Aprilaire 8126A, 8120A User Manual
Model 8120A & 8126A
Digital Ventilation Controller
Owner’s Manual
Includes Safety &
Operating Instructions and
Warranty Information
READ AND SAVE THESE INSTRUCTIONS
SETTING INSTRUCTIONSPRINCIPLES OF OPERATION
Today’s houses are constructed using “Green” techniques and energy saving systems. These practices and
innovations help reduce your utility bills, but prevent the introduction of fresh air. Without ventilation, stale air and
contaminants from cleaning, painting, and exhaust from attached garages can remain in the air for extended periods
of time. Your Aprilaire ventilation controller brings in fresh air and circulates it through your home around the clock
to help reduce the stuffy effects of trapped stale air. The actual rate of ventilation is determined by the size of your
home and the number of occupants. With your investment in the ventilation controller, you have a dependable way of
automatically providing fresh air to your home. The controller continuously monitors indoor humidity, along with the
outdoor temperature, and operates according to the timer settings as adjusted to your preference, local codes, or the
HVAC industry recognized ASHRAE 62.2-2010 guidelines. The ventilation controller will not let outside air enter if it
could potentially raise the humidity inside to high levels. To prevent this, the ventilation controller has an upper limit
of 55% RH when the outdoor temperature is above 50°F. The ventilation controller can also prevent ventilation in
extreme high or low temperatures. See your installing contractor to enable or disable these limits.
Please Note: Ventilation will not occur if the inlet is clogged with debris. Clean this regularly.
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Your ventilation controller is installed in the return duct of your furnace or heat pump. There is one user adjustable
setting, the ventilation time per hour. For example, if the controller knob is set to 20 minutes, you will get 20 minutes
of ventilation every hour. Ventilation occurs during heating and cooling calls. If the heating or cooling system does
not initiate ventilation, the controller will turn on the furnace blower to provide the 20 minutes.
• The dial is labeled in 10 minute increments, but can be set to
any estimated value within 5 minute accuracy. The installer
will have already set this for you according to the size and
number of occupants for your home. If you feel like you need
more or less time, turn the knob a maximum of 5 minutes
either way. Allow ventilation at the new setting to operate
for 24 hours before adjusting.
• The TEST/RESET setting is used to check the device for
proper installation. This setting will only activate the
controller for 1 minute. Do not leave the knob at TEST/RESET.
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