What is a Circuit Setter?

A circuit setter is a calibrated balancing valve mainly used in the field to set, measure, and verify flow in hydronic systems. In practical terms, a circuit setter valve is a helpful piece of equipment to help technicians adjust water flow to match the required GPM for a coil, terminal unit, heat exchanger, or piping branch.

This valve works by creating a measurable pressure drop across the valve (between inlet and outlet). By reading that differential pressure acting in the valve in conjunction with the manufacturer's performance data, the technician can estimate the flow rate and adjust the valve position as needed.

Using the manufacturer's performance curves, a system balancing method involves pre-setting the valves to achieve optimum system flow balance (at minimum horsepower). The flow can be determined by knowing the pressure drop through the device and its Cv (the flow rate in GPM through the device that results in a 1 psi pressure drop).

What Does a Circuit Setter Do?

A circuit setter helps balance water flow across a water system. Without balancing, water tends to follow the path of least resistance, which can leave some circuits with too much flow and others with too little, in other words, no flow control.

A circuit setter balancing valve gives the technician three useful functions in one device: a way to adjust flow, a way to measure pressure drop, and a way to return the valve to a known position after service. This makes it useful for system startup, commissioning, troubleshooting, and future maintenance.

Circuit Setters vs. Manual Balancing Valves

Circuit setters feature a built-in balancing valve system as well as monitoring and measuring points that automatically calibrate a water system. In addition, because there's no need to readjust the valve by hand, circuit setters allow for easy expansion of the water system into other parts of the building project.

One of the main benefits of a circuit setter is its shutoff valve capability, which allows the water to be shut off in an area of the system to save water and energy when part of the building is not in use. Shutting off the water to a particular building area is an excellent feature for large construction projects that may undergo renovations or need additions. However, circuit setters may have more features than are necessary for smaller buildings and homes.

Manual balancing valves may need to be installed at more junctions of a piping system and require hand calibration, but they offer a time-tested and much less costly method of keeping a water system balanced.

Manual balancing valve benefits include the ability to read low flow rates very accurately while saving energy. In addition, in a smaller water heating or cooling system, hand adjustment of manual balancing valves does not pose a problem, and costs are generally much lower.

For a deeper comparison between standard balancing valves and circuit setter balance valves, read our guide: Circuit Setters vs. Balancing Valves.

Should Circuit Setters Be Placed on the Supply or Return Side?

Traditionally, circuit setters are placed on the return side of the system. For example, if the balance valve is placed on the return after a control valve and has a set of ports to check differential pressure, you can use it to find a wealth of information. Such as the pressure drop of the piping in that zone, the return pressure, actual flow in the zone, what the flow is with other zones on, supply pressure at that point, etc.

This location helps reduce air and noise problems within the system. Compared with placement on the supply side, flow balance valves on the return side will reduce the amount of free air in the coil and, thus, the potential for noise.

Circuit Setter Balance Valves are unidirectional and must be installed with the arrow cast on the valve's body pointing in the flow direction. Bell & Gossett Circuit Setter Balance Valves may be installed in vertical or horizontal pipes with the valve stem pointing up or down.

Bell & Gossett Circuit Setters

Bell & Gossett Circuit Setters have been the standard for proportionally balancing hydronic HVAC systems since 1968. The system balance method developed by Bell & Gossett assures optimum system flow balance at minimum pump operating horsepower. Circuit Setter valves can be pre-set using the B&G Circuit Setter Balance Valve Calculator, curve booklet G10091, or the System Syzer application.

Circuit Setters are available in various sizes and styles to meet any system demands. Brass valves, in sizes 1/2" through 3", utilize a full-port ball valve with a calibrated nameplate and feature a memory stop and two integrated pressure/temperature ports for easy ∆P measurement. Additionally, All Brass Circuit Setters are CSA certified to comply with the low lead requirements of California, Vermont, Maryland, Louisiana, and NSF//ANSI 372.

For larger-sized systems, Circuit Setters are available in a ball style (2-1/2" to 4") and a globe style (4" to 12"). The globe-style valve includes a multi-turn stem, calibrated nameplate, memory button for easy re-setting of the valve position after shut-off/isolation, and integrated pressure/temperature ports.

Bell & Gossett is one of the most recognized names associated with circuit setter balance valves, and many technicians use the terms “Bell & Gossett circuit setter” or “B&G circuit setter” when referring to this style of calibrated balancing valve. For a more detailed look at how these valves are applied in hydronic balancing, read: How Bell & Gossett Circuit Setters Are Used to Balance Hydronic Systems.

Bell & Gossett Circuit Setter Features

• Lead-free brass models 1/2" through 3" are suitable for use in all potable water systems

• Calibrated, accurate flow control and measurement

• Sizes from 1/2" to 12":

• Ball valve style 1/2" through 4"
• Globe valve style 4" to 12"

• Multiple end connections available:

• Union – upstream (1/2" – 2")
• Sweat (Female) and NPT (Male and Female) (1/2" – 2")
• Flanged 2-1/2" to 12"
• Grooved 4" to 12"
• Flow range up to 7,200 GPM
• Pre-balance design capability
• Integrated valved readout ports

How to Set a B&G Circuit Setter

To establish the required system flow:

1. Open the Circuit Setter to the 100% open position. The position of the indicator ring can be read to determine the Circuit Setter position (the amount the Circuit Setter is open or closed) through the nameplate slot.
2. Energize the zone, Circuit Setter, and/or system pump(s) so fluid flows through the Circuit Setter.
3. Using Bell & Gossett model RP-250B readout probes, attach a Bell & Gossett differential pressure readout kit to the readout valves on the Circuit Setter balance valve.
4. Read the differential pressure across the Circuit Setter.
5. Refer to the 100% open pressure drop curve chart in the Curve Booklet for the size of Circuit Setter installed and read the flow corresponding to the measured pressure drop. The Cv shown on the curve may also be used to calculate or read the flow from Scale 5 in the Bell & Gossett System Syzer application.
6. If the GPM disagrees with the specified GPM, close the Circuit Setter accordingly. Repeat steps 5 and 6 until the required results have been achieved.

To use the memory stop feature:

1. After the Circuit Setter's final adjustment, loosen the memory stop locking screw.
2. Position the memory stop so it is as far up on the Circuit Setter stem as it will go.
3. Tighten the memory stop locking screw.
4. The Circuit Setter can now be closed for system service and returned to its present position after service has been completed.

To use a Bell & Gossett Circuit Setter to proportionally balance a system:

1. Open all Circuit Setters fully on a single-pump system.
2. If more than one branch circuit is used, start the balance procedure by reading all of the flows to the units in a branch. Each unit (coil) should have its own Circuit Setter for flow balancing. Using Bell & Gossett PR-250B readout probes, sequentially attach a Bell & Gossett differential pressure Readout Kit to the Readout Valves on each Circuit Setter. Refer to the Curve Booklet to obtain flow based on pressure drop.

Circuit setters, manual balancing valves, automatic balancing valves, and pressure balancing valves are related, but they do not all perform the same function. A circuit setter is mainly used to set and verify flow through a circuit, while other balancing valve types may respond differently to pressure changes or system conditions. For more context on pressure balancing terminology, see: What Is a Pressure Balancing Valve?

Circuit Setters Available at Liberty Supply

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Liberty Supply is a customer-centric organization. We focus on hydronic and steam systems for commercial and industrial facilities. As a B2B distributor within the "needs business," our foundational pillars are knowledge, communication, and speed. Relationships are built through hard work and consistent delivery of value. No exceptions. Our team maintains that with each transaction, we start back at zero.

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