Desa VMH10TPA AIR for Combustion Ventilation, Determining FRESH-AIR Flow for Fireplace Location

® VMH10TPA

VENT-FREE PROPANE/LP GAS COMPACT FIREPLACE

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 fireplace 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 16 ft. (length) x 14 ft. (width) x 8 ft. (ceiling height) = 1792 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 1000 Btu/Hr per 50 cubic feet to determine the maximum Btu/Hr the space can support.

_____________________ (volume of space) x (1000 Btu/Hr ÷ 50 cu. ft.) = (Maximum Btu/Hr the space can support)

Example: 1792 cu. ft. (space volume) x (1000 Btu/Hr ÷ 50 cu. ft.) = 35,840 Btu/Hr. This is the 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	Example:
Gas furnace		______________________ Btu/Hr
			Gas water heater		30,000	Btu/Hr
Vented gas heater		______________________ Btu/Hr	Vent-free fireplace	+	10,000	Btu/Hr
Gas fireplace logs		______________________ Btu/Hr	Total	=	40,000	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 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: 35,840 Btu/Hr (maximum the space can support) 40,000 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, page 7.

B.Vent room directly to the outdoors. See Ventilation Air From Outdoors, page 7.

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 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 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, ANS Z223.1, 1992, Section 5.3 or applicable local codes.

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