AIR for Combustion Ventilation | Vanguard FBST instruction

AIR FOR COMBUSTION

AND VENTILATION

Continued

Unusually tight construction is defined as con- struction where:

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

b.weather stripping has been added on open- able windows and doors and

c.caulking or sealants are applied to areas such as joints around window and door frames, between sole plates and floors, between wall-ceiling joints, between wall panels, at penetrations for plumbing, elec- trical and gas lines and at other openings.

If your home meets all of the three criteria above, you must provide additional fresh air. See Ventilation Air From Outdoors, page 7.

If your home does not meet all of the three cri- teria above, proceed to Determining Fresh-Air Flow for Firebox Location.

Confined and Unconfined Space

The National Fuel Gas Code ANS Z223.1/NFPA 54 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 com- municating directly with the space in which the appliances are installed*, through openings not furnished with doors, are considered a part of the unconfined space.

This heater shall not be installed in a confined space or unusually tight construction unless provi- sions are provided for adequate combustion and ventilation air.

*Adjoining rooms are communicating only if there are doorless passageways or ventilation grills between them.

DETERMINING FRESH-AIR FLOW FOR Firebox 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 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.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: 3168 cu. ft. (volume of space) x 20 = 63,360 (maximum Btu/Hr the space can support)

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

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		40,000	Btu/Hr
Gas firebox logs	+	39,000	Btu/Hr
Total	=	79,000	Btu/Hr

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: 63,360 Btu/Hr (maximum the space

can support)

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