Dettson furnace runs but produces no heat; blower runs continuously with room temperature air.

Safety first: If you smell gas, shut off gas at the main valve, turn off power, and leave the area. Call your gas supplier or emergency services.

• 1. Check thermostat settings: Ensure the thermostat is set to HEAT and the setpoint is above room temperature. Replace batteries if applicable.
• 2. Verify furnace power: Confirm the furnace switch is ON and the breaker is not tripped.
• 3. Confirm gas supply: Make sure the manual gas shutoff near the furnace is open and other gas appliances work.
• 4. Observe startup: With panels on, call for heat and listen: inducer should start, then ignitor glow, then gas valve click and flame. If the sequence stops before flame, suspect ignitor or gas valve issues.
• 5. Inspect ignitor (power off): Remove the burner door, locate the ignitor, and check for cracks or damage. Replace with the correct Dettson ignitor if defective.
• 6. If no improvement: Further diagnosis of the gas valve and control board should be done by a qualified technician.