Smith GVX-Series User's Information Manual page 3

C. Sequence of Operation.
1. Thermostat calls for heat.
2. Limit control energizes circulator.
3. Limit control energizes B1 circuit if boiler water
temperature is below setpoint minus differential.
Setpoint is calculated according to thermostat
cycle and economy/efficiency setting. See limit
control literature for further information.
4. BR relay energizes blower.
5. Negative pressure induced by blower switches
Pressure Switch, continuing power through
closed contacts (BR-2) and flame roll-out
switch.
6. Gas valve energizes.
a. Ignitor on.
b. Pilot gas on, igniting pilot.
USER'S INFORMATION MANUAL
7. Pilot flame detected.
a. Ignitor off.
b. Main gas on, igniting main burners.
Note: If pilot flame is not detected within 90
seconds, the igniter and pilot are turned
off for 5 minutes. The sequence then
resumes at Step 6a.
8. Call for heat ends.
a. Pilot and main gas off, extinguishing pilot
and main burners.
b. Blower and circulator off.
If this sequence is not followed exactly, follow
instructions TO TURN OFF GAS TO APPLIANCE
(see Figure 2), and contact a qualified service
agency.
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