Reznor Unit Heater Venting Instructions

General Information

This manual provides venting instructions and must be used in conjunction with the installation manual shipped with the heater. Contact your distributor if either manual is missing.

Important Safety Information

Read all information thoroughly before operating or maintaining the unit. Pay attention to all danger, warning, caution, and note statements. Safety markings are crucial.

• DANGER: Potentially hazardous situation that may result in severe personal injury, death, and/or property damage if not avoided.
• WARNING: Potentially hazardous situation that may result in severe personal injury and/or property damage if not avoided.
• CAUTION: Potentially hazardous situation that may result in minor or moderate personal injury and/or property damage if not avoided.
• NOTE: Important information that should not be ignored.

CAUTION: Do not use these units in applications where the heated space temperature is below 50°F (10°C), as this may cause condensate to form in the heat exchanger.

DANGER: Each heater requires its own individual vent pipe run and vent cap. Manifolding vent runs can cause recirculation of combustion products, leading to severe personal injury, death, and/or property damage. Heaters certified for residential use are intended for heating non-living spaces attached to or part of a structure containing family living quarters, not as the primary heat source or for sleeping quarters. Installation must be performed by a qualified agency.

Venting Requirements

These unit heaters are certified as Category III heaters and are designed for safe and efficient operation with either horizontal or vertical venting. Comply with specific requirements.

Unit sizes 030, 045, 060, 075, 100, and 125 of Model UDX are certified for commercial/industrial and residential installation. Requirements vary based on installation type. Follow instructions applicable to your installation.

Venting must comply with local codes and the National Fuel Gas Code Z223.1 or CAN/CSA B149.1 and B149.2. Local requirements supersede national ones.

CAUTION: When replacing an appliance in a venting system, verify the system is properly sized for the new appliance. Improper sizing can lead to condensate, leakage, or spillage. Do not intermix vent system parts from different manufacturers. Do not vent into an existing gravity vent or chimney.

Venter (Flue) Outlet Diameter

Attach vent pipe directly to the collar or use a taper-type connector. For category I vent pipe, use a 4-inch appliance adapter and a reducer if using 3-inch pipe. For category III vent pipe, use a 4-inch appliance adapter and a reducer if using 3-inch pipe. Refer to Table 1 for venter (flue) outlet diameters.

Vent System Sealing

Joint sealing depends on pipe type:

• Category III pipe: Follow manufacturer's instructions for secure, sealed joints.
• Single-wall galvanized pipe (26-gauge or heavier): Secure slip-fit connections with sheet metal screws or rivets. Seal joints and seams inside the building using aluminum tape or silicone sealant.
• Double-wall type B vent pipe: Join sections per manufacturer's requirements. Refer to Appendix A for connection details.

Table 1. Venter (Flue) Outlet Diameter

Vent System Support Requirements

• Support horizontal runs every six feet (1.8 meters).
• Support vertical runs (type B double-wall, category I, or category III) per pipe manufacturer's requirements.
• Support vertical single-wall pipe per accepted industry practice.

CAUTION: Do not rely on the heater to support vent pipe. Use non-combustible supports.

Condensation Mitigation

For units with long vent runs (over 50% of maximum length) or in low ambient conditions (below 50°F), fit vent pipes at the low point with a tee, drip leg, and cleanout cap to prevent moisture from entering the unit. Inspect and clean the drip leg periodically.

Any length of single-wall vent pipe exposed to cold air or run through an unheated area (50°F or less) must be insulated with a minimum of 1/2-inch foil-faced fiberglass, 1-1/2# density insulation.

Horizontal vent runs must be pitched down toward the terminal end at 1/4-inch per foot for condensate drainage.

CAUTION: Failure to pitch the vent run properly can damage the heater due to condensate. Exceeding vent pipe diameter and length requirements may lead to condensate formation.

Vent Terminal (Type of Pipe and Vent Cap) Requirements

DANGER: To prevent combustion products from entering the occupied space, all vent terminations must be positioned away from fresh air intakes, doors, and windows. Failure to comply can result in severe personal injury, death, and/or property damage. Consider local snow depth; the vent must be at least 6 inches (152 mm) above anticipated snow depth.

WARNING: Using a different style vent cap may cause problems or unsafe conditions. The vent cap must match the vent pipe size. Do not locate a vent termination where it may cause hazardous frost or ice accumulations on adjacent property. Maintain required clearance from the wall to the vent terminal cap for stability and building protection.

Refer to Table 2 for horizontal vent terminals.

NOTE: Products of combustion can discolor building finishes and deteriorate masonry. Applying a clear silicone sealant can protect masonry. If discoloration is an issue, relocate the vent or install a vertical vent.

Table 2. Minimum Clearance Requirements for Horizontal Vent Terminal

*Does not apply to the inlet of a direct vent appliance.
**Do not terminate the vent directly above a gas meter or service regulator.

Vertical vents must terminate with minimum horizontal and vertical distance from roof lines and adjacent walls or obstructions, as outlined by National Fuel Gas Code for vents with diameters less than 12 inches.

• For double-wall vent pipe and a horizontal distance to any vertical wall or obstruction of 8 feet or greater, terminate above the roof per Figure 1 and Table 3.
• For double-wall vent pipe and a horizontal distance to any vertical wall or obstruction of less than 8 feet, terminate at least 2 feet above the highest point of roof penetration and at least 2 feet higher than any portion of a building within a 10-foot horizontal distance (refer to Table 3).

Figure 1. Roof Slope and Pitch

Table 3. Vent Termination Height

*See Figure 1. Termination locations for gas vents with listed caps 12 inches (300 mm) or less in size at least 8 inches (2.4 meters) from a vertical wall.

Installation

Installation instructions vary for commercial/industrial and residential applications. Refer to the specific sections for each.

Instructions for Commercial/Industrial Installations (Model UBX or UDX, All Unit Sizes)

Commercial/industrial installations may use a horizontal or vertical vent run.

1. Select vent pipe: Use UL standard 1738 approved pipe for category III appliances or appropriately-sealed 26-gauge or heavier galvanized steel or equivalent single-wall pipe. If at least 75% of the vent run is vertical, use double-wall type B vent pipe.
2. Determine vent pipe diameter and length: Minimum vent length is 3 feet (1 meter). Use only one diameter of vent pipe. Refer to Table 4.
3. Determine venter (flue) outlet diameter: Refer to Venter (Flue) Outlet Diameter section.
4. Make vent pipe joint connections: Follow Vent System Sealing section.
5. Support vent pipe runs: Follow Vent System Support Requirements section.
6. Mitigate condensation: Take appropriate steps per Condensation Mitigation section.
7. Terminate vent: Install double-wall type B terminal vent pipe and terminate with option CC1, CC21 vent cap, or Novavent #2NVTB4 vent cap. Refer to Figure 2 for horizontal vent terminal installation and Figure 3 for vertical vent terminal installation. Ensure terminal is installed per Vent Terminal (Type of Pipe and Vent Cap) Requirements.

Figure 2. Horizontal Vent Terminal (Commercial/Industrial Installations)

Diagram shows a horizontal vent terminal with clearances from walls, overhangs, and adjacent structures. Key elements include double-wall vent pipe, vent cap, and pitch for condensate drainage.

Figure 3. Vertical Vent Terminal (Commercial/Industrial Installations)

Diagram shows a vertical vent terminal extending through a roof. Key elements include double-wall vent pipe, roof flashing, vent cap, and minimum height requirements above the roof and snow depth.

Instructions for Residential Installations (Model UDX, Unit Sizes 030, 045, 060, 075, 100, 125)

A Category III vent is required for residential installation of Model UDX units. Venting requirements may vary based on horizontal or vertical installation.

1. Select vent pipe: Use UL standard 1738 approved pipe for category III appliances.
2. Determine vent pipe diameter and length: Minimum vent length is 3 feet (1 meter). Use only one diameter of vent pipe. Refer to Table 4.
3. Determine venter (flue) outlet diameter: Refer to Venter (Flue) Outlet Diameter section.
4. Make vent pipe joint connections: Follow Vent System Sealing section.
5. Support vent pipe runs: Follow Vent System Support Requirements section.
6. Mitigate condensation: Take appropriate steps per Condensation Mitigation section.
7. Terminate vent: Install UL standard 1738 approved category III vent pipe and terminate with option CC1, CC21 vent cap, or Novavent #2NVTB4 vent cap. Refer to Figure 4 for horizontal vent terminal installation and Figure 5 for vertical vent terminal installation. Ensure terminal is installed per Vent Terminal (Type of Pipe and Vent Cap) Requirements section.

Table 4. Vent (Horizontal or Vertical) Pipe Diameters and Lengths

*Add all straight sections and equivalent lengths for elbows—the total combined length must not exceed the maximum vent length.
**Field-supplied taper-type connection required at the venter outlet.
***Refer to APPENDIX B.

Figure 4. Horizontal Vent Terminal (Residential Installations)

Diagram shows a horizontal vent terminal for residential installations, similar to Figure 2 but specifying Category III vent pipe and Option CC1 vent cap.

Figure 5. Vertical Vent Terminal (Residential Installations)

Diagram shows a vertical vent terminal for residential installations, similar to Figure 3 but specifying Category III vent pipe and Option CC1 vent cap.

Instructions for Commercial/Industrial or Residential Installations (Model UDX, Unit Sizes 030, 045, 060, 075, Vertical Category I)

For vertical Category I vents where at least 75% of the equivalent length is vertical and the vent terminates at least 5 feet above the heater outlet. Category I heaters must connect to a chimney or vent complying with a recognized standard or a lined masonry/concrete chimney. Unlined masonry chimneys are not permitted.

1. Select vent pipe: Use standard vertical (category I) vent pipe. Double-wall vent pipe is recommended. Single-wall pipe may be used if National Fuel Gas Code requirements are followed. All pipe must be UL listed for category I appliances.
2. Determine vent pipe diameter and length: Use only one diameter of vent pipe. Refer to Table 4.
3. Determine venter (flue) outlet diameter: Refer to Venter (Flue) Outlet Diameter section.
4. Make vent pipe joint connections: Follow Vent System Sealing section.
5. Support vent pipe runs: Follow Vent System Support Requirements section.
6. Mitigate condensation: Take appropriate steps per Condensation Mitigation section.
7. Terminate vent: Install UL listed category I terminal vent pipe and terminate with option CC1, CC21 vent cap, or Novavent #2NVTB4 vent cap. Refer to Figure 4 for vertical vent terminal installation. Ensure terminal is installed per Vent Terminal (Type of Pipe and Vent Cap) Requirements section.

Appendix A: Instructions for Attaching Double-Wall Type B Vent Pipe to Single-Wall Pipe

NOTE: Work quickly to assemble components before sealant dries.

1. Place a 1/4-inch bead of silicone sealant around the circumference of the single-wall pipe.
2. Insert the single-wall pipe into the inner pipe of the double-wall pipe until the sealant bead contacts the inner pipe to create a sealed joint.
3. Drill three small holes equally spaced around the double-wall pipe below the sealant ring. Secure the joint using 3/4-inch sheet metal screws. Do not overtighten.
4. Place a 3/8-inch bead of silicone sealant around the circumference of the vent cap collar to prevent water from running down the double-wall pipe.
5. Insert the vent cap collar as far as possible inside the inner wall of the double-wall pipe. Apply silicone sealant to close any gaps between the vent cap and double-wall pipe to prevent water entry.
6. Drill a small hole through the vent cap and double-wall pipe. Secure the joint using a 3/4-inch sheet metal screw. Do not overtighten.
7. Place a 1/4-inch bead of silicone sealant around the circumference of the venter outlet collar.
8. Slide the double-wall pipe over the collar so the collar is inside the inner pipe. Push the double-wall pipe tight to the heater cabinet. Drill three small holes through the pipe and into the collar, spaced equally around the pipe below the sealant ring. Secure the joint using 3/4-inch sheet metal screws. Do not overtighten.

Appendix B: Instructions for Installing Flex-L Brand Category III Vent Pipe

NOTES:

• Adapters for Flex-L vent pipe are available from a Flex-L brand vent pipe distributor.
• These instructions are for contractors using Flex-L brand category III vent pipe with a 4-inch (102-mm) venter outlet.
• Work quickly to assemble components before sealant dries.

Components:

• Adapter reducer, Flex-L #SRARZA43, for 3-inch (76-mm) diameter vent pipe (4- to 3-inch, 6-3/4 inches long). Specially-designed for attaching Flex-L brand category III vent pipe to unit sizes 030, 045, and 060.
• Adapter pipe, Flex-L #SRARZA4, for 4-inch (102-mm) diameter vent pipe (4-inch, 12-inch-long). Specially-designed for attaching Flex-L brand category III vent pipe to unit sizes 030, 045, 060, 075, 100, and 125.
• Flex-L brand elbow, attached to 12-inch (305-mm) adapter pipe, extends vent in any direction above horizontal.

1. Attach adapter pipe or reducer to venter collar:

1. Place a continuous bead of high-temperature silicone around the inside of the pipe on the end of the adapter or reducer that attaches to the venter collar.
2. Push the adapter pipe or reducer over the flue collar.
3. Drill a 1/8-inch hole on top of the overlap and secure the joint using a sheet metal screw.

2. Run vent pipe:

1. Determine vent length per installation section requirements.
2. If using a 4- to 3-inch reducer, follow manufacturer's instructions to attach a straight piece of 3-inch pipe or an elbow. If using a 4-inch adapter pipe, follow manufacturer's instructions to attach an elbow or straight pipe.
3. Follow pipe manufacturer's instructions to connect vent pipe sections. The total vent length must not exceed the maximum allowed.
4. Extend vent pipe through wall or roof to outdoors. An approved clearance thimble is required for combustible materials. Comply with local and national codes. The installer is responsible for following manufacturer's instructions and codes.

3. Attach vent cap:

1. Use option CC1 or CC21 vent cap or Novavent #2NVTB4 vent cap.
2. Slide the vent cap collar into the vent pipe.
3. Drill three evenly-spaced 1/8-inch holes around the end of the vent pipe through the pipe and vent cap, and secure the joint using sheet metal screws.