Air for combustion and ventilation – Desa FPVF33PR User Manual

Page 7

Advertising
background image

7

103280

AIR FOR

COMBUSTION

AND

VENTILATION

Continued

DETERMINING AIR FLOW FOR FIREPLACE 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 fireplace 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. 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:

3168 cu. ft. (volume of space)

÷

50 cu. ft. = 63.3 or 63,300 (maximum

Btu/Hr the space can support)

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

Vent-free fireplace

___________________ 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 fireplace

+

28,000

Btu/Hr

Total

=

68,000

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:

63,300

Btu/Hr (maximum the space can support)

68,000

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 maximum Btu/Hr the space can support. You must provide additional fresh air.
Your options are as follows:

A. Rework work sheet, adding the space of an adjoining room. If the extra space pro-

vides an unconfined space, remove door to adjoining room or add ventilation grills
between rooms. See Ventilation Air from Inside Building, page 8.

B. Vent room directly to the outdoors. See Ventilation Air from Outdoors, page 8.
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 unconfined space. You will need no additional fresh air ventilation.

Continued

Advertising