FloAire INDIRECT FIRED BENT TUBE MODULE - Manual (Page 29)

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Components
The following image and list outlines the typical in-direct fired heater components and their functions.
1. Main Disconnect Switch – Controls all electrical power to entire unit.
2. Circuit Breaker – Protects electrical components from high current spikes.
3. Terminal Strip – Central location to terminate control wiring. Should be used for troubleshooting.
4. Motor Starter – Contactor with overload protection to start and protect motor.
5. Variable Frequency Drive (Optional) – Used in place of motor starter to protect main blower
motor and to control the speed of the main blower to vary main airflow across unit.
6. Control Transformer – 120V primary; 24V secondary control transformer.
7. Modulating Gas Valve Control Transformer – 120V primary; 24V secondary control
transformer. Provides standing 24V power to Modulating Gas Valve.
8. Main Airflow Switch – Senses that there is main airflow across the Heat-exchanger of the
furnace. Adjustable set-point. Heater circuit will not energize unless proven.
9. Intake Air Thermostat – Energizes Flame safety control for the modulating furnace and the
FVFAB controller if ambient temperature at intake drops below set-point. DOES NOT CONTROL
THE TEMPERATURE AT WHICH THE UNIT HEATS THE DISCHARGE AIR TO (COMPONENT
#11 USED FOR THIS PURPOSE).
10. FVFAB – Controls the 0-10 VDC signal to modulating furnace controls, modulating gas valve(s)
and speed controller(s) and 24 VAC signals to staged furnace controls. Works in conjunction with
component # 11.
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17A
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