NO FLOW
Jandy
Insufficient Flow Through Heater or Flow Switch
Automation or heater reports NO FLOW when the Jandy pump is running; heater will not fire.
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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
Dirty filter restricting flow, Partially closed Jandy valve bypassing heater, Faulty heater pressure switch or flow sensor, Pump running at too low RPM (VS models)
How to Fix / Troubleshooting
Safety first: Turn off power to pump and heater before opening the filter or heater. Relieve filter pressure using the air relief valve.
- Check and clean filter:
- Backwash or clean cartridges to restore normal flow.
- Verify valve positions:
- Ensure Jandy valves are set to send water through the heater, not bypassing it.
- Increase pump speed (VS pumps):
- Temporarily raise RPM to the manufacturer-recommended speed for heater operation.
- Inspect heater flow/pressure switch:
- On Jandy heaters, locate the pressure switch or flow sensor.
- Check wiring connections and look for obvious damage.
- Replace the switch/sensor if it fails continuity tests per the heater manual.
- If NO FLOW remains: There may be internal heater restrictions or plumbing issues. Have a pool technician perform a full hydraulic and heater inspection.
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Repair Difficulty
Medium
3/5
Required Part
Heater Pressure Switch
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