Desa Tech CGN20TA User Manual

5

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Use this worksheet to determine if you have
a confined or unconfined 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       + 20,000 Btu/Hr
Total                        = 60,000 Btu/Hr

* Do not include direct-vent gas appli-
ances. 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:

  51,200 Btu/Hr (maximum

the space can support)60,000 Btu/Hr
(actual amount of Btu/Hr used)

The space in the above example is a con-
fined 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 ventila-
tion grills between rooms. See Ventila-
tion Air From Inside Building, page 6.

B. Vent room directly to the outdoors. See

Ventilation Air From Outdoors, page 6.

C. Install a lower Btu/Hr heater, 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.