Tjernlund HST_HS115_HSUL-JC, 1C, 2C Canadian Series (Discontinued) 8504017 Rev 1 09/97 - Manual (Page 9)

ELECTRICAL WIRING
WIRING RESTRICTIONS
1. All wiring from the Power Venter to the appliance must be appropriate class 1 wiring as follows:
Installed in rigid metal conduit, intermediate metal conduit, intermediate metal conduit, rigid non-metallic conduit, electrical metallic
tubing, Type MI cable, Type MC cable or be otherwise suitably protected from physical damage.
2. The electrical contact ratings for the diaphragm Fan Proving Switch are as follows:
3 amps (full load) at 120 VAC
28VA Pilot Duty (1.16 amps) at 24 VAC
125 VA Pilot Duty at 120 VAC
The Fan Proving Switch and Power Venter are not suitable for use with loads which exceed the above limitations.
TJERNLUND POWER VENTER SEQUENCE OF OPERATION
HSUL OR HST SERIES WIRED AT 24V GAS VALVE:
As the thermostat senses a need for heat, 24V is applied to the Power Venter relay. The 24 volts applied to the relay coil bring in the
115 volt power to the motor. The air movement generated by the Power Venter closes the Fan Proving Switch contacts which allow
the thermostat signal to reach the 24 volt gas valve. The Fan Proving Switch actually becomes the burner controller and will allow the
appliance to operate only when the thermostat is calling for heat and the Power Venter is operating. DO NOT OPERATE THE APPLI-
ANCE WITHOUT THE FAN PROVING SWITCH WIRED INTO THE 24V APPLIANCE CIRCUIT!
HSUL OR HST SERIES ALTERNATIVE GAS WIRING TO THERMOSTAT ON SINGLE ZONE FURNACE/BOILER INSTALLATIONS
As the thermostat senses a need for heat, 24V is applied to the Power Venter relay. The 24 volts applied to the relay coil bring in the
115 volt power to the motor. The air movement generated by the Power Venter closes the Fan Proving Switch contacts which allow
the thermostat signal to reach “W” on the 24 volt burner control. The Fan Proving Switch actually becomes the burner controller and
will allow the appliance to operate only when the thermostat is calling for heat and the Power Venter is operating. DO NOT OPER-
ATE THE APPLIANCE WITHOUT THE FAN PROVING SWITCH WIRED INTO THE 24V APPLIANCE CIRCUIT!
HS115 SERIES WIRED AT 115V GAS VALVE OR BURNER MOTOR:
As the thermostat senses a need for heat, 115V is applied to the Power Venter motor. The air movement generated by the Power
Venter closes the Fan Proving Switch contacts which allow 115V to be applied to the gas valve or burner motor. The Fan Proving
Switch actually becomes the burner controller and will allow the appliance to operate only when the thermostat is calling for heat and
the Power Venter is operating. DO NOT OPERATE THE APPLIANCE WITHOUT THE FAN PROVING SWITCH WIRED INTO THE
115V APPLIANCE CIRCUIT!
HST SERIES WIRED TO OIL BURNER:
As the thermostat senses need for heat, the internal switch of the thermostat closes. The switch closure sends a signal through the
appliance Cad Cell Relay to the Power Venter Relay/Timer and the Fan Proving Switch. The Relay/Timer is then energized bringing
the 115 volt power to the Power Venter motor. The air movement generated by the Power Venter closes the Fan Proving Switch con-
tacts which allow the 115V signal from the Cad Cell Relay to reach the burner motor. The Fan Proving Switch actually becomes the
burner motor controller and will allow the burner to operate only when the thermostat is calling for heat and the Power Venter is run-
ning. DO NOT OPERATE THE BURNER WITHOUT THE FAN PROVING SWITCH WIRED INTO THE BURNER CIRCUIT!
NOTE:
The following wiring diagrams are designed to satisfy most installations. Should your installation be different from those shown in
these instructions, please contact the Tjernlund Technical Service Department for assistance at 1-800-255-4208, 7:30 - 4:30 CST.
8
DISCONNECT 115 VAC POWER TO THE APPLIANCE BEFORE PROCEEDING WITH POWER VENTER WIRING. THE POWER
MAY BE DISCONNECTED BY TRIPPING THE CIRCUIT BREAKER OR REMOVING THE FUSE PROTECTING THE APPLIANCE.
ELECTRICAL CONDUIT AND 24 VAC WIRING MUST BE ROUTED AWAY FROM ANY HOT SURFACES. USE ADEQUATE CON-
DUIT SUPPORTS WHERE NECESSARY. ALL WIRING MUST COMPLY WITH APPLICABLE CODES AND ORDINANCES. ALL
115 VAC WIRING MUST USE RIGID OR SEMI-RIGID METAL CONDUIT WITH 18 AWG, 300 VAC, 90 DEGREE C-RATED COP-
PER WIRE.