Step 11: System Check Out; Troubleshooting Procedure - Aprilaire 8120 Safety & Installation Instructions

Step 7C
CFM Required >>
Step 8C
CFM Delivered
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STEP 11: SYSTEM CHECK OUT

A. For system test be sure that 24 VAC is applied in series with the 6506 damper (normally closed) and the A/A terminals on the Vent Control.
Check the wiring as described in Step 6.
B. Turn knob on Control dial to TEST position. If the installation is correct the blower will turn on (independent of heat or cooling operation)
and the damper will open. The vent system will operate for 1 minute unless the knob is turned off of TEST. If system does not operate in the
TEST Mode check the Troubleshooting Guide.
C. Return knob to the calculated setting. Do not leave in TEST, the Vent Control won't operate normally.
TROUBLESHOOTING
PROBLEM
HVAC Blower doesn't turn on
in Test Mode.
Damper does not open
in Test.
The Vent Control doesn't
turn off after the knob is
turned off Test.
The damper does not open
with the blower operating.
Blower turns on unexpectedly.
P.O. BOX 1467 • Madison, WI 53701-1467 • Phone: 800/334-6011 • Fax: 608/257-4357 • www.aprilairecontractor.com
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KNOB SETTINGS (in minutes) FOR AIRFLOW DELIVERED vs AIRFLOW REQUIRED (1 HR CYCLE)
20 30 40
15 20 30
15 20 25
10 15 20
10 15 15
10 10 15

TROUBLESHOOTING PROCEDURE

1. Make sure you turned the power back on to the HVAC equipment.
2. Check the wiring diagram for the R, C, W and GSTAT and GHVAC at both the HVAC equipment and the Vent Control.
3. Make sure the Outdoor Sensor Terminals on the Control are connected with either the Temperature Sensor, the Time
Only Insert or a jumper wire. If nothing is connected here the Control will not function.
4. Check voltage across the Vent Control R&C terminals. Voltage should be in the 22 VAC to 30 VAC range.
5. Remember, once the Test minute is up the system won't operate.
1. Follow above procedure.
2. Check wiring diagram to make sure the damper is wired in series with the circuit board and transformer.
1. This might be okay, the thermostat might have activated. Also the blower might be set up for continuous operation.
The Vent Control should deactivate once the time setting is reached.
2. If the pins are set to 1 hour and the knob is turned to 60 minutes the Vent Control will not turn off. But for a 2 hour
pin setting, if the knob is at 60 minutes, at the end of that 60 minutes the Vent will turn off.
1. The damper will not operate once the time interval has been met. If the knob is turned to 5 minutes and 5 minutes
has elapsed, the damper will close and it will stay closed until the pin setting interval is met.
2. If the Indoor RH is above 55% and the outdoor temperature is above 50° the damper will not open because of the
potential for excess humidity.
3. If the outdoor temperature is below 0° or above 100° the vent stays off.
4. Verify that the outdoor temperature sensor is located within 3 feet of the vent inlet, or if located outside that it's not
in direct sunlight at any time.
5. Turbulence in the return duct, plenum or mixing box can give false readings. Make sure the Vent Control is at least
6 inches upstream of the fresh air intake port in the return to minimize this effect.
1. The Vent Control will activate the blower whether or not heat or A/C is on call. This ensures ventilation even if the
thermostat is lowered.
2. To verify proper operation see if the blower turns off by turning down the knob. Return to its original setting.
RESEARCH PRODUCTS CORPORATION
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