer Stainless steel

Typical Applications:

The CircuitSolver® Union Assembly with Strainer is often specified for new domestic hot water systems that may have particulates inside of the system as a result of construction or in water systems that have a history of particulate/dirt issues.

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

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


  • All Stainless Steel – Corrosion Resistant Construction
  • High thrust actuator keeps orifice free of debris
  • Union with integrated O-ring for a leak-free seal
  • Optional check valve built into the body
  • 2 M/F ball valves assembled and leak tested
  • Integrated 20 mesh strainer
  • Never fully closes, some water always passing through
  • Long service life and 3-year warranty



  • Sizes: 1/2”, 3/4″ & 1”
  • Fixed 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)
  • Max working Pressure: 200 PSIG/14 BAR
  • Max Working Temperature: 250°F/121°C

With CircuitSolver®, 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. We make sure to get the check valves included, so there is never an issue with direction of flow. We are also getting the complete setups with isolation valves to take any extra steps of fabrication out of the picture.

— Christopher Meurer - J.C. Cannistraro, LLC