Vent / Combustion Air Installation
11
Category IV Vent Guidelines
1. Vent system installation must be in accordance with Local
codes or, in the absence of local codes, the National Fuel
Gas Code, ANSI Z223.1 / NFPA 54 and/or CSA B149.1,
Natural Gas and Propane Installation Code.
2. Do not install venting system components on the
exterior of building except as specifically required by
these instructions
-
Vent terminals must be at least 4 feet from any
door, window, or gravity inlet into the building.
-
The bottom of the vent terminal must be at least
12˝ above the normal snow line. In no case
should it be less than 12˝ above grade level.
-
Do not install the vent terminal directly over win-
dows or doors.
-
For sidewall venting, the minimum horizontal
distance between any adjacent water heater
vent terminations is twelve (12) inches. It is bet-
ter to be far more than 12 inches for avoiding
frost damage to building surfaces where vent
terminations are placed.
The Category IV vent termination must also maintain the
following clearances; as shown below.
a. At least 3 feet [0.9 m] from adjacent walls
b. At least 3 feet [0.9 m] below roof over hangs
c.
At least 7 feet [2.1 m] above any public walkways
d. At least 3 feet [0.9 m] above any forced air intake
within 10 feet [3 m].
e. No closer than 4 feet [1.2 m] below or horizon-
tally from any door or window or gravity air inlet.
Maximum Allowable Vent Lengths (PVC, CPVC, PP)
Note:
Reduce maximum allowable length:
•
5 feet (1.5 M) for each additional 3-inch 90
degree elbow
•
2.5 feet (0.75 M) for each additional 3-inch 45
degree elbow
•
8 feet (2.4 M) for each additional 2-inch 90
degree elbow
•
4 feet (1.2 M) for each additional 2-inch 45
degree elbow
•
The thickness of the wall vents installed:
Min 4” ~ Max 20”
Vent Termination
1. Bird Screen Installation
•
Install Bird Screen at Vent Terminal
•
After connecting vent/air inlet terminal, it is
required to install screen for the terminal to pre-
vent blockage, which might cause damage to
the unit.
Termination Clearances
of Category IV System
TWH
18
0/
TWH
18
0LP
Maximum
Length
Maximum
Elbows
2” Combustion Air /
Vent Pipe
50’ (15 M)
4
3” Combustion Air /
Vent Pipe
100’ (30 M)
6
Marquis Manual_61515_Water Heater 7/1/15 1:58 PM Page 14
Summary of Contents for Marquis TWH180
Page 26: ...23 Control System Marquis Manual_61515_Water Heater 7 1 15 1 58 PM Page 26 ...
Page 27: ...24 Control System Ladder Diagram Marquis Manual_61515_Water Heater 7 1 15 1 58 PM Page 27 ...
Page 34: ...31 Repair Parts Diagram Marquis Manual_61515_Water Heater 7 1 15 1 58 PM Page 34 ...
Page 36: ...33 Repair Parts Diagram Marquis Manual_61515_Water Heater 7 1 15 1 58 PM Page 36 ...
Page 37: ...34 Repair Parts Diagram 4 Marquis Manual_61515_Water Heater 7 1 15 1 58 PM Page 37 ...
