Thomas & Betts LDAP 1200 Venting cont’d, Venting Requirements cont’d, 4Joints and Sealing cont’d

24.Venting (cont’d)

Venting Requirements (cont’d)

4)Joints and Sealing (cont’d)

FIGURE 17C - Attaching Double-Wall (Type B) Terminal Pipe to a Single Wall or Category III Vent

Figure 17C - STEP 1

On the single-wall pipe or Category III pipe, place a continual

1/4 inch bead of silicone sealant around the circumference.

Do STEP 2 immediately after STEP 1.

Single-

Wall or

Category

III Vent

Pipe

Figure 17C - STEP 2

Insert the pipe with the sealant into the inner pipe of the double-wall pipe until the bead of sealant contacts the inner pipe creating a sealed joint.

Double-	Vent
Wall	Pipe
Pipe	with
	Sealant

Pipe Run

Figure 17C - STEP 3

Spaced equally around the double-wall pipe, drill three small holes below the sealant ring. Insert 3/4 inch long sheetmetal screws to secure the joint. Do not over tighten screws.

5)Vent System Support

6)Condensation

7)Vent Terminal (Pipe and Vent Cap)

Support horizontal vent runs every six feet (1.8M). Support vertical runs of Type “B” double-wall or Category III vent pipe in accordance with the requirements of the pipe manufacturer. Support single-wall pipe in accordance with accepted indus- try practices. Do not rely on the heater for support of either horizontal or vertical vent pipe. Use non-combustible supports on vent pipe.

Any length of single-wall vent pipe exposed to cold air or run through an unheated area or an area with an ambient temperature of 45°F or less must be insulated along its entire length with a minimum of 1/2" foil-faced fiberglass, 1-1/2# density insu- lation. Where extreme conditions are anticipated, install a means of condensate disposal.

The vent terminal pipe must be either Category III vent pipe or double-wall (Type B). Heaters must be equipped with a Reznor vent cap, a Type L Breidert Air-x- hauster® vent cap or equivalent. A different style vent cap could cause nuisance problems or unsafe conditions. The vent cap must be the same diameter as the vent pipe.

See the clearance table below and FIGURE 18 for requirements of a horizontal vent terminal. See FIGURE 19 for requirements of vertical vent termination.

Horizontal Vent Terminal Clearances

A vent cap is required. Maintain a minimum clearance of 12 inches (305mm) from the wall to the vent terminal cap for stability under wind conditions.

Products of combustion can cause discolora- tion of some building finishes and deteriora- tion of masonry materials. Applying a clear silicone sealant that is normally used to pro- tect concrete driveways can protect masonry materials. If discoloration is an esthetic prob- lem, relocate the vent or install a vertical vent.

Form RZ-NA-I-LDAP, P/N 207733 (Rev 2), Page 28

Structure	Minimum Clearances for Vent Termination
	Location (all directions unless specified)
Forced air inlet within 10 ft (3.1M)	3 ft (0.9M) above
Combustion air inlet of another appliance	6 ft (1.8M)
Door, window, or gravity air inlet (any	4 ft (1.2M) horizontally
building opening)	4 ft (1.2M) below
	1 ft (305mm) above
Electric meter, gas meter*, gas regulator*,	U.S. - 4 ft (1.2M) horizontally
and relief equipment	Canada - 6 ft (1.8M) horizontally)
Gas regulator *	U.S. - 3 ft (0.9M); Canada - 6 ft (1.8M)
Adjoining building or parapet	6 ft (1.8M)
Adjacent public walkways	7 ft (2.1M) above
Grade (ground level)	1 ft (305mm) above**

*Do not terminate the vent directly above a gas meter or service regulator.

** Consider local snow depth conditions. The vent must be at least 6” (152mm) higher than anticipated snow depth.