Air For Combustion And Ventilation

UNVENTED NATURAL GAS LOG HEATER

WARNING: This heater shall not be installed in a confined space unless provisions are pro- vided for adequate combustion and ventilation air. Read the fol- lowing instructions to insure proper fresh air for this and other fuel-burning appliances in your home.

Today’s homes are built more energy effi- cient than ever. New materials, increased insulation, and new construction methods help reduce heat loss in homes. Home own- ers weather strip and caulk around windows and doors to keep the cold air out and the warm air in. During heating months, home owners want their homes as airtight as pos- sible.

While it is good to make your home energy efficient, your home needs to breathe. Fresh air must enter your home. All fuel-burning appliances need fresh air for proper com- bustion and ventilation.

Exhaust fans, fireplaces, clothes dryers, and fuel burning appliances draw air from the house to operate. You must provide ad- equate fresh air for these appliances. This will insure proper venting of vented fuel- burning appliances.

PROVIDING ADEQUATE VENTILATION

The following is exerpts from National Fuel Gas Code. NFPA 54/ANSI Z223.1, Section 5.3, Air for Combustion and Ventilation.

All spaces in homes fall into one of the three following ventilation classifications:

1.Unusually Tight Construction; 2. Uncon- fined Space; 3. Confined Space.

The information on pages 4 and 5 will help you classify your space and provide ad- equate ventilation.

Unusually Tight Construction

The air that leaks around doors and win- dows may provide enough fresh air for combustion and ventilation. However, in buildings of unusually tight construction, you must provide additional fresh air.

Unusually tight construction is de- fined as construction where:

a.walls and ceilings exposed to the outside atmosphere have a continuous water vapor re- tarder with a rating of one perm (6 x 10-11kg per-pa-sec-m2) or less with openings gasketed or sealed and

b.weather stripping has been added on openable windows and doors and

c.caulking or sealants are ap- plied to areas such as joints around window and door frames, between sole plates and floors, between wall-ceil- ing joints, between wall panels, at penetrations for plumbing, electrical, and gas lines, and at other openings.

If your home meets all of the three criteria above, you must provide ad- ditional fresh air. See Ventilation Air From Outdoors, page 5 .

If your home does not meet all of the three criteria above, proceed to Deter- mining Air Flow For Heater Location.

Confined and Unconfined Space

The National Fuel Gas Code (ANSIZ2123.1, 1992 Section 5.3) defines a confined space as a space whose volume is less than 50 cubic feet per 1,000 Btu per hour (4.8 m3 per kw) of the aggregate input rating of all appliances installed in that space and an unconfined space as a space whose volume is not less than 50 cubic feet per 1,000 Btu per hour (4.8 m3 per kw) of the aggregate input rating of all appliances installed in that space. Rooms communicating directly with the space in which the appliances are in- stalled*, through openings not furnished with doors, are considered a part of the unconfined space.

*Adjoining rooms are communicating only if there are doorless passageways or ventila- tion grills between them.

DETERMINING AIR FLOW FOR HEATER LOCATION

Determining if You Have a Confined or Unconfined Space

Use this work sheet 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 support)

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 +		33,000 Btu/Hr
	=
Total	=	73,000 Btu/Hr

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

Continued

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