Sterling TF-175, TF-400, TF-150, TF-300 Operation, Explanation of Controls See Figure, Shut Down

OPERATION

POWER VENTED PROPELLER UNITS

DIRECT SPARK IGNITION

EXPLANATION OF CONTROLS (See Figure 10):

1.The unit heater is equipped with a power vent system that consists of a power venter motor and blower, pressure switch, and sealed flue collector in place of the conventional draft diverter.

2.The power venter motor is energized by the room thermostat through the integrated control board when a demand for heat is sensed. The pressure switch measures the flow through the vent system and energizes the direct spark ignition system beginning the pre-purge timing when the flow is correct.

The pressure switch MUST NOT be bypassed. The unit MUST NOT be fired unless the power venter is operating. An unsafe condition could result.

3.The direct ignition system consists of an ignition control module and a gas valve. When the pre- purge period ends, the spark ignition system is energized, and the gas valve opens to supply gas to the burners. When the thermostat is satisfied, the vent system is de-energized and the valve closes to stop the flow of gas to the unit.

4.The limit switch interrupts the flow of electric current to the control board, interrupting the flow of gas to the gas valve if the unit heater becomes overheated.

5.Once the thermostat is satisfied, or the limit switch interrupts the flow of electric current to the control board, the unit will begin a post-purge period. When the post-purge period ends, the power venter motor is de-energized.

6.The fan operation is delayed 30 seconds once the thermostat is closed, and continues operation for 30 seconds after the thermostat opens.

NOTICE: The start-up fan delay must not exceed 30 seconds from a cold start.

7.The wall thermostat, supplied optionally, is a temperature sensitive switch that operates the vent and ignition system to control the temperature of the space being heated. The thermostat must be mounted on a vertical, vibration-free surface free from air currents and in accordance with the furnished instructions (also refer to Electrical Section).

START-UP (Also refer to lighting instruction plate equipped on the unit)

1.Open the manual gas valve in the gas supply line to the unit heater. Loosen the union in the gas line to purge it of air. Tighten the union and check for leaks.

Never use an open flame to detect gas leaks. Explosive conditions may exist which could result in personal injury or death.

2.Open the manual valve on the unit heater.

3.Turn ON the electrical power.

4.The unit should be under the control of the thermostat. Turn the thermostat to the highest point and determine that the power venter motor starts and the burners ignite. Turn the thermostat to the lowest point and determine that the power venter motor shuts off and the burners are extinguished.

5.Turn the thermostat to the desired position.

6.See Gas Input Rate and Adjustments sections.

SHUT DOWN

1.Turn the valve selector lever to the “OFF” position.

2.Turn off the electricity.

3.To relight, follow “start-up” instructions.

See Figures 10-17 for parts/identification.

Figure 10

17