Tjernlund WHK-2 Millivolt Interlock Kit (Discontinued - Not Compatible with UC1) 8504026 Rev 8 09/98 - Manual (Page 8)

115 VAC INTERLOCK WITH HS115 - SERIES POWER VENTERS AND 115 VAC CONTROLLED DRAFT INDUCERS
1. Connect the GRAY wire from the WHK-2 Module to the BLACK 115 VAC motor lead of the Power Venter or Draft Inducer.
NOTE: Cut the quick connect and cap with wire connector.
2. Connect the WHITE wire from the WHK-2 to the WHITE wire from the Power Venter or Draft Inducer motor.
3. IMPORTANT: The BLACK wire from the WHK-2 module is not used in these applications. Cut stripped end of this wire and wrap
with suitable electrical tape to prevent contact with other live connections in wiring box.
NOTE: When using the HS115 for a water heater only, the YELLOW and BLUE wires in the Power Venter are not used.
WHK-2 WIRING
WHK-2 OPERATION
WHK-2 SEQUENCE OF OPERATION:
1. Water heater calls for heat which sends a small amount of gas from the water heater pressure tap to the Gas Pressure Switch.
2. Gas Pressure Switch closes completing the circuit between the WHK-2 Transformer and terminals 4 & 5 of WHK-2 Relay/Timer.
3. When terminals 4 & 5 of the WHK-2 Relay/Timer receive 24V, an internal switch of the WHK-2 Relay/Timer closes between L1 and
BLK. MTR. sending current to the Gray of the WHK-2 metal conduit.
4. When the water heater thermostat is satisfied the Gas Pressure Switch will open, disrupting 24V to terminals 4 & 5 of the WHK-2
Relay/Timer. The internal switch between L1 and BLK. MTR. of the WHK-2 Relay/Timer remains closed for an adjustable time
allowing the Power Venter/Draft Inducer to continue operating.
WHK-2 SAFETY OPERATION:
If the Venter fails to operate, flue gas spillage will occur from the water heater draft hood. The heat from the flue gas will cause the
Linear Limit switch to open, opening the circuit to the Solenoid Valve. The Solenoid Valve will close disrupting the gas supply to the
water heater.
OPERATIONAL NOTES:
The BLACK wire from the WHK-2 is always “hot” and is not used if venting a water heater only. If common venting two appliances,
the venter will only post purge with the water heater.
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