Tjernlund HSJ, 1, 2 Series with UC1 Universal Control (Version X.04) 8504106 Rev B 05/03 - Manual (Page 11)

UC1 UNIVERSAL CONTROL INSTALLATION AND MOUNTING
The UC1 has a 2 foot whip that contains a ground lead and the leads to power the Venter motor and connect to the Fan Prover. If it
is desirable to mount the UC1 more than 2 feet from the Venter an additional electrical junction box and appropriate length of conduit
will be necessary. Any added wire should be 14 gauge and a pig tail should be added to each ground wire connection so that each
electrical junction box is grounded.
Do not mount the UC1 junction box on a heat source that exceeds 140oF (60oC). Examples of improper mounting surfaces include
vent pipe, top of heater casing or any place where radiant or convective heat would cause the junction box temperature to exceed 140oF.
The UC1 is intended for indoor installation only.
Using the key hole slots on the back of the UC1 junction box as a template, mark 4 holes on the mounting surface, drill pilot holes if
necessary, and secure junction box using provided screws.
ELECTRICAL WIRING
All wiring from the UC1 to the appliance must be appropriate Class 1 wiring as follows: installed in rigid 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.
SEQUENCE OF OPERATION WITH UC1 UNIVERSAL CONTROL AND 24 VAC OR 115 VAC HEATER CONTROL CIRCUIT:
Control signal from thermostat, aquastat, primary control or gas valve is intercepted and routed to terminal “1” on UC1 terminal strip.
When terminal “1” is energized with either 24 VAC or 115 VAC, the Venter motor is energized. After draft is established, the Fan
Proving Switch closes within 5 to 10 seconds energizing terminal “4”, which completes the circuit allowing burner to fire. NOTE: If a
Venter pre-purge is selected, the burner will not fire until the pre-purge time is finished. The Venter will continue to run after the burn-
er has finished firing for the set post-purge time cycle. The UC1 is set for a 2 minute post-purge time period from the factory. See
“Pre / Post-Purge Settings” on page 5 for details.
The "1" input terminal on the UC1 can accept either a 24 VAC or 115 VAC control signal. IMPORTANT: The RED voltage
jumper must be positioned based on appliance interlock voltage 24V or 115V. If using the “DRY” contact activation method, use ter-
minals A & B on UC1 control and position the RED voltage jumper tab in the “DRY” position. See millivolt appliance interlock dia-
gram for further information. IMPORTANT: Only one interlock method (i.e. 24V, 115V or “Dry”) can be used with the UC1. Multiple
appliance interlocks require the use of our MAC-Series multiple appliance controls.
The steps listed under each diagram are intended as a supplement to the diagram. Wiring colors or designations may vary by manu-
facturer. If you are unable to wire the UC1 as outlined in these instructions, call Tjernlund’s Customer Service Department toll free at
1-800-255-4208 for assistance.
IMPORTANT: If the call for heat interlock signal or 115 VAC power is removed, the UC1 board will reset and any fault, if present, will
be stored in memory instead of displayed. See page 5, “Checking Memory for Last Fault Code”.
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(UPFLOW APPLIANCE)
IMPORTANT: MORE THAN ONE INTERLOCK METHOD MAY BE APPLICABLE
In many cases it is easier to interlock with the thermostat/aquastat portion of the heater control circuit vs. the ignition module /
primary control portion of the heater control circuit. Review all of the wiring diagram options prior to choosing the best method.