Operation summary – FloAire INDIRECT FIRED BENT TUBE MODULE User Manual
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A306 Outdoor Sensor
Use the installation instructions shipped with the A306 outdoor sensor.
Building Signal Damper Control
When this option is ordered, the supply and return dampers will modulate based on a 0-10 VDC signal
from the Building automation system.
Operation Summary
Main Blower is turned “On” and the Main Airflow Switch is proven.
Air temperature at the intake of the unit falls below the setting of the Intake Air Thermostat sending
24Vac power “Call for Heat” to FSC-1 and FVFAB.
FSC-1 sends 120Vac power to the line input of the Power-vent Blower Speed Controller.
Air temperature at discharge of the unit falls below the setting on the Temperature Selector Dial.
Power-vent Blower Speed Controller is controlled by the 10Vdc input signal from FVFAB and sends a
120Vac signal to Power-vent Blower Motor to initiate 1 min pre-purge at high speed.
24Vac signal runs through the safety circuit (Power-vent Airflow Switch/High Temperature
Limit/Flame Roll-out Switch) and into FSC-1.
FSC-1 initiates Trial for Ignition by sending signal to Spark Igniter to light furnace and 24Vac power to
On/Off Gas Valve and signal to FVFAB that it is sparking. This opens On/Off Gas Valve and triggers
the start of the 17 seconds of 10 VDC from the FVFAB to the Power-vent Blower Speed Controller(s)
and modulating valve(s).
Flame is sensed by FSC-1’s Remote Flame Sensor at the upper-most firing tube of furnace.
FVFAB’s 17 second high-fire off-delay time sequence runs out and 0-10Vdc modulating signal from
FVFAB is output to Modulating Gas Valve and Power-vent Blower Speed Controller.
FVFAB continues to modulate the heat output of MAU by adjusting the 0-10Vdc signal to Modulating
Gas Valve and turning other modulating furnaces or On/Off Staged Furnaces on and off as required
to satisfy the Temperature Selector Dial setting.
Note: If two modulating furnaces are present this sequence occurs with FSC-2 and a second speed
controller if the call for heat dictates a need for a second furnace.