26
CL3
Series
3.0
Installation
•
Vertical Venting (Category I)
Vertical Venting (Category I)
An appliance that operates with a non-positive vent static pressure and with a vent gas temperature
that avoids excessive condensate production in the vent is said to be ‘Category I’. The CL3 series
heater is considered a Category I appliance if the venting system meets all of the following criteria:
• The vent system terminates vertically (up).
• The length of the horizontal portion of the vent run is less than 75% of the vertical rise length.
(e.g.- If the vertical vent height is 10 feet, the horizontal run is less than 7 1/2 feet).
• The vent terminates a minimum of 5 feet above the vent connection on the unit.
• Horizontal venting sections of the vent pipe must be installed with an upward slope from the
appliance at a pitch of 1/4 inch per foot.
For vertical vent termination, the venting must comply with all parts of this section, in addition to the
requirements of the general venting.
Category I (Vertical) venting is venting at a non-positive pressure. An appliance vented as a
Category I is considered a fan-assisted appliance and the vent system does not have to be ‘gas
tight’. It is recommended that the venting system is installed with a tee, drip leg, and clean-out cap
as shown in Figure 3.19.
Vent Locations and Clearances:
• Separate air intake duct from vent pipe by a minimum of 4 feet by placing vent pipes higher than
adjacent air intake ducts.
• Utilize a listed type B vent termination cap.
• The vent terminal must extend a minimum of 2 feet above the roof.
• Vent caps should be located a minimum of 2 feet away from adjoining structures.
All vertically vented heaters that are Category I must be connected to a chimney or vent complying
with a recognized standard, or lined masonry (or concrete) chimney with a material acceptable to
the authority having jurisdiction. Venting into an unlined masonry chimney is not permitted. Refer to
the National Fuel Gas Code and page 25 of this manual.
Use a listed vent terminal to reduce down drafts and moisture in the vent.
When possible, avoid venting through an unconditioned space. Venting through an unconditioned
space promotes condensation. When venting through an unconditioned space is unavoidable, or if the
unit is installed in an area that is prone to condensation, insulate venting runs greater than 5 feet to
minimize the production of condensation. Inspect for leakage prior to insulating the venting and only
use insulation that is non-combustible with a temperature rating of not less than 550°F. Install a tee
fitting at the low point of the vent system and provide a drip leg with a clean out cap as shown in Figure
3.19.
When venting pipe passes through a combustible interior wall or floor, a metal thimble with a diameter
4 inches greater than the vent pipe diameter must be used. If there is 6 feet or more of vent pipe prior
to passing through the combustible wall or floor, then the metal thimble need only be 2 inches greater
than the vent pipe diameter. If a metal thimble is not used, all clearances to combustibles from the vent
pipe must be 6 inches. When permitted, type B vent or Duravent PVP venting may be used for the last
section of vent pipe to reduce the required clearances to combustibles when passing through a
combustible wall or floor. When using type B vent or Duravent PVP venting, follow the manufacturer’s
recommended clearances to combustibles. Any material used to close or insulate the opening must be
non-combustible.
