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CTH3-SERIES INSTALLATION, OPERATION AND SERVICE MANUAL
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SECTION 11: OPERATION AND MAINTENANCE
11.1 Sequence of Operation
The control inside the heater's control compartment
is equipped with a tri-color LED. The LED offers
comprehensive diagnostic capability. The LED
status will be referenced throughout this section.
1. When the control is powered and there is no call
for heat from external heat demand device, the
LED on the control flashes slow green; LED is
ON for the same period it is OFF.
2. On a call for heat from the heat demand device,
the heater will go to PRE-PURGE. The LED
indicates one green flash. The blower speed will
vary as the pressure switch setpoints are
verified. When the PRE-PURGE is successfully
completed, the heater will go into the
PRE-IGNITION state and power the hot surface
igniter (H.S.I.).
3. After the igniter warms up, the heater will go to
the IGNITION state. Power is supplied to the
gas valve operator, gas flows, ignites and the
flame is proven. The LED shows two green
flashes on the LED. If a flame is not sensed, the
heater will RETRY, See Item 6 below for further
details.
4. When the IGNITION state is completed, the
heater will go to WARM UP state. The unit will
fire at maximu m input for 15 seconds. When the
WARM UP state is completed the device will go
into RUN state. The control board will monitor
the heat demand device and modulate the
heater input to meet the demand. The LED still
shows two green flashes.
5. When the call for heat has been satisfied, the
heater closes the gas valve. The blower
continues to run for a 45 second post-purge
period. After the post-purge, the heater turns
OFF and the LED on the control board flashes
slow green.
6. If flame is lost at any time during heater
operation, the heater will RETRY for ignition.
Upon RETRY the LED shows a fast yellow flash
(LED rapidly flashes). The heater will RETRY for
ignition three times. After four ignition attempts,
the heater will lockout for one hour or until reset.
To reset the heater, remove power for 10
seconds, then re-apply power. Turn heater ON
with call for heat from the heat demand device.
11.2 To Shut Off Heater
Set external heat demand dev
ice to lowest setting.
Tu rn OFF electric power to heater.
Tu rn OFF manual gas valve in the heater supply line.
11.3 To Start Heater
Tu rn gas valve and electric power OFF and wait five
minutes for unburned gases to vent from heater.
Tu rn ON main gas valve.
Tu rn ON electric power.
Set heat demand device to desired temperature.
Burner should light automatically.
11.4 Pre-Season Maintenance and Annual
Inspection
To ensure your safety and years of trouble-free
operation of the heating system, service and annual
inspections must be done by a contractor qualified in
the installation and service of gas-fired heating
equipment.
Tu rn off gas and electric supplies before performing
Cut/Pinch Hazard
Wear protective gear
during installation,
operation and service.
Edges are sharp.
WARNING
Failure to follow these instructions can result in death, electric shock, injury or property damage.
Burn Hazard
Allow heater to cool
before service.
Tubing may still be hot
after operation.
Explosion Hazard
Turn off gas supply to
heater before service.
DANGER
Electrical Shock Hazard
Disconnect electric
before service.
Heater must be
connected to a properly
grounded electrical
source.