COMBUSTION AIR SYSTEM
MODEL: CAS-4JR
This product is designed for use with any natural gas or LP burning furnace, water heater, or boiler with a
24 VAC control system. It may be used with a residential water heater with additional hardware. It may
also be used with more than one appliance. The CAS unit mechanically draws air into a structure and
disperses it near the combustion air intake of an appliance. Refer to Diagram A and Table 1 for guidance
in setting up the CAS system based on the size and length of the connecting ductwork and the input rating
of the appliance.
ITEMS INCLUDED IN KIT:
1- CAS fan unit
1- 4" galvanized intake Air Vent Hood
2- Mounting brackets to secure the CAS to a wall
2- Wire/conduit connector(s)
1- Instruction Sheet
READ THESE INSTRUCTIONS CAREFULLY AND COMPLETELY BEFORE PROCEEDING WITH THE INSTALLATION.
This device MUST be installed by a qualified agency in accordance with the manufacturer's installation instructions. The definition of
a qualified agency is: any individual, firm, corporation or company which either in person or through a representative is engaged
in, and is responsible for, the installation and operation of HVAC appliances, who is experienced in such work, familiar with all the
precautions required, and has complied with all the requirements of the authority having jurisdiction.
Please retain these instructions after installation.
Installed By: Phone:
www.fieldcontrols.com
Installation Date:
GENERAL SYSTEM OPERATION
The thermostat (wall thermostat, or Aquastat) calls for heat and energizes a relay which activates the CAS 1.
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.
After the heating requirement has been satisfied, the thermostat circuit will open and deactivate the burner 2.
and CAS unit.
For power vented systems with a post purge device, the power venter and CAS operate for a period of time 3.
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.
This combustion air system must be installed by a qualified installer. "Qualified Installer" shall mean an individual 1.
who has been properly trained or a licensed installer.
Plan the system layout before installation to avoid the possibility of accidental contact with concealed wiring or 2.
plumbing inside walls.
Disconnect power supply before making wiring connections to prevent electrical shock and equipment damage.3.
SIZING AND SETUP
Diagram A shows the maximum equivalent length and size of duct pipe that should be used when installing the
CAS system. Using the chart 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 airflow characteristics when using 4" and 6"
diameter sheet metal duct pipe. Follow the guidelines below to properly size and set up the CAS.
Determine the maximum input firing rate of the appliance, or the maximum total combined input firing rate of 1.
multiple appliances that will be used.
On Diagram A, locate the point that corresponds to the maximum total combined input firing rate along the 2.
horizontal axis.
Draw a vertical line through the point on the horizontal axis.3.
Draw a horizontal line through the point where the vertical line intersects the 4" duct pipe curve.4.
The horizontal line will intersect the vertical axis of the graph at the maximum allowable equivalent length of 5.
4" duct pipe, for the given firing rate.
Position the motorized CAS unit according to the guidelines in the "Installation" section.6.
Determine where the intake air vent hood will be located based on the recommendations in the 7.
"Installation" section.
Calculate the total equivalent length of duct pipe including elbows and fittings needed to connect the CAS unit 8.
to the vent hood. DO NOT add any equivalent length for the intake hood; the hood effect is figured into the
graph.
Using Table 1, verify that the calculated total equivalent length of pipe does not exceed the maximum length 9.
of 4" pipe as found in Step 5. If so, repeat Step 5, drawing a horizontal line where the vertical line drawn
intersects the next larger size duct pipe curve and verify from steps 6-8 that the total equivalent length does
not exceed that as found in Step 5 for the larger size duct pipe.
EXAMPLE:10. A gas fired appliance firing at 100,000 BTU/hr where the CAS unit needs to be placed 30
equivalent feet from the intake hood.
page 2
0
20
40
60
80
100
120
140
160
180
200
220
240
260
280
300
50,000 60,000 70,000 80,000 90,000 100,000 110,000
CAS-4JR SIZING CHART
Max. Equivalent Duct Length, feet
Input Firing Rate, BTU/hour
Max. equivalent length of 4" pipe
available when using the 4" CAS hood
Max. equivalent length of 6" pipe
available when using the 4" CAS hood
Table 1
TOTAL INPUT OF APPLIANCE MAXIMUM EQUIVALENT FEET OF DUCT PIPE
(BTU/hr) 4" Pipe 5" Pipe 6" Pipe
50,000 230 300 300
60,000 16 0 300 300
70,000 105 300 300
80,000 70 214 300
90,000 40 122 300
100,000 25 76 180
110,000 15 46 80
page 3
Diagram A
INSTALL ATION
PLACEMENT OF THE CAS UNIT
The motorized CAS unit should be located on a
flat horizontal surface within the same space as
the appliance and within 3' of the combustion air
intake. Two mounting brackets are provided for
securing the unit against a solid structure, such as
a wall, column, or the side of the appliance itself.
Use the included screws to attach the brackets to
the CAS housing as shown in Figure 1. Secure
the brackets to a solid structure with appropriate
fasteners. It is not required to use the brackets as
long as the unit is located so that it may not be
bumped, moved, or tipped over.
INTAKE AIR HOOD LOCATION
The 4" galvanized vent hood should be located
on an outside wall maintaining minimum
clearances to other intake and exhaust vents in
accordance with the National Fuel Gas Code,
ANSI Z223.1, manufacturer's recommendations
and/or local codes which are applicable.
The hood should be located at least 10' from
a power vented exhaust outlet and should be
on the same wall. The intake air hood should
be a minimum of 1' above grade or snow
lines where applicable.
Figure 1
INSTALLATION OF INTAKE AIR HOOD
After determining the location of the vent
1
hood, cut a 4
⁄2" round or square hole in
the wall. Insert the vent hood and secure
with appropriate fasteners. Take precautions
to avoid interference with wiring or other
plumbing in the wall to be cut.
INSTALLATION OF DUCT
Refer to Diagram A to determine what pipe is
needed. Connect the duct pipe from the top
of the CAS unit to the Vent Hood in the wall.
The duct should be supported with appropriate
mounting straps from floor joists, walls, or other
solid structures. The straps should be placed so
as to keep the duct work out of passageways.
(See Figure 2)
Figure 2
page 4
WIRING INSTRUCTIONS
Black
White
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Red
Red
Common
Common
Wire the CAS unit in accordance with the National Electrical Code and applicable local codes. UNIT MUST
BE GROUNDED. Check the ground circuit to make certain that the unit has been properly grounded. The
wiring should be protected by an over-current circuit device rated at 15 amperes. CAUTION must be taken
to ensure that the wiring does not come in contact with any heat source. All line voltage and control circuits
between the CAS unit and the appliance MUST be wired in accordance with the National Electrical Code for
Class I wiring or equivalent.
Remove the wiring access cover to access the wiring terminals. Use the included conduit connector(s) to route
the appropriate wires through the CAS housing. The incoming ground wire must be attached to the green
colored ground screw near the wire terminals. The following sections describe the most common applications.
The references to various series of control kits implies that any kit in that series may be used. If further
information or additional wiring diagrams are needed please consult Field Controls' technical support.
WARNING: To reduce the risk of fire or electric shock, do
not use this fan with any solid-state speed control device.
INTERNAL WIRING CONNECTIONS FOR THE CAS UNIT
Refer to Figure 3 for the internal wiring of the CAS-4JR unit.
EXTERNAL WIRING CONNECTIONS
Refer to Figures 4-9 for appropriate wiring method.
Figure 3
Figure 4 - Chimney Vent Single 24V Furnace
page 5
White
White
White
White
White
Black
Black
BlackBlack
Red
Red
Common
Common
Black
Black
Black
White
Red
Red
Common
Common
Figure 5 - Power Vent Single 24V Furnace
page 6
Figure 6 - Chimney Vent 24V Furnace and 30mV
Water Heater with CK-20FV or CK-20FG
Figure 7 - Chimney Vent 24V Boiler
Figure 8 - Power Vent Single 24V Boiler
page 7
Figure 9
LIMITED WARRANTY
Field Controls, LLC (“Company”) warrants that its products shall be free from defects in material and workmanship
under normal use for the limited period indicated, from the date of manufacture, subject to the provisions 1-8 below.
Eighteen (18) months
All Field Controls Products (except for those listed below as 5 years or 90 days).
Five (5) years
Field Controls Direct Vent Systems (FDVS), Field Oil Vent Kits (FOVP), and ComboVents (CV).
Field Controls warrants that the products listed below shall be free from defects in material and workmanship under
normal use for the limited period indicated, from the date of purchase by the consumer, subject to the provisions
1-8 below.
Ninety (90) days
UV lamps/bulbs
Provisions:
1. During the limited warranty period, Company, or its authorized service representative, will repair or replace, at Company’s
option, without charge, a defective Product. Product that is repaired may be repaired with new or refurbished replacement
parts. Product that is replaced may be replaced with a new or refurbished product of the same or similar design. Company
will return repaired or replacement Product to customer in working condition. Labor charges are not covered as part of the
limited warranty.
2. With regard to UV lamps/bulbs, customer shall be required to include a "valid proof of purchase" (sales receipt) identifying
the Product purchased (Product model or accurate date code information) and the date the Product(s) was purchased.
3. Product whose warranty/quality stickers, Product serial number plates or electronic serial numbers have been removed,
altered or rendered illegible shall not be covered under the limited warranty.
4. Defective Product must be returned to Company, postage prepaid.
5. IN NO EVENT SHALL COMPANY BE LIABLE FOR ANY INDIRECT, SPECIAL, INCIDENTAL, CONSEQUENTIAL, OR SIMILAR
DAMAGES (INCLUDING, BUT NOT LIMITED TO, LOST PROFITS OR REVENUE, INABILITY TO USE PRODUCT, OR OTHER
ASSOCIATED EQUIPMENT, THE COST OF SUBSTITUTE EQUIPMENT, AND CLAIMS BY THIRD PARTIES) RESULTING FROM
THE USE OF PRODUCT. Some states do not allow the exclusion or limitation of incidental or consequential damages, so the
above limitation or exclusion may not apply to you.
6. THIS WARRANTY AND REMEDIES ARE EXCLUSIVE AND IN LIEU OF ALL OTHER WARRANTIES, REMEDIES AND
CONDITIONS, WHETHER ORAL, WRITTEN, EXPRESS, STATUTORY OR IMPLIED. TO THE EXTENT PERMITTED BY LAW,
COMPANY DISCLAIMS ALL IMPLIED AND STATUTORY WARRANTIES, INCLUDING WARRANTIES OF MERCHANTABILITY
AND FITNESS FOR A PARTICULAR PURPOSE.
7. Company makes no warranty of any kind in regard to other manufacturer’s products distributed by Company. Company will
pass on all warranties made by the manufacturer and where possible, will expedite the claim on behalf of the customer, but
ultimately, responsibility for disposition of the warranty claim lies with the manufacturer.
8. Product that has been subjected to misuse, accident, shipping or other physical damage, improper installation or application,
abnormal operation or handling, neglect, fire, water or other liquid intrusion are not covered by the warranty.
MAINTENANCE
1. Inspect the system annually to ensure proper operation by observing that the fan activates when a call for heat occurs
and deactivates when the call for heat is satisfied.
2. Disconnect power to the CAS unit and repeat Step 1. Note: The unit should not run and the appliance should not fire in
this condition.
3. Inspect the duct pipe for cracks and security to the CAS unit and vent hood.
4. Clear any obstructions, if present, from the inlet of the vent hood and the outlet of the CAS unit.
5. Periodically, the fan blade chamber may need cleaning. First, disconnect the power supply to the CAS. Next, disconnect
the duct pipe from the unit. Then remove the top pan and clean the fan housing area as needed. Reattach the top pan,
reconnect the duct pipe and the power supply.
REPLACEMENT PARTS
The following items are available for replacement, if needed. In
order to replace these parts, power must be disconnected and the
unit must be partially disassembled. If this is necessary, take note
of the positions and locations of whatever items that may need to
be removed to replace other items. If in doubt, please consult Field
Controls Technical Support at 1-800-742-8368.
ITEM DESCRIPTION FIELD PART NUMBER
Motor, DI-1 4607010 0
Fan Blade Assembly 46528500
Air Pressure Switch 46525700
24 VAC Relay for CAS-4 4616140 0
4" Intake Hood 46252600
6" Intake Hood (not included) 46233300
© Field Controls, LLC P/N 46527900 Rev A 11/09
Phone: 252.522.3031 • Fax: 252.522.0214
www.fieldcontrols.com
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