Desa CHL3924NR installation manual Air For Combustion And Ventilation, Continued, Ventilation Air

AIR FOR COMBUSTION

AND VENTILATION

Continued

Example:		40,000
Gas water heater			Btu/Hr
Vent-free fireplace	+_	39,000	Btu/Hr
Total	=_	79,000	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) Example: 51,200 Btu/Hr (maximum the space

can support)

VENTILATION AIR

Ventilation Air From Inside Building

This fresh air would come from an adjoining un- confined space. When ventilating to an adjoining unconfined space, you must provide two perma- nent 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.

79,000 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 maxi- mum 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 adjoin-

ing room. If the extra space provides an unconfined

space, remove door to adjoining room or add

ventilation grills between rooms. See Ventilation

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

12"

Ventilation Grills

Into Adjoining Room,

Option 2

	Air From Inside Building.
B.	Vent room directly to the outdoors. See Ventila-
	tion Air From Outdoors.
C.	Install a lower Btu/Hr fireplace, 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 un- confined space. You will need no additional fresh air ventilation.

WARNING: If the area in which the heater may be oper- ated is smaller than that defined as an unconfined space or if the building is of unusually tight construction, provide adequate combustion and ventilation air by one of the methods described in the National Fuel Gas Code, ANSI Z223.1/NFPA54 Section 5.3 or applicable local codes.

12"

Figure 2 - Ventilation Air from Inside

Building

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.

	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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