Heater emits a strong gas or combustion smell around the unit during operation.

Safety first: If you smell raw gas, immediately turn off the gas supply at the shutoff valve, turn off power to the heater, evacuate the area, and do not operate any electrical switches nearby. Contact your gas supplier or emergency services if the smell is strong.

Step-by-step checks (only if smell is faint and intermittent):

• Visual flame check: Through the sight glass, observe the flame. It should be mostly blue with minimal yellow tipping. Large yellow flames or soot indicate incomplete combustion.
• Inspect burner area: With gas off and the unit cool, remove the burner access panel and check for rust holes or cracks in the burner manifold and tray.
• Check gas connections: Using a leak detection solution (soap bubbles) and with gas turned on, carefully check threaded joints and unions for bubbles indicating leaks. Do not use open flame.

When to stop: Any confirmed gas leak or combustion abnormality must be corrected by a licensed gas technician. Do not attempt burner or gas valve repairs yourself.