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UBXC-UDXC-IOM (01-24) 1042980-0
INSTALLATION—CONTINUED
Vent Connections for Standard Units—Continued
Category I Commercial/Industrial or Residential (Model UDXC) Installations with Vertical Dedicated Vent
Commercial/Industrial installations of either model or residential installations of model UDXC unit sizes 30–100 may
use a Category I vertical dedicated vent. To permit this, at least 75% of the equivalent length of the vent run must be
vertical and the vent must terminate at least 5 feet above the vent outlet of the heater. All vertically vented heaters
that are Category I must be connected to a chimney or vent complying with a recognized standard or a lined masonry
(or concrete) chimney with a material acceptable to the authority having jurisdiction. Venting into an unlined masonry
chimney is not permitted. Install the vent as follows:
1. Select type of pipe for standard vertical (Category I) vent. Double-wall vent pipe is recommended. Use single-wall
vent pipe if requirements of the National Fuel Gas Code are followed.
2. Determine vent pipe diameter and length for vertical vent. Unit sizes 30–75 require 4-inch vent. Unit size 100
requires 4- to 5-inch adapter and 5-inch pipe.
3. Determine venter (flue) outlet diameter (refer to Venter (Flue) Outlet Diameter section).
4. Make all vent pipe joint connections in accordance with Vent System Sealing section.
5. Properly support all vent pipe runs in accordance with Vent System Support Requirements section.
6. Take appropriate steps to mitigate condensation in accordance with Condensation Mitigation section.
7. Terminate vent as follows:
a. Install UL listed Category I terminal vent pipe and terminate vent with option CC1 or CC21 vent cap or Novavent
#2NVTB4 vent cap.
b. Refer to instructions shown in Figure 12 to install vertical vent terminal.
c. Ensure that vent terminal is installed in accordance with Vent Terminal Requirements section.
Category I Residential Installations with Common Vent (Model UDXC)
⚠ DANGER ⚠
The installer must comply with the venting requirements listed in this section, with the instructions
provided for other appliances that are to be commonly vented with the unit, and with applicable local
codes. Verify that any appliances being commonly vented with the unit are designed for Category
I common venting. Failure to comply may result in severe injury, death, and/or property damage.
Residential installations of model UDXC unit sizes 30–100 may use a Category I common vent. Common venting is
when two or more Category I appliances are vented into a single vertical vent. Install the vent as follows:
1. Select vent pipe and vent connector for Category I vent (see Figure 15).
2. Determine vertical height of vent based on vent capacity in accordance with Table 15.
NOTE: Table 15 applies to Type B double-wall common vents including lined masonry chimneys.
If a conflict in capacity occurs with other instructions, the more conservative capacity must be
chosen.
3. Determine maximum length of horizontal connector pipe in accordance with Table 16.
NOTE: When two or more vent connectors enter a common vent, the smaller connector shall enter
at the highest level consistent with available headroom or clearances to combustible material.
4. Determine venter (flue) outlet diameter (refer to Venter (Flue) Outlet Diameter section).
5. Make all vent pipe joint connections in accordance with Vent System Sealing section.
6. Properly support all vent pipe runs in accordance with Vent System Support Requirements section.
7. Take appropriate steps to mitigate condensation in accordance with Condensation Mitigation section.
8. Terminate vent with option CC1 vent cap. Ensure that vent terminal is installed in accordance with Vent Terminal
Requirements section.
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