BWT
No Heat Demand Recognition
Heater does not start when pool pump is running and there is a call for heat
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Incorrect wiring of heater to pump or external thermostat, Flow switch not closing despite flow, Faulty water temperature sensor reading above setpoint, Control set to standby or cooling mode
How to Fix / Troubleshooting
Safety first: Turn off power before checking wiring.
- Check operating mode: Ensure the heater is set to HEAT mode and not COOL or OFF.
- Verify setpoint vs actual: Confirm the set temperature is higher than the current water temperature displayed.
- Inspect flow switch: Make sure the pump is running and valves are open. If the heater still does not detect flow, the flow switch may be stuck or faulty.
- Check external control: If controlled by an external thermostat or automation, verify that the control is actually calling for heat and that wiring is correct.
If the heater still does not start with confirmed flow and heat demand, a technician should test the flow switch and control inputs.
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Repair Difficulty
Medium
3/5
Required Part
BWT Flow Switch / Flow Sensor Assembly
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