Detroit Radiant Products Company UH Series - Manual (Page 29)

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UH Series 3.0 Installation • Vertical Venting (Category I) • Vent Locations and Clearances
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 UH 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.
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. A furnace 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 3.9.
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 27 of this manual.
Use a listed vent terminal to reduce down drafts and moisture in the vent.