121
Takagi
Flame Loss During Operation
Water heater stops during operation and shows error 121 on the Takagi remote.
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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
Fluctuating gas pressure, Dirty flame rod, Poor ground connection, Blocked vent causing unstable flame
How to Fix / Troubleshooting
Safety first: Turn OFF power and gas before opening the unit. Flame instability can indicate serious combustion or venting problems.
Steps:
- 1. Check other gas appliances: If stoves or furnaces also fluctuate or go out, contact your gas supplier to check supply and regulator.
- 2. Inspect vent and intake: Ensure the vent is not blocked, sagging, or disconnected. Clear any obstructions at the termination. Confirm intake and exhaust clearances.
- 3. Clean flame rod: Remove the flame rod and gently clean it with fine steel wool or emery cloth. Reinstall securely and ensure the wire connection is tight.
- 4. Verify ground: Confirm the unit’s ground wire is securely attached and that the outlet is properly grounded. Loose or missing ground can cause flame sensing issues.
- 5. Test operation: Restore power and gas, then run hot water. If error 121 recurs, a technician should check gas pressure, combustion, and possibly replace the flame rod or control board.
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Repair Difficulty
Hard
4/5
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