9
Figure: Terminals of Direct Venting Systems
(taken from NFPA-54 National Fuel Gas Code).
XI. FLUE SYSTEM
CHIMNEY VENT MODELS
A.
Draft
In order to ensure positive pressure over the fire (see specification sheet) and superior boiler perfor-
mance, the draft in the flue pipe should be set to -0.02. In the event that the pressure is not at the set point,
a draft regulator or draft booster may be used to correct for condition. Any draft control used in the vent-
ing system must be of listed type and installed according to local building codes and NFPA-54.
B.
Venting System
1. Use only an approved venting system.
2. Flue or vent connector must be the same size or larger than the outlet at the unit, and must be
inserted into but not beyond the inside wall of the chimney flue.
3. The horizontal length of a chimney connector should not exceed 10 ft. unless a draft booster is
used. The connector should be pitched at least 1/4” to the foot toward the unit.
C.
Roof Clearances
The chimney flue should extend at least 3 ft. above the highest point at which the chimney comes in
contact with the roof, and no less than 2 ft. above the highest roof surface or structure within 10 ft. hori-
zontally of the chimney.
DIRECT VENT MODELS
Install the TV-175 Combination Vent Hood by cutting a 7-1/16" by 7-1/16" opening through an exteri-
or wall. Ensure that the location of the hood is 12" above ground and 3' from any opening. The location
must also be in area with sufficient air flow (alcoves and other obstructions such as shrubbery tend to
starve the burner for air). Please see following schematic.
Flash off the opening for the TV-175 Combination Vent Hood. Place additional insulation between the
sides of the hood and the exterior wall to seal the opening.
Connect the air intake and flue from the boiler to the combination vent system (kits are available in 10',
15' and 20' lengths). The 4" duct is for the air intake and the 5" AL 29-4C is for the exhaust. Connect the
joints for the exhaust venting by using a silicon Sealant and tightening the attached cable clamps.
