99
Richmond
Flame Detection / Safety Shutdown
Error 99 appears and the Richmond tankless heater shuts down immediately after attempting to 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
Severe combustion problem, Blocked vent, Faulty flame sensor, Control board safety circuit trip
How to Fix / Troubleshooting
Safety first: Turn OFF power and gas. Do not attempt repeated restarts—this error indicates a serious safety condition.
- Check for vent blockage: Inspect intake and exhaust terminations and vent piping for any obstruction or damage. Clear blockages and repair venting as needed.
- Inspect burner and flame sensor: Clean the burner and flame sensor as described for errors 11 and 12.
- Do not bypass safety devices: Never jumper or bypass flame sensors or safety switches.
- Call a professional: If error 99 persists after basic cleaning and vent checks, a qualified technician must inspect the unit, verify combustion, and test the control board and gas valve.
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Repair Difficulty
Professional Required
5/5
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