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COMBUSTION AIR SYSTEM
Model: CAS-6, CAS-6SK, CAS-7, and CAS-7SK
This product is designed for use with any oil or gas fired furnace, water heater, or boiler with 24 VAC or
120 VAC control systems. It may also be used with millivolt water heaters and 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 Diagrams A & B for guidance in setting up the CAS system based on the size and length
of the connecting duct work and the input rating of the appliance.
ITEMS INCLUDED:
1- CAS Unit (ETL Listed) "Fan-In-A-Drum"
1- Star Kap (only on SK Models)
2- Mounting Brackets for CAS Unit
2- Wire/Conduit connectors
1- 24VAC Control Relay (SPDT)
1- 120VAC Control Relay (SPDT)
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:
Installation Date:
www.fieldcontrols.com
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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 will typically activate before
the CAS unit.
After the heating requirement has been satisfied, the thermostat circuit will open and deactivate the 2.
burner and CAS unit.
For power vented systems with a post purge device, the power venter will operate for a period of time 3.
determined by the post purge timer setting 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 1.
individual who has been properly trained or a licensed installer.
Plan the system layout before installation to avoid the possibility of accidental contact with concealed 2.
wiring or plumbing inside walls.
Disconnect power supply before making wiring connections to prevent electrical shock and 3.
equipment damage.
SIZING AND SETUP
Diagram A shows the maximum equivalent length and size of duct pipe that should be used when installing
the CAS-6 system; Diagram B shows the same for the CAS-7. Using this table 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 various sizes of duct pipe for the CAS-6 and CAS-7. Follow the
guidelines below to properly size and set up the CAS system.
Determine the input firing rate of the appliance, or the total firing rate of multiple appliances that will 1.
be used.
Determine the location of the CAS unit according to the guidelines in the Installation section.2.
Determine where the intake air StarKap will be located based on the recommendations in the Installation 3.
section.
On Diagram A or B (as appropriate), locate the point that corresponds to the firing rate along the 4.
horizontal axis and draw a vertical line through this point.
The line should pass through at least one of the pipe size regions on the table. The regions correspond to 5.
the maximum equivalent lengths of the given diameter duct pipe that will be adequately sized for
the application.
Calculate the equivalent length of the smaller diameter duct pipe that may be used with the particular 6.
CAS system, including elbows, reducer/increaser and other fittings (except the StarKap, see the Field
Controls Contractor Reference Guide). The effects of the StarKap are already figured into the diagram,
so do not attempt to include any value for the StarKap in your calculation for equivalent length. Draw a
horizontal line through the point corresponding to the equivalent length on the vertical axis.
Locate the intersection of the two drawn lines. If the intersection lies in the region for the equivalent length 7.
of pipe for which the equivalent length was calculated, then that diameter of duct pipe will be of sufficient
size for the application. If not, then repeat step 7 using a larger diameter duct, then proceed to step 9.
If the intersection of the two lines falls into the larger duct region, then that diameter duct will be of 8.
sufficient size for the application. If it falls to the right of the larger pipe region, then even larger pipe or
additional CAS units will be required for the application. For assistance in this case, call Field Controls
Technical Support at 1-800-742-8368.
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0.0
25. 0
50. 0
75. 0
100. 0
125. 0
150. 0
175. 0
200. 0
400 600 800 1000 1200
2.90 3.90 4.90 5. 90 6. 90 7. 90
12"
PIPE
10"
PIPE
6"
PIPE
8"
PIPE
6" DUCT
REGION
8" DUCT
REGION
10"DUC T
REGION
12" DUCT
REGION
OIL INPUT FIRING RA TE, GPH
INPUT FIRING RATE (BTU/H x 1000)
#2 OIL = 140,000 BT U/GA LL ON
EQUIVALENT LENGTH OF PIPE (ft.)
DIAGRA M A
CAS-6 (FAN + STARKAP SK-10) SIZING C HART
MAX. EQUIV ALENT FEET OF PIPE
Example: An oil fired appliance firing at 10.5 gph where a CAS-7 unit needs to be placed at a location
requiring 80' of pipe from the StarKap, using two 90
o
elbows:
From Diagram B, a vertical line is drawn through the point at 10.5 gph on the Oil Firing Rate scale. For 80
feet of 10" pipe, two 90 degree elbows, and two increaser/reducers, the equivalent length is 80 + 18 + 18 +
6 + 6 = 128' of equivalent length. A horizontal line drawn through the point at 128' on the Equivalent Length
scale intersects the vertical line in the 12" duct region of the diagram. Since the intersection is not in the 10"
duct region, recalculate the equivalent length using 12" duct: 80 + 21 + 21 + 7 + 7 = 136' of equivalent
length. A horizontal line drawn through the 136 point on the Equivalent Length scale intersects the vertical line
within the 12" duct region of the diagram; therefore, 12" duct will be of sufficient size for the application.
Diagram A
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DIAGRA M B
CAS-7 (FAN + STARKAP SK-12) SIZING CHART
MAX. EQ UIVALENT FEET OF PIPE
0.0
25.0
50.0
75.0
100.0
125.0
150.0
175.0
200.0
800 1000 1200 1400 16 00 1800 200 0
INPUT FIRING RA TE (BTU/H x 1000)
#2 OIL = 140,000 BT U/GALLON
EQUIVALENT LENGTH OF PIPE (ft.)
5.7 6.7 7.7 8.7 9.7 10.7 11.7 12.7 13.7
OIL INPUT FIRING RA TE, GPH
12"
PIP
E
10 "
PIPE
8"
PIPE
14"
PIPE
8" DUCT
REGION
10" DU CT
REGION
12" DU CT
REGION
14"
DUCT
REGION
Diagram B
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Table 1
®
CAS-6 OIL
(gph)
MAXIMUM EQUIVALENT LENGTH OF PIPE, INCLUDING STARKAP
CAS-6 GAS
(BT U/hr)
8" duct 10" duct 12" duc t
3 420,000 410 1253 311 9
3.25 455,000 344 1051 2616
3.5 490,000 291 890 2217
3.75 525,000 249 760 1893
4 560,000 214 653 1627
4.25 595,000 185 584 1405
4.5 630,000 160 489 1217
4.75 665,000 139 424 1057
5 700,000 121 369 919
5.25 735,000 105 321 800
5.75 805,000 79 241 601
6 840,000 58 176 519
6.50 910,000 49 151 377
CAS-7 OIL
(gph)
CAS-7 GAS
(BT U/hr)
10" duct 12" du ct 14" duct
6 840,000 469 116 7 2523
6.5 910,000 381 948 2050
7 980,000 3 11 776 1678
7. 5 1,050,000 256 637 1378
8.25 1,155,000 191 476 1029
9 1,260,000 142 354 76 6
9.75 1,365,000 104 260 563
10.5 1,470,000 74 186 403
11. 2 5 1,575,000 51 127 2 74
12 1,680,000 31 78 207
12.75 1,785,000 15 39 114
12.88 1,803,000 13 33 72
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INSTALLATION
PLACEMENT OF THE CAS UNIT
The motorized CAS unit should be located on a flat horizontal surface
near the combustion air intake of the appliance. 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 STARKAP LOCATION
The StarKap should be located on an outside wall or roof maintaining
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
StarKap should be located at least 10' from a building exhaust outlet,
equipment vent, or chimney termination.
INSTALLATION OF INTAKE AIR STARKAP
After determining the location of the StarKap, cut an
appropriately sized hole in the wall or roof, taking
precautions to avoid interference with wiring or other
plumbing in the structure to be cut. Pre-attach a short
length of duct to the StarKap if necessary. Insert the
StarKap and secure with appropriate fasteners. Flash in
the opening in accordance with local building codes.
Figure 1
INSTALLATION OF DUCT
Refer to Diagram A or B to determine what size pipe is
needed. Connect the duct pipe from the top of the CAS
unit to the StarKap. If using pipe of different diameter
than the CAS component connections, attach increaser/
Figure 2
reducer fittings as close to the CAS unit and to the
StarKap as possible. 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) For best performance, install elbows or tees no closer
than 3 pipe diameters from the inlet of the CAS unit.
WIRING
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
Figure 3
device rated at 20 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 higher, according to the installation environment.
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Remove the wiring access cover to access the wiring terminals. 1.
Select the appropriate control relay for the appliance control system voltage from the two relays supplied 2.
with the CAS system (see illustration). Use the 24VAC relay for a 24V control system (typical gas-fired),
or the 120VAC relay for a 120V control system (typical oil-fired). Install the selected relay into the socket
provided on the wiring panel, and secure with the wire retaining clip.
Use the enclosed conduit connectors or like connectors to route the appropriate wires through the CAS 3.
housing. The incoming ground wire must be attached to the green grounding screw located 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. Such as when a figure refers to a CK-60 series kit,
a CK-60, 61, 62, etc. may be used. If further information or additional wiring diagrams are needed please
consult Field Controls' technical support.
INTERNAL WIRING CONNECTIONS FOR THE CAS UNIT
Refer to Figure 3 for the internal wiring of the CAS-6/7 unit.
EXTERNAL WIRING CONNECTIONS
Refer to Figure 4 for typical 120 VAC oil fired burner or Figure 5 for 24 VAC gas fired burner connections that
should be used when connecting the CAS unit. Refer to Figure 6 for connecting a single 120 VAC appliance
to the CAS, or Figure 7 for 24 VAC. The three wires BURNER, WHITE, and ORANGE in Figure 4 correspond
to the same wires shown in Figures 6 & 10. The three wires labeled 1, 2, and 3 in Figure 5 correspond to the
same wires shown in Figures 7-9. Refer to Figures 8-10 for connecting multiple appliances to one CAS unit. Note
that an RJR-5 or RJR-6 relay and/or a CAC-24, CAC-120 or DIP-1 are required on certain multiple-appliance
applications. Figure 11 shows how the pressure switch port on the CAC/DIP-1 should be attached to the CAS.
1
Note that the correct
1
suitable for
⁄4" tubing installed as shown in order to connect the CAC pressure port/DIP-1.
⁄4" plastic tubing on the top of the CAS unit must be cut and a 3-way male barb TEE
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Figure 4
Figure 5
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Figure 6
Figure 7
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Figure 8
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Figure 9
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Figure 10
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Figure 11
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Figure 12
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MAINTENANCE
Inspect the system annually to ensure proper operation by observing that the fan activates when a call for 1.
heat occurs and deactivates when the call for heat is satisfied.
Disconnect power to the CAS unit and repeat Step 1.2. NOTE: The unit should not run and the appliance
should not fire in this condition.
Inspect the duct pipe for loose joints, damage, and security to the CAS unit and StarKap.3.
Clear any obstructions, if present, from the inlet of the StarKap and the outlet of the CAS unit.4.
Periodically, the fan blade chamber may need cleaning. First, disconnect the power supply to the CAS. 5.
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.
CAUTION: A minimum clearance of 1" must be maintained between the bottom of the fan blade and the
top of the metal surface underneath. FAILURE TO MAINTAIN THIS CLEARANCE MAY RESULT IN A FIRE
HAZARD AND WILL VOID THE WARRANTY.
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 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.
MODEL ITEM DESCRIPTION PART NUMBER
AC Motor 46363400
Blower Wheel 46363600
Pressure Switch 46363500
CAS-6
Timer Relay 4 614 470 0
24 VAC Control Relay SPDT 46080200
120 VAC Control Relay SPDT 4 61111 0 0
AC Motor 46363400
Blower Wheel 46363700
Pressure Switch 46363500
CAS-7
Timer Relay 4 614 470 0
24 VAC Control Relay SPDT 46080200
120 VAC Control Relay SPDT 4 61111 0 0
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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.
© Field Controls, LLC P/N 46371700 Rev C 11/09
Phone: 252.522.3031 • Fax: 252.522.0214
www.fieldcontrols.com
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