installed in Canada. Install a separate 120 volt 15 amp circuit for the boiler. A properly rated shut-off switch should be located at the boiler. The boiler must be grounded in accordance with the authority having jurisdiction, or if none, the latest revision of the National Electrical Code, ANSI/NFPA-70.
Line voltage field wiring of any controls or other devices must use copper conductors with a minimum size of #14 awg. Low voltage wiring must not be less than #18 awg with a neoprene, thermoplastic or other equivalent insulation having a minimum insulation thickness of 0.012 inches.
Refer to Figures 19A and 19B for proper wiring connections.
Thermostat Installation
ALWAYS follow the instructions included with the ther- mostat to be used to control the boiler. Proper location of the thermostat will ensure efficient trouble-free operation of the boiler. Mount the thermostat to an inside wall at a height approximately five feet above the floor. Avoid placing the thermostat in areas that will not pro- vide an accurate measurement of the room temperature. Locating the thermostat behind a door, in an alcove, close to a source of thermal radiation or in a drafty area will cause poor or sporadic heating.
OPERATIONAL SEQUENCE
The control energizes the circulator motor when the thermostat contacts are closed. The control then checks that the limit switch is closed, if not the control will wait for the limit switch to close. With the limit switch closed the pressure switch contacts are checked. If the pressure switch contacts are open the blower motor is energized. If the pressure switch contacts aren’t open the control will wait 45 seconds then lock out. The PURGE light will flash to indicate a pressure switch fault. Also, if the pressure switch does not close within 5 minutes of the blower being turned on, the control will lock out with the PURGE light flashing to indicate a pressure switch fault.
The pre-purge period begins when the pressure switch contacts close. At the end of the pre-purge period, the control energizes the HSI igniter for an HSI warm-up period. This condition will be indicated by illumination of the IGNITER light. A one second trial for ignition will take place. In the event ignition is not achieved by the end of the first trial for ignition period, the control will run through a post purge and then de-energize the inducer. When the pressure switch contacts open the control will begin a new ignition sequence. Failure to establish flame after the third attempt will result in ignition lock-out and the VALVE light on the control will flash.
Once the flame has been proven, the system is in Steady-State heating mode. The control will continuously monitor the thermostat, limit switch, pressure switch, and flame sense. If the thermostat opens, the control will de-energize the gas valve and begin post-purge. If the limit switch opens, the control will de-energizes the gas valve, run through post-purge, and wait for the limit switch to re-close before attempting re-ignition. If flame is lost, the control will de-energize the gas valve, run through post-purge, and go to pressure switch proving mode for re-ignition. If the pressure switch opens for more than 0.1 seconds the inducer is turned off for 30 seconds, then the control goes to the pressure switch proving mode for a re-ignition attempt.
When the thermostat is satisfied the post purge period starts. A post-purge will be performed at any time the gas valve has been on and is turned off, except for loss of pressure switch, when a post-purge would be ineffective. The post-purge must be completed before a new ignition sequence can start.
In the event that the flame signal is lost after the flame has been proven, the system will turn off the gas valve within 2.0 seconds, perform the post-purge, and repeat the ignition sequence. As a preventative measure to avoid nuisance shutdown due to a flickering flame, the flame must be lost for a minimum of 0.5 seconds.
Control Outputs:
Induced draft blower - 1.75 Amps @ 120 VAC.
Circulator Pump - 2.7 Amps @ 120 VAC.
Hot Surface Igniter - 5.0 Amp resistive @ 120 VAC.
Gas Valve - 0.6 Amp @ 24 VAC, 0.45 power factor.
