25
DES3
Series
General Venting Requirements
The venting system for DES3 Series heaters may terminate horizontally through a sidewall or vertically
through the roof, and may be individually or commonly vented. Configuration of the vent termination
determines the category type. All model heaters must be installed in accordance to the requirements of
this section, as well as the requirements of its category determination, as described in this manual. To
determine your applications category type, review ‘Vertical Venting’ (Category I) and ‘Horizontal Venting’
(Category III) sections of this manual.
All DES3 Series Model Requirements:
• Exhaust vent pipe must be 4 inch nominal size.
• Use vent pipe material that is corrosion-resistant galvanized steel of a thickness that meets the
National Fuel Gas Code.
• Do not exceed a maximum vent length of 20 feet.
• Maintain a minimum vent length of 3 feet.
• Maintain a minimum 12 inches of straight pipe from the flue outlet before any directional changes
are made in the venting system.
• Have all vent pipe seams or connectors fastened together with at least three corrosion resistant
sheet metal screws (field supplied).
• Maintain a 6 inch clearance around all single wall vent pipe from any combustible materials. For
double wall vent pipe (type B) follow the vent manufacturer’s clearance to combustibles.
• The equivalent length for a 4 inch 90° elbow is 5 feet.
• Avoid using more than two 90° directional changes in the venting system.
• Horizontal sections of the vent pipe must be installed with an upward slope from the appliance at a
pitch of ¼ inch per foot.
• Suspend and secure all horizontal runs at points no greater than 3 feet apart.
• Vent termination must maintain a minimum distance of 6 feet from any mechanical air supply inlet.
• Vent must terminate a minimum of 4 feet below, 4 feet horizontally from, or 1 foot above any window
or door that may be opened or gravity air inlet into the building.
• Vent must terminate a minimum of 4 feet above grade level and must extend beyond any
combustible overhang. Vents adjacent to the public walkways must terminate a minimum of 7 feet
above grade level.
• The vent terminal must be installed to prevent any blockage by snow and protect building material
from degradation by flue gases.
• The vent cap must be a minimum of 6 inches from the sidewall of the building.
• Vent must be a minimum of 36 inches below or extend beyond any combustible overhang.
• Consult NFPA ANSI Z223.1 Gas Vent Termination criteria for vents that terminate on a roof pitch that
exceeds 9:12.
•
Canada:
Vents must terminate a minimum of 3 feet from a window or door that may be opened, and
a non-mechanical air supply inlet or combustion air inlet into the building.
3.0
Installation
•
General Venting Requirements