Supported water flow meter CST FSI-T10 indicating double water flow

I’ve connected a CST FSI-T10 and compared the water flow between the Rachio-3 and the water company’s meter. With the Rachio configured for the CST FSI-T10 and doing a callibration, the flow reported by the Rachio is roughly double that of the water company.

Flow sensor is connected between C and S2.

Have I missed something in the setup?

You have it wired wrong:
Wired flow sensor compatibility and installation (

Meters connect to 24VAC-

Yes, connecting sensor to 24v made the difference. Previous sensor (not supported) didn’t work on 24v connection. Have both rain and flow sensors connected to 24v and s1 and s2.

Accuracy of the flow sensor is closer now to real usage.