VI Wiring — sequence of operation
General
The following sequence of operation applies to all wiring diagrams in this Supplement — both water and steam.
Call for heat
On a call for heat (from thermostat or operating control):
1.Limit control and water level control contacts are assumed closed.
2.Vent damper (if provided) will open.
3.Ignition control checks for signal at pilot. (No signal should be present.) If no signal is sensed (normal condition):
a.Pilot solenoid opens.
b.Pilot ignition spark begins.
c.Pilot ignites.
d.Pilot proves.
If a signal is sensed (abnormal condition) by the ignition control, the control will lockout.
On failure to establish pilot flame signal within 15 seconds, the ignition control will turn off the pilot gas valve. It will wait 5 minutes, then retry for ignition. If the second ignition attempt fails, the ignition control will lockout and illuminate the red lockout light.
This will activate the alarm contact of the impulse relay, providing an isolated contact closure across terminals A1 and A2 of the
To reset the boiler, push the red reset button on the
4.Once pilot is proved the ignition control activates main gas valve. Main burners will ignite and boiler will continue to fire until terminated by limit action or no call for heat.
Lockout modes
In addition to lockout on
The boiler is equipped with a manual reset limit control and a manual reset low water cutoff. Should the limit control lockout, it can only be reset by pressing the reset button on the control. The manual reset probe low water cutoff can be reset after lockout by pressing the reset button on the control or by interrupting power momentarily.
Steam boilers — Do not substitute another manual reset low water cutoff for the one specified and supplied with the boiler. Other controls may not operate as intended and could cause serious operating problems or failures.
Troubleshooting
Refer to Section VIII,
Part Number | 9 |
