Prestige Venting Supplement

35
CHAPTER 5
Combined Maximum
Input (MBH)
Minimum Diameter of Com-
bustion Air Piping
<400 4”
400-600 5”
601-800 6”
801-1600 8”
1601 -2000 10”
Table 9 - Common Combustion Air Piping
5.1. Manifold Combustion Air Option for
Multiple Prestige Boilers
1. Common combustion air manifold is restricted to
horizontal/side wall terminations only.
2. The number of Prestige boilers connected to a com-
mon combustion air manifold system is limited by
the combined maximum boiler input shown in Table
9.
3. The combustion air manifold must be constructed
of round solid core PVC pipe with minimum diame-
ter based on combined maximum boiler input. See
Table 9 below.
5.3. Sidewall Termination
• The common combustion air manifold must termi-
nate horizontally on a side wall using a 90° elbow
pointed downward.
• The inlet elbow of the common combustion air
termination must include a corrosion resistant eld
supplied bird screen.
• The edge of the common combustion air termina-
tion coupling must extend 1” (2.5 cm) beyond the
exterior wall as shown in Fig. 6 on page 19.
• The inlet of the common combustion air termina-
tion must be located 12” (30.5 cm) minimum above
grade/highest anticipated snow level.
• The common combustion air termination must be
a minimum of 3 feet (0.9 m) below any appliance
vent termination within 10 feet (3 m) horizontally.
• The common combustion air termination must be
a minimum of 3 feet (0.9 m) horizontally from any
appliance vent termination.
• Avoid locating the common combustion air termi-
nation in a location where prevailing winds could
aect the performance of the boilers or cause re-
circulation of ue gases, such as inside corners of
buildings, near adjacent buildings, vertical surfac-
es, window wells, stairwells, alcoves, courtyards, or
other recessed areas. The common combustion air
termination must be installed a minimum of 6 feet
horizontally from any such locations.
• Locate the common combustion air termination in
a manner to protect from damage by foreign ob-
jects, such as stones, balls, or buildup of leaves or
sediment.
CHAPTER 5 - MANIFOLD COMBUSTION AIR
5.2. Combustion Air Manifold Equivalent
Length
1. The maximum equivalent length of the combus-
tion air manifold must not exceed the lowest maxi-
mum allowable length for the boilers connected to
the manifold per Table 8 on page 9.
2. Reduce the maximum equivalent length of the
combustion air manifold as follows:
• 5 Feet for every 45º elbow
• 10 feet for every 90º elbow