Sterling GG-105, GG-90 SEPARATED COMBUSTION VENTING continued, Concentric Vent Box Dimensions

SEPARATED COMBUSTION

VENTING (continued)

4.Use single wall pipe constructed of 26 GA galvanized steel or a material of equivalent durability and corrosion resistance for the vent system. For installations in Canada, use corrosion resistant and gas-tight, listed vent pipe conforming with local building codes, or in the absence of local building codes, with current CAN/CGA-B149.1, Installation Codes for Natural Gas Burning Appliances and Equipment or CAN/ CGA-B149.2, Installation Codes for Propane Gas Burning Appliances and Equipment. For residential installations in the United States, vent pipe approved for Category III appliances must be used between the appliance and the concentric vent box unless 33% of the vent run is vertical, then single wall galvanized vent pipe or double wall Type B vent pipe may be used between the appliance and the concentric vent box. A single length of double wall Type B vent pipe must be used to go through the concentric vent box and outside wall to the vent terminal.

5.Any run of single wall vent pipe passing through an unheated space must be insulated with an insulation

NOTICE: Increasing the clearance distances may be necessary if there is a possibility of distortion or discoloration of adjacent materials.

11.The top of a VERTICALLY VENTED exhaust system must extend at least 3 feet (0.91m) above the roof surface that it passes through. See Figure 22.

12.The point of termination for a HORIZONTALLY VENTED exhaust system must be at least 12 inches (0.3m) from the exterior of the wall that it passes through. In addition, the termination point must be at least 1 foot (0.3m) above grade or above the snow line, more than 6 feet (1.8m) from the combustion air inlet of another appliance, at least 4 feet (1.2m) below, 4 feet (1.2m) horizontally from, or 1 foot (0.3m) above any door, window or gravity air inlet into any building, and more than 3 feet (0.91m) from and not directly above, any gas meter or service regulator. See Figures 23 and 24 and Table 4.

	suitable to 550° F.		Table 6 - Concentric Vent Box Dimensions
6.	The vent system must be installed to prevent
			Unit		Dimensions - Inches (Nominal)
	collection of condensate. Pitch horizontal pipes
	downward 1/4 inch per foot (21mm per meter) toward		Size	A	B	C	D	E	G
			30
	the vent cap to facilitate drainage. Vertical vent pipes
	should be piped as depicted in Figure 22.		45	41/2	4	6	8	5	12
7.	The equivalent length of the vent system must not be		60
	less than 5 feet (1.5m) and must not exceed 30 feet		75
	(9m). The equivalent length equals the total length		90
	of straight pipe plus 5 feet (1.5m) for each 90° elbow
			105	51/2	5	8	12	5	15
	and 2.5 feet (0.76m) for each 45° elbow.		120
8.	Each slip joint must be secured with at
	least three corrosion resistant screws.
	Two full turns of 3M #425 Aluminum Foil	Figure 20 - Concentric Vent Box
	tape or its equivalent must then be used
	to seal each joint. High temperature
	silicone sealant may be used instead of
	the tape. Silicone sealant must be used
	to seal the joint between the Type B vent
	pipe and the single wall pipe.
9.	For horizontal vent systems longer
	than 5 feet (1.5m), the system must
	be supported from overhead building
	structures at 4 foot (1.2m) intervals in
	the U.S. and at 3 foot (0.91m) intervals in
	Canada.
10.	The exhaust vent system must remain
	at a minimum distance of 1 inch (25mm)
	from all combustible materials. Any part
	of the vent system that passes through
	a combustible material must be properly
	insulated.

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