50
CL3
Series
Sequence of Operation
Standby:
The 35-66 control continually checks for internal faults, circuit integrity, and relay contact
positioning.
Starting Circuit:
Upon a call for heat, the control verifies that the differential switch is in the proper
position (open). The control energizes the fan. Once operational static pressure is achieved, the
differential switch will close initiating the ignition sequence. The glo-bar is powered and the gas
valve opens after 45 seconds. If the flame is not sensed, the heater will attempt to re-ignite for a
total of three (3) trials for ignition before proceeding to soft lockout.
Single Stage Running Circuit:
After ignition, the flame rod monitors burner flame. If sense of flame is
lost, the control closes the gas valve within one second and a new trial sequence (identical to the
starting sequence) is initiated. If flame sense is not established within 8.5 seconds, the heater will
attempt two (2) additional ignition sequences before proceeding to soft lockout. The control can
be reset by briefly interrupting the power source.
Two Stage Running Circuit:
The second stage on the gas valve is powered directly from the second
stage of the thermostat. In order for two stage to flow to a higher output, single stage must be
energized as well. The thermostat determines which stage to maintain for the desired
temperature.
Shut Down:
When the thermostat is satisfied, the fan will enter a two (2) minute post-purge cycle. Refer
to Soft and Hard Lockout under Diagnostics below.
Diagnostics
Lockout:
The controls will automatically lockout the heater system when an external or system fault
occurs. There are two types of lockout:
Soft Lockout:
The heater will attempt to light three times. In the event of a failed attempt to light, (gas
pressure, valve, no flame sense etc.), the heater will enter a soft lockout period for 15
minutes and then attempt to light three more times before entering Hard Lockout
mode.
Hard Lockout:
If proof of flame is not established, a component failure occurs or blockages are evident,
the heater will enter hard lockout. If lockout occurs, the control can be reset by briefly
interrupting the power source. Refer to Charts 4.1 and 4.2 on page 51 for a description
of LED codes.
Externally located operational indicator lights are provided to assist in troubleshooting of the heater.
Refer to page 52 for additional troubleshooting.
4.0
Operation
•
Sequence of Operation
WARNING
!
This heater must be installed and serviced by trained gas installation and service
personnel only.
Do not bypass any safety features or the heater’s built in safety mechanisms will be
compromised.
