Desa VGL18NRA, VGL30PRA installation manual Ventilation AIR, Ventilation Air From Inside Building

AIR FOR COMBUSTION

AND VENTILATION

Continued

Example: Space size 20 ft. (length) x 16 ft. (width) x 8 ft. (ceiling height) = 2,560 cu. ft. (volume of space)

If additional ventilation to adjoining room is supplied with grills or openings, add the volume of these rooms to the total volume of the space.

2.Multiply the space volume by 20 to determine the maximum Btu/Hr the space can support.

__________ (volume of space) x 20 = (Maxi- mum Btu/Hr the space can support)

Example: 2,560 cu. ft. (volume of space) x 20 = 51,200 (maximum Btu/Hr the space can support)

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

Vent-free fireplace	__________ 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. Di- rect-vent draws combustion air from the outdoors and vents to the outdoors.

Example:	40,000
Gas water heater
	__________ Btu/Hr
Vent-free fireplace	39,000
	+ ________ Btu/Hr
Total	79,000
	= ________ Btu/Hr

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.

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.

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)

79,000 Btu/Hr (actual amount of Btu/Hr used)

The space in the example is a confined space because the actual Btu/Hr used is more than the maximum

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

12"

Ventilation Grills

Into Adjoining Room,

Option 2

Btu/Hr the space can support. You must provide ad- ditional 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 Air From Inside Building.

B.Vent room directly to the outdoors. See Ventila- tion Air From Outdoors, page 8.

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

12"

Figure 2 - Ventilation Air from Inside

Building

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