Raypak 302A-902A manual Support of Vent Stack, Vent Terminal Location

Category III – A heater which operates with a positive vent pressure and with a vent gas temperature that avoids excessive condensate production in the vent.

Category IV – A heater which operates with a positive vent pressure and with a vent gas temperature that may cause excessive condensate production in the vent.

See Table K for appliance category requirements.

NOTE: For additional information on appliance cat- egorization, see appropriate ANSI Z21 Standard and the NFGC (U.S.), or B149.1 (Canada), or applicable provisions of local building codes.

CAUTION: When condensate traps are installed, condensate must be routed to an appropriate con- tainer for neutralization before disposal, as required by local codes.

WARNING: Contact the manufacturer of the vent material if there is any question about the appliance categorization and suitability of a vent material for application on a Category III or IV vent system. Using improper venting materials can result in per- sonal injury, death or property damage.

Support of Vent Stack

The weight of the vent stack or chimney must not rest on the heater vent connection. Support must be pro- vided in compliance with applicable codes. The vent should also be installed to maintain proper clearances from combustible materials.

Use insulated vent pipe spacers where the vent pass- es through combustible roofs and walls.

Vent Terminal Location

NOTE: During winter months check the vent cap and make sure no blockage occurs from build-up of snow or ice.

1.Condensate can freeze on the vent cap. Frozen condensate on the vent cap can result in a blocked flue condition.

2.Give special attention to the location of the vent termination to avoid possibility of property dam- age or personal injury.

3.Gases may form a white vapor plume in winter. The plume could obstruct a window view if the ter- mination is installed near windows.

4.Prevailing winds, in combination with below-freez- ing temperatures, can cause freezing of conden- sate and water/ice build-up on buildings, plants or roofs.

5.The bottom of the vent terminal and the air intake shall be located at least 12 in. above grade, includ- ing normal snow line.

6.Un-insulated single-wall metal vent pipe shall not be used outdoors in cold climates for venting gas- fired equipment.

7.Through-the-wall vents for Category II and IV appliances and non-categorized condensing appli- ances shall not terminate over public walkways or over an area where condensate or vapor could create a nuisance or hazard or could be detrimen- tal to the operation of regulators, relief valves, or other equipment. Where local experience indi- cates that condensate is a problem with Category I and III appliances, this provision shall also apply.

Combustion	Exhaust	Heater Venting	Certified	Combustion Air
Air Supply	Configuration	Category	Materials		Inlet Material
	Vertical Natural	I	“B” Vent
From Inside Building	Draft Venting
(Non-Direct Venting)	Horizontal Through-	III	Stainless Steel
	the-Wall Venting		(Gas Tight)
	Vertical Natural	I	“B” Vent	Galvanized Steel
From Outside Building	Draft Venting				PVC
(Direct Venting)	Horizontal Through-	III	Stainless Steel		ABS
					CPVC
	the-Wall Venting		(Gas Tight)

Table K: Venting Category Requirements

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