FloAire Modular Packaged Unit - Manual (Page 14)

14
Sequence of Operation-Cooling with Direct, Indirect, or Electric Heat
This unit is most easily understood when broken down into smaller individual systems. There are two
main systems, a make-up air (MUA) fan and a cooling system. The make-up air fan consists of a blower
and motor. The cooling system consists of a condenser(s), DX coil, filter/dryer, and thermal expansion
valve.
Basic cooling units include 2 thermostats for proper operation. The first thermostat is an intake air
thermostat that prevents heating and cooling from occurring simultaneously. This is typically labeled
“Burner ON/Off Intake Air Thermostat.” This thermostat will allow the burner to operate when the outside
air temperature falls below the set point and prevents the burner from operating when the outside air
temperature rises above the set point. It also allows the cooling circuit to receive power when the outside
air temperature rises above the set point. This thermostat is typically set at 45° F and is adjustable.
The second thermostat is a cooling thermostat. The cooling thermostat allows the cooling circuit to
energize when the outside air rises above the set point. This is a 2 stage, differential thermostat; one set
point that energizes where the thermostat is set and a second stage that energizes at a factory setting of
10° F higher. The main set point controls the first stage of cooling and the differential controls the second
stage of cooling. This thermostat is factory set at 85° F; the factory setting and subsequent differential
setting are both adjustable.
With the blower already running and the airflow switch proven;
The air temperature rises above the setting of intake air thermostat and the cooling
thermostat
OR
The optional remote panel is set to “Manual” and “Cool” mode, and the temperature rises
above both thermostats as mentioned above.
•
The first stage condenser energizes and cooling starts.
•
The air temperature continues to rise above the cooling thermostat differential and the second stage
of cooling (if equipped) is energized.
•
Once the air temperature falls below the differential, the second stage of cooling is de-energized.
•
Once the air temperature falls below the cooling thermostat set point, both stages of cooling are de-
energized.
Cooling Thermostat on Left, Burner/Heat Thermostat on Right
***AN OPTIONAL PROGRAMMABLE THERMOSTAT
IS AVAILIBLE. WHEN THIS IS PROVIDED, AN AS
BUILT SCHEMATIC AND A SEPARATE MANUAL IS
PROVIDED FOR THE THERMOSTAT***