Prestige Venting Supplement

25
CHAPTER 3
CHAPTER 3 - CATEGORY IV (INDOOR AIR) INSTALLATION OF VENT/AIR PIPING
A Category IV appliance utilizes uncontaminated indoor
or outdoor air (surrounding the appliance) for combus-
tion.
3.1. Category IV - Vertical - Through the Roof
or Unused Chimney
• The installation must conform to the re-
quirements of the authority having juris-
diction or, in the absence of such require-
ments, to the National Fuel Gas Code,
ANSI Z223.1/ NFPA 54, and/or Natural Gas
and Propane Installation Code, CAN/CSA
B149.1.
• When using an inoperative chimney as a
means of a chase for the vent, the surround-
ing space within the chimney cannot be used
to draw combustion air or vent another appli-
ance.
A gas vent extending through a roof must not
terminate near an adjacent wall or below any
building extensions such as roof eaves, bal-
conies or decks. Failure to comply with the re-
quired clearances in this manual can result in
substantial property damage, serious injury, or
death.
The information and diagrams outlining the
fittings and method of terminating the vent/
combustion air are directly related to PVC/
CPVC vent systems. When utilizing an AL 29-
4C
®
or Polypropylene vent system, there may
be some variations. Consult the appropriate
vent manufacturer for recommendations and
clarifications.
NOTICE
WARNING
NOTICE
3.1.1 Determine Termination Location
Locate the vent and combustion air termination using
the following guidelines:
1. The total length of the vent piping must not exceed
the limits given in Table 8 on page 9.
2. The combustion air piping must terminate at the
boiler with a 90º elbow.
3. The vent piping must terminate vertically with a
coupling to accept the bird screen and must be
located 12” [30.5 cm] (18” [45.7 cm] Canada) above
the highest anticipated snow level as shown in Fig.
14 on page 25
4. The following should be considered when deter-
mining the location of the vent termination:
a. Locate the vent termination where ue vapors
will not damage surrounding shrubs, plants, air
conditioning equipment or be objectionable
to the homeowner.
b. The ue products will form a noticeable plume
of water vapor as they condense in colder air.
Avoid terminating the vent in areas where the
plume could obstruct window views.
c. Prevailing winds could cause freezing of ue
gas condensation and a buildup of water / ice
on surrounding plants or building surfaces.
d. Avoid locations where prevailing winds could
aect the performance of the boiler or cause
recirculation of the ue gases, such as inside
corners of buildings, near adjacent buildings,
vertical surfaces, window wells, stairwells, al-
coves, courtyards, or other recessed areas.
Vent Termination
12" [30.5 cm]
(18” [45.7 cm] Canada)
Above the Highest
Anticipated Snow Level
Fig. 14 - Category - IV - Vertical Termination of Vent Pipe