Aiko CTH3-200, CTH3-150 Operation and Maintenance, Sequence of Operation, To Shut Off Heater

CTH3-SERIES INSTALLATION, OPERATION AND SERVICE MANUAL

SECTION 11: OPERATION AND MAINTENANCE

DANGER		WARNING
Electrical Shock Hazard	Explosion Hazard	Burn Hazard	Cut/Pinch Hazard
Disconnect electric	Turn off gas supply to	Allow heater to cool	Wear protective gear
	heater before service.	before service.	during installation,
before service.
			operation and service.
Heater must be		Tubing may still be hot
connected to a properly		after operation.	Edges are sharp.
grounded electrical
source.

Failure to follow these instructions can result in death, electric shock, injury or property damage.

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 maximum 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

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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 device to lowest setting. Turn OFF electric power to heater.

Turn OFF manual gas valve in the heater supply line.

11.3 To Start Heater

Turn gas valve and electric power OFF and wait five minutes for unburned gases to vent from heater.

Turn ON main gas valve.

Turn ON electric power.

Set heat demand device to desired temperature. Burner should light automatically.

11.4Pre-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.

Turn off gas and electric supplies before performing