Combustion checking procedure

What happens, in order

1. Operation 1 Connect a manometer to the line pressure test port (Torx 10 screw 1). Enable Test Mode by holding RESET for 10 seconds and check gas inlet pressure against the table for the gas type under all operating conditions.
2. Operation 2 Remove the combustion test port plug and insert a calibrated combustion analyzer.
3. Operation 3 Create a heat demand at the highest setting or maximum DHW draw. Activate the TEST function by holding RESET for 10 seconds, then press the button for maximum power. Wait 1 minute and read CO2 and CO. Adjust the max gas valve setting screw 4 (clockwise raises CO2, about 0.3% per turn) if needed.
4. Operation 4 With the TEST function active, select minimum power and wait 1 minute. If min CO2 is higher than max CO2, or lower by more than 0.3%, adjust screw 2 (counter-clockwise lowers CO2, clockwise raises it). If min CO2 changes, repeat the max adjustment.
5. Operation 5 Exit Test Mode by pressing RESET. Turn down the thermostat or stop DHW draw. Reset thermostatic valves in heating-only systems. Check for gas leaks, reinstall the front cover, and reinstall the combustion test port.

Timings and thresholds

Models

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