Field Controls 46284600 User manual

2630 Airport Road · Kinston, NC 28504
Phone: [phone]· Fax: [phone]
www.fieldcontrols.com
2630 Airport Road · Kinston, NC 28504
Phone: [phone]· Fax: [phone]
www.fieldcontrols.com
COMBUSTION AIR SYSTEM
Model: CAS-4
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
millivolt powered system 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. If an
optional Vacuum Relief Valve (VRV) is used, the incoming air is tempered
before entering the structure's airspace. Refer to Diagram A and 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.
This device MUST be installed by a qualified agency in accordance with the manufacturers 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 gas appliances, who is experienced
in such work, familiar with all the precautions required, and has complied with the requirements of the authority having
jurisdiction.
DO NOT DESTROY
THESE INSTRUCTIONS MUST REMAIN WITH EQUIPMENT
ITEMS INCLUDED IN KIT:
1) Motorized Blower
1) 4" galvanized intake air Vent Hood
2) Mounting brackets to secure the CAS to a wall
2) Wire/conduit connector(s)
1) 4" x 6" Pipe Increaser Fitting
1) 6" Orifice Ring
1) Instruction Sheet
1) High/Low Motor Speed Switch

Page 2
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 maximum input firing rate of the appliance, or the maximum 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. When calculating the
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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8. Draw a horizontal line on Diagram A or B that passes through the point located in step 5. The
position of the point along this line relative to the left and right borders of the region it falls into
indicates the relative position that the balance weight of the VRV should be adjusted to. If the
point falls near the leftward border of a region, then the VRV balance weight should be adjusted to
it's minimum position. This corresponds to turning the balance weight screw as far counter-
clockwise as possible.
EXAMPLE: 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.
From Diagram A or B, the point at 100,000 BTU/Hr on the "Gas Firing Rate" scale
and 30 equivalent feet falls in the "4 inch Duct, Hood, and Orifice Ring" region.
The point is approximately 2/3 of the horizontal distance between the left and right
boundary of the region. The left boundary is the edge of the graph, the right
boundary is the diagonal line that says "4 inch Duct, Hood & Orifice Ring."
Therefore, place the Orifice Ring into the inlet of the CAS so that it sits on the
ledge above the fan. It does not matter which way the Orifice Ring is turned as
long as it is pushed down against the ledge completely. Use 4" diameter pipe to
connect the vent hood and the CAS unit. Install a VRV and the included 4x6 inch
Increaser on top of the CAS unit and adjust the balance weight to 2/3 of the
distance of it’s full adjustment range from it’s minimum setting. The minimum
setting is with the balance weight turned all of the way counterclockwise.
Total Input of
Appliance Maximum Equivalent Feet of Installation
4” Duct And Hood
W/Restrictor 4” Duct And 4” Intake Air Hood 6” Duct And 6” Intake Air Hood
CAS-4,4mV
Gas
(BTU/hr) HI LOW HI LOW HI LOW
50,000 300 300 300 300 300 300
75,000 300 300 300 300 300 300
100,000 300 300 300 300 300 300
125,000 300 220 300 220 300 300
150,000 174 108 232 118 300 300
175,000 99 48 152 63 300 300
200,000 52 14 102 32 300 300
225,000 20 NA 68 13 300 239
250,000 NA NA 45 NA 300 150
300,000 NA NA 16 NA 300 53
350,000 NA NA NA NA 193 8
400,000 NA NA NA NA 109 NA
450,000 NA NA NA NA 56 NA
Table 1

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HIGH SPEED SIZING CHART
0
50
100
150
200
250
300
0 50 100 150 200 250 300 350 400 450 500 550
GAS INPUT FIRING RATE (1000 BTU/hr.)
MAX. EQUIVALENT DUCT LENGTH (ft.)
0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50
OIL INPUT FIRING RATE (gallons per hour)
(1 gallon oil/hr = 140,000 BTU/hr)
6" Duct & Hood
4" Duct & Hood
4" Duct, Hood, & Orifice
Diagram
A
LOW SPEED SIZING CHART
0
50
100
150
200
250
300
0 50 100 150 200 250 300 350 400
GAS INPUT FIRING RATE (1000 BTU/hr.)
MAX. EQUIVALENT DUCT LENGTH (ft.)
0.00 0.50 1.00 1.50 2.00 2.50
OIL INPUT FIRING RATE (gallons per hour)
(1 gallon oil/hr = 140,000 BTU/hr.)
6" Duct & Hood
4" Duct & Hood
4" Duct & Hood w/ Orifice
Diagram B

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INSTALLATION
PLACEMENT OF THE CAS UNIT
The motorized CAS unit should be located on a flat horizontal
surface within the same space as that3 feet of the appliance and
within 3 feet of the combustion air intake as possible. 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 3. 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. The optional Vacuum Relief Valve (VRV) should be
placed directly on the air inlet of the CAS unit if using 6”. (See
Figure 1) Refer to Diagram A to determine if the VRV is needed.
The VRV should be oriented so that the axis of the swinging gate is
horizontal.
ASSEMBLING THE WEIGHTS ON THE VRV
Refer to Figure 2 to assemble the weight assembly, hex nut, and
knurled nut to the VRV gate. After the weight is correctly
positioned, tighten the hex nut against the gate to prevent the
weight assembly from moving during operation.
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 feet from a
power vented exhaust outlet and should be on the same wall. The
intake air hood should be a minimum of 1 foot above grade or
snowlines where applicable.
INSTALLATION OF INTAKE AIR HOOD
After determining the location of the vent hood, cut a 4-1/2 inch
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 or B to determine what size pipe is needed.
Connect the duct pipe from the top of the CAS unit to the Vent
Hood in the wall. If using 4" diameter pipe attach the provided 4" x
6" Pipe lncreaser Fitting to the top of the CAS unit (or the VRV, if
installed). 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 1) A minimum of 12 feet of pipe should be run to help
temper outside air being drawn in. The VRV may also be installed
near the intake air hood and adjusted to mix room air with outside
air to help temper air in cold climates.
Figure 2
Figure 3
Figure 1

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WIRING INSTRUCTIONS
Wire the CAS unit in accordance with the National Electric 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 enclosed 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.
INTERNAL WIRING CONNECTIONS FOR THE CAS UNIT
Refer to Figure 4 for the internal wiring of the CAS-4 unit.
EXTERNAL WIRING CONNECTIONS
Refer to Figures 5-12 for appropriate wiring method. Figure 4
Wire Key WIRE COLOR
MOTOR MANUFACTURER W1 W2 W3
McLean Engineering Black Blue Brown
All Others Brown Black Blue
Figure 5 – Chimney Vent Single 24V Furnace

Page 7
Figure 6 – Power Vent Single 24V Furnace
Figure 7 – Chimney Vent 24V Furnace and 30mV
Water Heater with CK-20FV or CK-20FG

Page 8
Figure 8 – Chimney Vent 24V Boile
r
Figure 9 – Power Vent Single 24V Boile
r

Page 9
Figure 10 – Chimney Vent Two 24V Gas Appliances With CAC-24

Page 10
Figure 11 – One Power Venter Two 24V Gas Appliances With DIP-1

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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, VRV (if installed), 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 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 the Field Controls Technical Support at 1-800-742-8368.
Item Description Field Part Number
Motorized Fan 46274100
Air Pressure Switch 46273100
24 VAC Relay for CAS-4 46161400
Figure 12 - Figure 12 shows how the DIP-1 should be attached to the CAS.
Note that the 1/4" O.D. plastic tubing on the top of the CAS unit must be cut
and a 3-way male barb TEE suitable for 3/16" I.D. tubing placed as shown in
order to connect the DIP-1.

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PN 46284600 Rev G 10
/
06