Desa VN10A AIR for Combustion, Ventilation AIR, Ventilation Air From Inside Building

AIR FOR COMBUSTION AND VENTILATION	5
Determining Fresh-Air Flow For Heater Location (Cont.)
Ventilation Air

AIR FOR COMBUSTION AND				VENTILATION AIR
VENTILATION				Ventilation Air From Inside Building
Continued				This fresh air would come from an adjoining unconfined space.
3. Add the Btu/Hr of all fuel burning appliances in the space.				When ventilating to an adjoining unconfined space, you must
				provide two permanent openings: one within 12" of the ceiling and
	Vent-free heater		_____________ Btu/Hr	one within 12" of the floor on the wall connecting the two spaces
	Gas water heater*		_____________ Btu/Hr	(see options 1 and 2, Figure 2). You can also remove door into
	Gas furnace		_____________ Btu/Hr	adjoining room (see option 3, Figure 2). Follow the National Fuel
	Vented gas heater		_____________ Btu/Hr	Gas Code, ANSI Z223.1/NFPA 54, Section 5.3, Air for Combustion
	Gas fireplace logs		_____________ Btu/Hr	and Ventilation for required size of ventilation grills or ducts.
	Other gas appliances* +		_____________ Btu/Hr
	Total	=	_____________ Btu/Hr			12"
	* Do not include direct-vent gas appliances. Direct-vent draws com-
	bustion air from the outdoors and vents to the outdoors.						Ventilation Grills
	Example:
				Ventilation			Into Adjoining Room,
	Gas water heater		40,000		Or		Option 2
				Grills
			_____________ Btu/Hr	into Adjoining	Remove
			10,000
	Vent-free heater	+		Room,	Door into
			_____________ Btu/Hr	Option 1	Adjoining
	Total	=	50,000		Room,
			_____________ Btu/Hr		Option 3
4.	Compare the maximum Btu/Hr the space can support with the actual
	amount of Btu/Hr used.
	__________________ Btu/Hr (maximum the space can support)
					12"
	__________________ Btu/Hr (actual amount of Btu/Hr used)
	Example: 51,200 Btu/Hr (maximum the space can support)
	50,000 Btu/Hr (actual amount of Btu/Hr used)
The space in the above example is a confined space because the actual Btu/				Figure 2 - Ventilation Air from Inside Building
Hr used is more than the maximum Btu/Hr the space can support. You must
				Ventilation Air From Outdoors
provide additional fresh air. Your options are as follows:
A.	Rework worksheet, adding the space of an adjoining room. If the ex-			Provide extra fresh air by using ventilation grills or ducts. You must

tra space provides an unconfined space, remove door to adjoining	provide two permanent openings: one within 12" of the ceiling and
room or add ventilation grills between rooms. See Ventilation Air From
	one within 12" of the floor. Connect these items directly to the
Inside Building.
	outdoors or spaces open to the outdoors. These spaces include attics

B.Vent room directly to the outdoors. See Ventilation Air From and crawl spaces. Follow the National Fuel Gas Code, ANSI Z223.1/

Outdoors.	NFPA 54, Section 5.3, Air for Combustion and Ventilation for
C. Install a lower Btu/Hr heater, if lower Btu/Hr size makes room un-	required size of ventilation grills or ducts.
confined.	IMPORTANT: Do not provide openings for inlet or outlet air into
If the actual Btu/Hr used is less than the maximum Btu/Hr the space can	attic if attic has a thermostat-controlled power vent. Heated air
support, the space is an unconfined space. You will need no additional fresh	entering the attic will activate the power vent.
air ventilation.

WARNING: If the area in which the heater may be operated is smaller than that defined as an uncon- fined space or if the building is of unusually tight construction, provide adequate combustion and ven- tilation air by one of the methods described in the National Fuel Gas Code, ANSI Z223.1/NFPA 54, Sec- tion 5.3 or applicable local codes.

	Outlet	Ventilated
		Attic
	Air
Outlet
Air
					To Attic
					To
					Crawl
Inlet					Space
Air
	Inlet Air			Ventilated
			Crawl Space

Figure 3 - Ventilation Air from Outdoors

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