Submittal Sheet
CAC-24 Combustion Air Control
Installation Instructions
This kit is designed to control more than one appliance on a system using the Field Controls CAS-4
Combustion Air System with a chimney vented gas fired system. The controls in the CAS-4 will
operate only one appliance, therefore a CAC-24 is required for each additional appliance to be added
to the same CAS-4 unit. One CAS-4 unit can handle at max, a total combined firing rate input of up to
500,000 BTU/Hr. Refer to the instructions included with the CAS-4 for more details and other
restrictions.
Items Included In Kit:
1) Junction box with mounted fan proving switch and relay base
1) 24 VAC relay
1) Conduit connector
1) 10 Ft. length of 1/4 inch plastic tubing
1) Plastic Tee
Mounting Junction Box:
The junction box may be mounted anywhere that is convenient for routing the wiring and tubing.
Mount the CAC-24 to a wall or floor joist using the four dimpled locations on the base of the box (See
Figure 1.)
Note: The unit must be mounted so the draft proving switch is vertical as shown in Figure 1. The
CAC-24 should be placed close enough to the CAS unit to route the provided 10 foot long plastic
tubing from the draft proving switch to the exposed tubing on the CAS. If mounting further away, the
installer must provide any necessary fittings and extra tubing.
Wiring:
Wire the controls in accordance with the National Electrical Code, manufacturer’s recommendations
and/or applicable local codes. UNIT MUST BE GROUNDED. Check ground circuit to make certain
that the unit has been properly grounded. The wiring should be protected by an overcurrent circuit
device rated at 15 amperes. CAUTION must be taken to insure that the wiring does not come into
contact with any heat source. All line voltage circuits MUST be wired in accordance with the National
Electrical Code for class one wiring or equivalent methods.
1. Remove one knockout from the junction box on the fan proving switch side. Install line voltage
power supply wires to the CAS unit as shown in Figure 1.
2. Remove one knockout from the side of the junction box opposite the fan proving switch. Run
24 VAC wiring to the appliance controls as shown in Figure 1. Refer to the appropriate gas
system configuration diagram for your specific appliance.
3. Insert the 24 VAC relay into the base on the CAC-24 and secure with the retaining clip.
4. Install the junction cover and secure with the 4 provided sheet metal screws.