How to Fix / Troubleshooting

Safety first: Turn off power and gas before opening the combustion chamber. Gas pressure checks must be done by a qualified technician.

Steps:

Check user settings: Ensure the hot water temperature on the Saunier Duval control panel is set high enough.
Verify flow rate: Very high flow can reduce temperature. Partially close the hot tap to see if temperature increases.
Clean burner: Remove and clean the burner ports to restore full flame coverage.
Descale heat exchanger: If the unit is older or in a hard water area, arrange for professional descaling of the primary heat exchanger.
Gas pressure: Have a technician measure and adjust gas pressure if necessary.

Warning: Do not attempt to adjust gas valve settings without proper tools and certification.

Water heater ignites but hot water is lukewarm or not hot enough

Possible Causes