Cleveland SteamCraft 10 Service Manual page 209

Models 24-CGA-10 and 24-CEA-10
TRIAL FOR IGNITION
Pilot Ignition
Following prepurge timing (S8660, S8670), or on the
call for heat (S8600, S8610), the module energizes
the first main valve operator. The first main valve
opens, which allows gas to flow to the pilot burner. At
the same time, the electronic spark generator in the
module produces an over 10,000 volt spark pulse
output. The voltage generates a spark at the igniter
(S8600A, B; S8610A, B) or igniter-sensor (S8600F, H,
M; S8610F, H; S8660; S8670) that lights the pilot.
If the pilot does not light, or the pilot flame
current is not at least 1.0µA and steady, the module
will not energize the second (main) valve and the main
burner will not light, S8600A, F; S8610A, F will
continue to spark as long as the thermostat calls for
heat or until the pilot lights.
Safety Lockout (S8600B, H; S8610B, H; S8660D,
S8670D)
These modules provide 100 percent shutoff
and safety lockout. A timer in these models starts
timing the moment the trial for ignition starts. Ignition
spark continues only until the timed trial for ignition
period ends. Then the module goes into safety
lockout. Lockout de-energizes the first main valve
operator and closes the first main (pilot) valve in the
gas control, stopping pilot gas flow. The control
system must be reset by setting the thermostat below
room temperature for one minute or by turning off
power to the module for one minute.
Cleveland Range, Inc.
SteamCraft 10 Service Manual, Chapter 8
Safety Shutoff with Continuous Retry (S8600M)
The S8600M provides 100 percent gas
shutoff, followed by retry for ignition. Operation on
ignition failure is the same as lockout modules, except
that a timer starts timing immediately following shutoff.
Six minutes nom. (five minutes min.) after shutoff, the
module restarts the ignition sequence. The ignition
trial, shutoff, wait sequence continues until either the
pilot lights or the thermostat is set below room
temperature to end the call for heat. The module can
also be reset by setting down the thermostat for one
minute.
MAIN BURNER OPERATION
When the pilot flame is established, a flame
rectification circuit is completed between the sensor
and burner ground. The flame sensing circuit in the
module detects the flame current, shuts off the spark
generator and energizes the second main valve
operator. The second main valve opens and gas flows
to the main burner, where it is ignited by the pilot
burner. On lockout models, the flame current also
holds the safety lockout timer in the reset (normal)
operating condition.
When the call for heat ends, both valve
operators are de-energized, and both valves in the
gas control close.
13
205
69-0463
Printed 3/93