Measure manifold pressure from the burner box

What is going on

Manifold pressure on this Trane has to be referenced to the burner box, not read against room air at the valve outlet. Gas work, so a licensed technician should set it. Get the reference right or the reading means nothing, and a bad reading leads to overfiring or sooting.

Likely causes

• Manifold pressure read without the burner box reference
• Tap plug not sealed after adjusting, leaving a gas leak
• Tee or tubing connection leaking at the reference line

Check in this order

1. Install a field-supplied tee in the tubing between the burner box tube and the gas valve.
2. Keep the regular gas valve outlet pressure tap in use as well.
3. Check manifold pressure at the burner box reference.
4. After adjusting, replace the manifold pressure tap threaded plug.
5. Leak check the plug and tubing connections with leak detector solution.

More furnace guides

• Abnormal conditions and protection
• Adjust gas valve manifold pressure
• Air for combustion and ventilation in non-direct vent installs
• Airflow adjustment check
• Airflow and temperature rise check
• Bottom return filter rack installation (upflow)