Reference
Typical Gas Train Layout with Direct Spark Ignition
This is a typical gas train. The gas train in your unit may be different.
Burner Differential
Pressure Sensor
(Airflow Switch)
to Burner
Modulating
Combination Shut-Off
Low Gas Pressure
Valve
Valve/Regulator
Switch (optional)
Burner Manual
Shut-Off Valve
Low Gas Pressure
Test Port
High Gas Pressure
Test Port
Gas Connection
34
Model VSU Make-Up Air
®