The Watts CSM-81-F 2 1/2 is a 2-1/2" manual circuit balancing valve with Flanged connections. It features a semi-steel body and a ptfe seat.
This 2 1/2 inch flow measurement valve monitors system flow in medium to high flow rate HVAC units providing a highly accurate flow measurement. It consists of semi-steel body construction with a low-torque cylindrical plug design, flanged end connections, checked metering ports with drip caps, position indicator plate, positive shutoff, and two brass pressure taps. It is ideal in hot/chilled water units such as fan coil units, water source heat pumps, reheat coils, panel coils, branch lines, and pumps.
Features
- Accurate flow measurement
- Flanged end connections
- Positive shutoff
- Low torque
Common Questions
- Do I need a separate meter to read the flow?
- Yes. The CSM-81-F 2 1/2 is a differential-pressure device: it meters through dual PT (pressure/temperature) ports with checked drip caps. You connect a balancing meter (or a differential gauge) across the two ports, read the pressure drop, and convert it to GPM using the Watts flow chart for the 2-1/2" body. The valve does not display flow on its own. If you want set-and-read balancing without a meter, use the Watts iDROSET CSD direct-reading series instead.
- Can it also shut off the circuit?
- Yes. The CSM-81-F 2 1/2 gives positive, drip-tight shutoff, so it doubles as the service valve for the circuit and you do not have to buy and install a separate ball valve next to it. The memory stop preserves your balanced setting: close the valve for service, reopen it against the stop, and the circuit returns to the same flow without rebalancing.
- Can I use it on a domestic hot water recirculation line?
- No. The CSM-81-F 2 1/2 is not a lead-free model, so it is restricted to closed hydronic heating and chilled-water loops and other non-potable service. For DHW recirculation balancing, choose the lead-free equivalent — the Watts LFCSM-61-S (PT-port) or LFiDROSET CSD (direct-reading).
Specifications
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Type: Balancing
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Size: 2-1/2"
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Inlet Size: 2-1/2"
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Outlet Size: 2-1/2"
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Connection: Flanged
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Body Material: Semi-Steel
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Seat / Seal Material: PTFE
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Application: Hydronic Heating/Cooling
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Country of Origin: United States
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Warranty: 1 Year Limited
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MPN: CSM-81-F 2 1/2
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Lead-Free: No
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Balancing Type: Manual Circuit Balancing
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Valve Functions: Balancing;Flow Measurement;Shutoff
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Flow Readout: Dual PT ports, 1/4" SAE 45° flare, checked w/ drip caps
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Memory Stop: Yes
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Positive Shutoff: Yes
