Desa VFRMV18PA, VFRMV18NA, VFRMV24NA, VFRMV24PA installation manual Ventilation AIR

AIR FOR COMBUSTION

AND VENTILATION

Continued

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 sup- plied 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 = (Maximum Btu/Hr the space can support)

Example: 2560 cu. ft. (volume of space) x 20 = 51,200 (maximum Btu/Hr the space can support)

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

Vent-free appliance	_________Btu/Hr
Gas water appliance*	_________Btu/Hr
Gas furnace	_________Btu/Hr
Vented gas appliance	_________Btu/Hr
Gas fireplace logs	_________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.

Example:	40,000
Gas water appliance
	_________Btu/Hr
Vent-free appliance	33,000
	+_________Btu/Hr
Total	73,000
	=_________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: 51,200 Btu/Hr (maximum the space can support)

73,000 Btu/Hr (actual amount of Btu/Hr used)

The space in the previous 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.

B.Vent room directly to the outdoors. See Ven- tilation Air From Outdoors, page 8.

C.Install a lower Btu/Hr appliance, 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:Iftheareainwhich the appliance 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, ANSI Z223.1/NFPA54 Section 5.3 or applicable local codes.

VENTILATION AIR

Ventilation Air From Inside Building

This fresh air would come from an adjoining un- confined space. When ventilating to an adjoining unconfined space, you must provide two perma- nent 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 on page 8). You can also remove door into adjoining room (see option 3, Figure 2). Follow the National Fuel Gas Code, ANSI Z223.1/NFPA 54, Section 5.3, Air for Combustion and Ventilation for re- quired size of ventilation grills or ducts.

114745-01B www.desatech.com 7