Direct Vent Combustion Air Intake; Maximum Intake Piping Length - IBC DC Series Installation And Operating Instructions Manual

INSTALLATION
DC SERIES BOILERS / WATER HEATERS DC 15-95, DC 15-96, DC 20-125, DC 33-160
Figure 15: Direct vent combustion air intake
For 3" Flexible PPs, up to 35 actual lineal feet are allowed in a nominally vertical
orientation (>45°). The equivalent length of 3" Flexible PPs shall be computed
using a multiple of 1.4:1, e.g. 35' x 1.4 = 49' equivalent. The balance of the
venting allowance is still available for use with rigid PPs piping material. 2"
Flexible PPs is not allowed.
INTAKE PIPE SIZE/FITTINGS
Schedule 40 ABS PVC, CPVC or PPs – Allowances are for each side separately.
2"
3"
2" or 3" 90' Long Sweep Vent Elbow
2" or 3" 90' Short Sweep Vent Elbow
2" or 3" 45' Vent Elbow
PPS
PPs 87-90' Elbow
Flex PPS
3" PPs Flex
Table 4: Maximum intake piping length.
For the inlet air – Schedule 40 PVC, CPVC, ABS or PPs piping of any type is
permitted. Use same diameter as Vent pipe.
Combustion air piping is inserted directly into the 3" female stainless steel fitting
on the top, right side of the boiler / water heater and run horizontally or vertically
to the outdoors. Bird screen of 1/4" stainless steel or plastic mesh (eg. IPEX
System 636 drain grate for CPVC systems) is useful to guard against foreign
objects.
Care must be taken to ensure adequate separation is maintained between the
air intake inlet and the vent terminal. Refer to the vent terminal configuration
drawings in the Vent Termination section above.
MAXIMUM EQUIVALENT LENGTH
35'
120'
Allow 5 equivalent feet
Allow 8 equivalent feet
Allow 3 equivalent feet
Allow 8 equivalent feet
(Max. 35) actual feet times 1.4
1-15