Desa CGN20L AIR for Combustion and Ventilation, Determining AIR Flow for Heater Location

BLUE-FLAME CGN20, CGN20L AND RN30D

VENT-FREE NATURAL GAS HEATERS

AIR FOR COMBUSTION AND VENTILATION

Continued

DETERMINING AIR FLOW FOR HEATER 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 heater 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 20 ft. (length) x 16 ft. (width) x 8 ft. (ceiling height) = 2560 cu. ft. (volume of space)

If additional ventilation to adjoining room is supplied with grills or open- ings, 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 sup- port)

Example: 2560 cu. ft. (volume of space) ÷ 50 cu. ft. = 51.2 or 51,200 (maximum Btu/Hr the space can sup- port)

3.Add the Btu/Hr of all fuel burning ap- pliances 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

Example:
Gas water heater		40,000 Btu/Hr
Vent-free heater	+	20,000 Btu/Hr
	=
Total		60,000 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:

51,200 Btu/Hr (maximum the space can support)

60,000 Btu/Hr (actual amount of Btu/Hr used)

The space in the above example is a con- fined 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 ventila- tion grills between rooms. See Ventila- tion Air From Inside Building.

B.Vent room directly to the outdoors. See Ventilation Air From Outdoors, page 5.

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 unconfined space, provide ad- equate combustion and ventila- tion air by one of the methods described in the National Fuel Gas Code, ANSI Z223.1, 1992, Section 5.3 or applicable local codes.

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 pro- vide 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, page 5). You can also remove door into adjoining room (see option 3, Figure 2, page 5). Follow the National Fuel Gas Code NFPA 54/ANSI Z223.1, Section 5.3, Air for Combustion and Ventilation for required size of ventilation grills or ducts.

WARNING: Rework worksheet, adding the space of the adjoining unconfined space. The combined spaces must have enough fresh air to supply all appliances in both spaces.

4 103568