OHt
Master Spas
Heater Tube Overheat / Localized High Temperature
Display shows OHt and heater shuts off, pumps may continue
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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
Scale buildup inside heater, Restricted flow through heater, Failing circulation pump, Misplaced temperature sensor in heater tube
How to Fix / Troubleshooting
Safety first: Turn off power and allow the spa to cool before working on the heater.
- Check and clean filters: Remove and clean or replace filters to ensure maximum flow.
- Inspect circulation pump: Confirm the circulation pump is running smoothly and not noisy or hot. Replace if weak.
- Descale heater (if needed): If you have hard water and see scale on heater unions, consider draining the spa and descaling the heater tube or replacing the heater assembly.
- Verify sensor placement: Ensure the temperature sensor in the heater tube is fully seated and not touching the metal wall directly in a way that could cause false high readings.
- Reset and test: After corrections, power cycle the spa and monitor for recurrence.
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Repair Difficulty
Hard
4/5
Required Part
Heater Assembly
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