Submittal Sheet

Page 8
COMBUSTION AIR DUCT WORK INSTALLATION
1. A maximum of 30 linear feet of 4” duct pipe and two (2) 90° elbows at maximum firing rate may be used (44 equivalent
feet). Subtract 7 feet from the maximum linear feet for every additional 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 3)
Table 3
Pipe
Diameter
Maximum Equivalent
Pipe Feet (between Air boot™
and duct termination)
Elbow*
Equivalent
Feet
Reducer or
Increaser
Equivalent Feet
4” 44’ 7’ -
5” 60’ 9’ (4” to 5”) 3’
6” 90’ 11’ (4” to 6”) 6’
*Note: Subtract the elbow or reducer equivalent feet from the maximum
equivalent feet to get maximum linear feet of pipe.
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.
INSTALLATION USING SINGLE WALL VENT PIPE
(SEE TABLE 4)
Table 4
CV-4VR & 5VR INSTALLATION CLEARANCES TO COMBUSTIBLES
Vent Pipe Clearances
Max. Inlet Temperature Through-wall Clearance
Double Pipe
System
Single Pipe
System
400°F or Less ½” min ½” min 3” min
1” min 4” min
400°F-650°F (US)
400°F-575°F (Can)
½” min
½” min with
sheet metal liner
3” min with sheet
metal liner
*CAUTION: Air Tee Cover Plate must be in position on Air Tee when not providing combustion air.
NOTE: Vent pipe joints should be secured with at least (3) three sheet metal screws.
Table 5
Model Hole Dimensions
CV-4VR Min. 7-1/8” Square
CV-5VR Min. 8-1/8” Square