User manual

SECTION 11: OPERATION AND MAINTENANCE
27 of 47
Figure 15: Automatic Burner Control Sequence
Figure 16: Gas Valve for Models UHD[X][S] 75 – 125
Burner Sequence for Ignition Control
Flame Signal
Start Gas Valve
Ignition Spark
Thermostat 24 V
SHUT DOWN
RUNSTART
ts = 10 Seconds
Signals Output By Control
Required Incoming Signals
Flue Blower
Pressure
Switch
P
C
NO
NC
30 Seconds Purge*
*Purge time begins at pressure switch change over.
30 Seconds Post
If at any stage the flame fails, the control will retry
for ignition. The control has four trials for ignition
before a one hour lockout.
½PSI IN
C
ON
OFF
Regulator
Outlet
Pressure
Gas Inlet
Inlet Pressure
TOP VIEW
END VIEW
Description Part Number
Gas Valve 75 – 125 NG 90032505
Gas Valve 75 – 125 LP 90032506