Desa FPVF33PRA Manuale Utente

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113109-01C

Example:

Gas water heater ______________ Btu/Hr

Vent-free fireplace + _____________ Btu/Hr

Total

= _____________ 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 above example is a confined space

because the actual Btu/Hr used is more than the maxi-

mum 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 adjoin-

ing 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 Ventila-

tion Air From Outdoors.

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 uncon-

fined space. You will need no additional fresh air

ventilation.

WARNING: If the area in which

the fireplace 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/NFPA 54 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

40,000

33,000

73,000

AIR FOR COMbUSTION

AND VENTILATION

Continued

Figure 3 - Ventilation Air from Inside

Building

Remove

Door into
Adjoining

Room,
Option

Ventilation Grills

Into Adjoining Room,

Option 2

Ventilation

Grills

Into Adjoining

Room,

Option 1

12"

the two spaces (see options 1 and 2, Figure 3). You

can also remove door into adjoining room (see

option 3, Figure 3). Follow the National Fuel Gas

Code, ANSI Z223.1/NFPA 54, Section 5.3, Air for

Combustion and Ventilation for required size of

ventilation grills or ducts.

Figure 4 - Ventilation Air from Outdoors

Outlet

Air

Ventilated

Attic

Outlet

Air

Inlet

Air

Inlet Air

Ventilated

Crawl Space

Crawl

Space

To Attic

ventilation Air From Outdoors

Provide extra fresh air by using ventilation grills or

ducts. You must provide two permanent openings:

one within 12" of the ceiling and one within 12"

of the floor. Connect these items directly to the

outdoors or spaces open to the outdoors. These

spaces include attics and crawl spaces. Follow the

National Fuel Gas Code, ANSI Z223.1/NFPA 54,

Section 5.3, Air for Combustion and Ventilation for

required size of ventilation grills or ducts.
IMPORTANT:

Do not provide openings for inlet

or outlet air into attic if attic has a thermostat-

controlled power vent. Heated air entering the attic

will activate the power vent.