Service manual

SECTION 10: OPERATION AND MAINTENENCE

Figure 12: Automatic Burner Control Sequence

Figure 13: Gas Valve for Models UH (A) (AS) 30 - 45

Burner sequence for Ignition Control

Flame Signal

Start Gas Valve

Ignition Spark

Thermostat 24 V

SHUT DOWN

RUN

START

ts = 10 seconds

Signals Output By Control

Required Incoming Signals

Flue Fan

Pressure

Switch

30 Sec. Purge*

*Purge time begins at pressure switch change over.

Axial Fan

30 Sec. Delay 90 Sec. Delay

30 Sec. Post Purge

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.

Gas

Outlet

Pressure

Regulator