1 Modulating valve lost calibration
2 Boiler water supply temperature or flow has dropped below requirement to satisfy demand
3 Control module not supplying 0 - 10 VDC control signal to valve
4 Modulating valve is not in AUTO Mode
5 No 24 VAC power supplied to modulating valve
6 Heat exchanger is improperly sized for load
7 Heat exchanger scaled on boiler side
8 High limit is tripped
1 - Remove cover on modulating valve electronics and press the recessed calibration button to re-calibrate the valve
2 - Ensure ball valves are open fully. - Ensure boiler water flow matches what is specified in the sizing table. - Ensure boiler side Y strainers are not clogged.
3 - Ensure the valve is wired correctly by referencing the wiring diagram on page 28 of this manual.
4 - Rotate valve handle until it is in AUTO Mode
5 - Ensure the valve is wired correctly by referencing the wiring diagram on page 28 of this manual. - Ensure the transformer is connected to the harness correctly and its built-in circuit breaker has not tripped
6 - Reduce load on heat exchanger or re-size heat exchanger.
7 - Clean and de-scale heat exchanger.
8 - Ensure high limit is set correctly so that power to the valve will be restored when the temperature returns to a low enough value.
