General System Operation; Installation Safety Instructions - Field Controls 46401800 Instruction Sheet

GENERAL SYSTEM OPERATION

1. The thermostat (wall thermostat, or aquastat) calls for heat and energizes a relay which activates
the CAS unit. After the CAS fan has come up to speed, an internal air pressure switch closes and
completes the circuit to allow the burner to fire. If the appliance is power vented, the venter and
CAS activate simultaneously. After the CAS comes up to speed, a pressure switch in the unit
closes and allows the appliance to fire.
2. After the heating requirement has been satisfied, the thermostat circuit will open and deactivate
the burner and CAS unit.
3. For power vented systems with a post purge device, the power venter and CAS operate for a
period of time after the burner has shut off to purge remaining flue gases from the vent system.

INSTALLATION SAFETY INSTRUCTIONS

CAUTION: This device must be installed by a qualified installer in accordance with the manufacturer's
installation instructions.
1. This combustion air system must be installed by a qualified installer. "Qualified Installer" shall
mean an individual who has been properly trained or a licensed installer.
2. Plan the system layout before installation to avoid the possibility of accidental contact with
concealed wiring or plumbing inside walls.
3. Disconnect power supply before making wiring connections to prevent electrical shock and
equipment damage.
SIZING AND SETUP
Diagrams A and B and Table 1 shows the maximum equivalent length and size of duct pipe that
should be used when installing the CAS system. Using these charts will help ensure that the proper
amount of air is drawn into the structure as needed by the appliance. The defined regions shown
correspond to the CAS's airflow characteristics when using 4" and 6" diameter sheet metal duct pipe
and the included orifice ring. Follow the guidelines below to properly size and setup the CAS.
1. Determine the input firing rate of the appliance, or the total firing rate of multiple appliances that
will be used.
2. Position the motorized CAS unit according to the guidelines in the "Installation" section.
3. Determine where the intake air vent hood will be located based on the recommendations in the
"Installation" section.
4. The CAS is equipped with a High/Low motor speed control switch.
maximum equivalent feet, determine which speed is appropriate for the application. (Refer to
Diagram A or B or Table 1)
5. Calculate the total equivalent length of duct pipe including elbows and fittings needed to connect
the CAS unit to the vent hood. (Refer to Diagram A or B or Table 1)
6. On Diagram A or B, locate the point that corresponds to the firing rate along the horizontal axis
and the equivalent length of the duct pipe along the vertical axis, if using for make up air.
7. The point should fall within one of the three regions on the table. Each region corresponds to a
duct pipe diameter of 4", 4" using the orifice ring, and 6" respectively. If the point falls near the
rightward border of a particular region then the VRV is not necessary. If the point falls away from
the rightward border, then a VRV is needed to reduce the amount of air drawn in.
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When calculating the