Desa GWP6 Ventilation AIR, Ventilation Air From Inside Building, Ventilation Air From Outdoors

AIR FOR COMBUSTION AND VENTILATION

Continued

3.Add the Btu/Hr of all fuel burning appliances in the space.

Vent-free heater		_____________ Btu/Hr
Gas water heater*		_____________ Btu/Hr
Gas furnace		_____________ Btu/Hr
Vented gas heater		_____________ Btu/Hr
Gas fireplace logs		_____________ Btu/Hr
Other gas appliances* +		_____________ Btu/Hr
Total	=	_____________ Btu/Hr

*Do not include direct-vent gas appliances. Direct-vent draws com- bustion air from the outdoors and vents to the outdoors.

Example:
Gas water heater		40,000
		_____________ Btu/Hr
Vent-free heater	+	10,000
		_____________ Btu/Hr
Total	=	50,000
		_____________ Btu/Hr

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)

__________________ Btu/Hr (actual amount of Btu/Hr used)

AIR FOR COMBUSTION AND VENTILATION	5
Determining Fresh-Air Flow For Heater Location
Ventilation Air

VENTILATION AIR

Ventilation Air From Inside Building

This fresh air would come from an adjoining unconfined space. When ventilating to an adjoining unconfined space, you must provide two permanent openings: one within 12" of the ceiling and one within 12" of the floor on the wall connecting the two spaces (see options 1 and 2, Figure 2). You can also remove door into adjoining room (see option 3, Figure 2). Follow the National Fuel Gas Code, ANSI Z223.1/NFPA 54, Section 5.3, Air for Combustion and Ventilation for required size of ventilation grills or ducts.

Ventilation Air From Outdoors

Provide extra fresh air by using ventilation grills or ducts. You must provide two permanent openings: one within 12" of the ceiling and one within 12" of the floor. Connect these items directly to the outdoors or spaces open to the outdoors. These spaces include attics and crawl spaces. Follow the National Fuel Gas Code, ANSI Z223.1/NFPA 54, Section 5.3, Air for Combustion and Ventilation for required size of ventilation grills or ducts.

IMPORTANT: Do not provide openings for inlet or outlet air into attic if attic has a thermostat-controlled power vent. Heated air entering the attic will activate the power vent.

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/ Hr used is more than the maximum Btu/Hr the space can support. You must provide additional fresh air. Your options are as follows:

A.	Rework worksheet, adding the space of an adjoining room. If the
	extra space provides an unconfined space, remove door to adjoining
	room or add ventilation grills between rooms. See Ventilation Air From
	Inside Building.
B.	Vent room directly to the outdoors. See Ventilation Air From Outdoors.

Ventilation
Grills	Or
into Adjoining	Remove
Room,	Door into
Option 1	Adjoining
	Room,
	Option 3

12"

Ventilation Grills

Into Adjoining Room,

Option 2

C. Install a lower Btu/Hr heater, if lower Btu/Hr size makes room unconfined.

If the actual Btu/Hr used is less than the maximum Btu/Hr the space can support, the space is an unconfined space. You will need no additional fresh 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.

12"

Figure 2 - Ventilation Air from Inside Building

Ventilated

Outlet Attic

Air

Outlet
Air	To Attic

To

Crawl

Space

Inlet

Air

Inlet Air	Ventilated
	Crawl Space

Figure 3 - Ventilation Air from Outdoors

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