Tjernlund UCRT Rooftop Inducer Universal Control (Version X.06) 8504162 Rev A 05/11 - Manual (Page 15)

* Investigate cause of Fan Prover short cycling such as; firing burner at capacities or temperatures exceeding Inducer limits,
excessive vent pipe runs, high winds, plugged / kinked Fan Prover sensing tube. PSA-1 Fan Prover may be faulty or setpoint
may be too high and need adjustment.
SYMPTOM 1: INDUCER OPERATES CONTINUOUSLY
Verify that Inducer is not in post-purge mode which could last up to 16 minutes. A factory post-purge has been set for 2 minutes.
LED #4 & #5 (Red) will flash in unison during post-purge. An Inducer pre-purge could also be set for up to 35 seconds. LED #4 &
#5 (Red) will flash alternately during pre-purge. See “Pre / Post-Purge Settings” on page 3.
Verify that LED #1 (Amber) is not lit.
Yes, LED #1 (Amber) is lit: Check interlock wiring. Confirm burner control(s) are functioning properly. UC1 control is receiving
constant call for heat signal.
LED #1 (Amber) is not lit: Replace UC1 circuit board part number 950-8804.
SYMPTOM 2: INDUCER MOTOR DOES NOT OPERATE
Verify that UC1 control has power, LED #6 (Red) should be lit. Verify that LED# 4 (Red) is not flashing. See “LED Status & Fault
Indicators” above if flashing. Verify RED voltage selection jumper corresponds with interlock voltage (i.e 24V, 115V or “Dry”).
No: Check circuit breaker, disconnect switches and wiring.
Yes, LED #6 (Red) is lit: Verify that the interlocked burner is calling for heat, LED #1 (Amber) should be lit.
No, LED #1 (Amber) is not lit: Verify interlock wiring and that thermostat/aquastat is adjusted to call for heat. Verify that the RED
voltage selection jumper is installed so that it matches the voltage of the interlocked burner.
Yes, LED #1 (Amber) is lit: Verify Prover safety circuit fault does not exist. See, “LED Status & Fault Indicators” on page 13.
If faults exist check Prover P1 & P2 safety circuit. “PSA-1 Fan Proving Switch Adjustment” on page 12 may need to be performed
again.
If no faults exist, check for 115 VAC across terminals N and MTR.
Voltage present: Confirm motor speed control is switched ON and check for voltage in UCRT across Red from speed control and
White or Neutral.
No voltage present from speed control: Replace UCRT Speed Control part number 950-8601.
Voltage present from speed control: Confirm voltage is present across Red & White or Neutral lead in Rooftop Inducer 4x4 weatherproof
junction box.
Voltage present: Inducer capacitor or motor may be defective.
SYMPTOM 3: INDUCER OPERATES, BUT BURNER DOES NOT
For any newly established call for heat the Inducer will run for 60 seconds to try to close the UC1 Fan Prover circuit (P1 to P2). If
circuit can not be made within 60 seconds LED #4 (Red) will flash 3 times, indicating a prover check circuit fault on UC1 start up.
NOTE: The UC1 safety circuit and LED #4 (Red) will be reset if the call for heat interlock signal or 115 VAC power is removed. If
the fan prover makes on start up, but breaks for more than 10 seconds during the burner cycle, LED #4 will flash continuously indi-
cating a prover circuit fault. The Inducer will continue to run for 10 minutes to try to make the prover circuit as long as a call for
heat exists. If Prover does not make within 10 minutes, the UC1 will shut down and LED #4 (Red) will flash 4 times indicating a
prover circuit fault. Remove the call for heat and then reestablish to reset the UC1 prover safety circuit (P1 to P2) & LED #4 (Red).
Verify that LED #2 (Blue) is lit.
Yes, LED #2 (Blue) is lit: Verify that "call jumper" is connected from J1 to J2 on UC1 circuit board if using typical wiring where sup-
ply voltage from terminal 1 is routed to terminal 3 through “call jumper” then to 4 when appliance interlock relay makes. With call
for heat established, verify that wiring is correct by measuring voltage between terminals 1 & 2 and 2 & 4 of UC1 terminal strip.
Voltage should be the same in both cases, if not rewire per appropriate diagram or confirm burner control(s) are functioning prop-
erly. NOTE: If outside power source is provided to terminal 3 and switched to terminal 4 check for continuity between 3 and 4
with leads disconnected from 3 and 4 and Inducer operating. If there is no continuity between 3 and 4 and the Blue LED is lit,
replace UC1 circuit board part number 950-8804. If continuity is present, recheck interlock wiring and burner control(s). If using the
A-B dry contacts for millivolt installations make sure system Linear Limit Spillage switch on draft hood/diverter has not tripped.
Reset and relight pilot if necessary.
No, LED #2 (Blue) is not lit: Remove power from UC1 and confirm dip switch #9 is up or “on” to deactivate the Pre-Cycle Fan
Prover status check. Keeping the Pre-Cycle Prover Status Check activated may cause nuisance lockouts. Remove P1 and P2
prover leads off of PSA-1 Fan Prover switch and jumper together. Reestablish power and call for heat. After Inducer pre-purge, if
set (Adjustable from 0 to 35 seconds), LED #2 (Blue) should light.
No, LED #2 (Blue) does not light: Replace UC1 circuit board, part number 950-8804.
Yes, LED #2 (Blue) lights up: The PSA-1 Fan Proving switch may not be closing, wiring connections are incorrect/broken or burner
control(s) are not functioning properly. With Inducer running, verify that Inducer performance is sufficient to close Fan Prover con-
tacts by checking for continuity across switch. Replace PSA-1 Fan Prover leads from P1 and P2 back on Fan Proving switch.
IMPORTANT: Fault codes will automatically be displayed after a fault condition occurs. If the call for heat interlock sig-
nal or 115 VAC power is removed, the UC1 board will reset and the fault will be stored in memory instead of displayed.
Any new fault will replace any previous fault.
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