Desa Tech CGFB32C Combustion Ventilation, Determining FRESH-AIR Flow for Fireplace Location

OWNER'S MANUAL

AIR FOR

COMBUSTION AND

VENTILATION

Continued

DETERMINING FRESH-AIR FLOW FOR FIREPLACE LOCATION

Determining if You Have a Confined or Unconfined Space

Use this worksheet to determine if you have a confined or unconfined space.

Space: Includes the room in which you will install firebox plus any adjoining rooms with doorless passageways or ventilation grills between the rooms.

1.Determine the volume of the space (length x width x height).

Length x Width x Height	=	cu. ft. (volume	of space)
Example:Space size 22	ft. (length)	x 18 ft. (width) x 8 ft. (ceiling	height) = 3168 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.Divide the space volume by 50 cubic feet to determine the maximum Btu/Hr the space can support. (volume of space) + 50 cu. ft. = (Maximum Btu/Hr the space can support)

Example: 3168 cu. ft. (volume of space) .'- 50 cu. ft. = 63.3 or 63,300 (maximum Btu/Hr the space can support)

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

Vent-free		firebox	Btu/Hr
Gas water		heater*	Btu/Hr	Example:
Gas furnace			Btu/Hr	Gas water	heater	40,000	Btu/Hr
Vented	gas heater		Btu/Hr	Vent-free	firebox with log heater +	39,000	Btu/Hr
Gas firebox logs			Btu/Hr	Total		79,000	Btu/Hr
Other	gas appliances* +		Btu/Hr
Total		=	Btu/Hr

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

4.Compare the tnaximum Btu/Hr the space can support with the actual amount of Btu/Hr used.

Btu/l-lr (maximum the space can support)

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

Example: 63,300 Btu/Hr (maximum the space can support) 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 maximum Btu/Hr the space can support. Yon 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 adjoin- ing room or add ventilation grills between rooms. See Ventilation Air From Inside Building, page 6.

B.Vent room directly to the outdoors. See Ventilation Air From Outdoors, page 6.

C.Install a lower Btu/Hr fireplace, if lower Btu/I-Ir 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.

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_lb WARNING: If the area In which the firebox end gas log heater may be operated is smeller than that defined as I an unconfined space or If the building Is of unusually tight construction, provide adequate combustion and I ventilation air by one of the methods described in the National Fuel Gas Code, ANS Z223.1, 1992, Section 5.3 or eppllceble local codes.

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