Aprilaire 8556 - Manual (Page 29)

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Using The Available LED Indicators
This model is equipped with 2 LED indicator lights. These LEDs are located along the top edge of
the thermostat panel (not on the display) and look like small, clear edges protruding out of the top of the
thermostat. When the left and/or right LED is supplied with a 24 VAC signal, the LEDs glow red and can
be used to indicate many other system functions such as when the humidifier or fresh air exchanger is
running. Contact your installing contractor to understand what the left and/or right LEDs signal.
Use of left and right LEDs will require equipment and additional wiring at the thermostat which should
only be done by a qualified heating and cooling contractor.
In Case Of Power Failure
The Model 8556 thermostat does not require a battery. If the power goes out the letters “AC” appear on
the display indicating power is not being supplied to the thermostat. “AC” will remain on the display for
up to approximately 1 hour after the power goes out. During the period that the power is off, the
heating/cooling system will not operate.
110-791B 7/12/01 8:58 AM Page 29