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D
W
I
UCT
ORK
NSTALLATION
1. Duct length distance, a maximum of 30 linear feet of standard duct pipe and two (2) 90° elbows at
maximum firing rate. Subtract 7 feet from the maximum linear feet for every 90° elbow added.
Longer pipe lengths require the use of a larger pipe between the VRV and the intake
hood. It also requires the use of a vent pipe increaser at the VRV and a reducer at the
intake hood. (See Table 1)
Table 1
Pipe
Diameter
4"
5"
6"
2. Route the duct work from the VRV tee to the inlet vent termination with as minimum a number of
elbows as possible.
3. Secure and support the duct work for the design and weight of the material used, to prevent physical
damage and separation of joints. For guidelines refer to recognized national building codes or
according to any local codes.
4. To reduce uncontrolled air leakage into the duct, tape all joints and seams using standard duct tape.
NOTE: Try to run a minimum of 12 feet of duct to help temper the outside air being brought into
burner.
A
A
IR
DJUSTMENT
1. Adjust the air adjustment knob on the side of the Air Boot™ (See Table 2) to rough air setting.
NOTE: For proper burner operation, burner should be set up by using a combustion analysis
test set.
2. Start the burner and adjust the air control as needed to achieve the required CO
fire draft to appliance manufacturers' specifications (typically -.02" of water). Secure air control knob with
indicator bracket. If draft levels are not obtainable or controllable, use standard industry methods to control the
draft or call the Field Controls Tech Line at 1-800-742-8368 for more information, or check the website at
www.fieldcontrols.com.
3. Next, adjust the VRV gate by screwing the adjustment weight in until the VRV gate is just closed.
4. Re-check the burners operation and adjust accordingly.
5. Lock the adjustment weight in position by tightening the hex nut on the VRV gate.
Maximum Equivalent
Pipe Feet (between Air boot™
and duct termination)
*Note: Subtract the elbow or reducer equivalent feet from the maximum
equivalent feet to get maximum linear feet of pipe.
Table 2
GPH
CAS-2B
.75
25°
1.00
60°
1.50
160°
44'
60'
90'
ROUGH AIR SETTING
Knob Setting
CAS-2C
15°
25°
105°
Page 5
Elbow*
Reducer or
Equivalent
Increaser
Feet
Equivalent Feet
7'
9'
(4" to 5") 3'
11'
(4" to 6") 6'
CAS-2W
70°
90°
135°
and smoke levels. Set over
2
-
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