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CSD-1 control system — Natural gas
Part Number 550-110-677/0299
9
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 CSD-1 control panel
terminal strip. The contact rating is 15 amps at 250VAC.
To reset the boiler, push the red reset button on the CSD-1 control panel.
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 flame-sense failure, the boiler may also experience lockout due to
shutdown of a manual reset control.
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, Check-out procedure — troubleshooting, of this Supplement and to
component manufacturer’s literature supplied in the boiler manual envelope for further
information on operating conditions.
Wiring — sequence of operationVI