Procom PC32VFC Manual page 7

2. Divide the space volume by 50 cu. ft. 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 support)
3. Add the BTU/hr of all fuel burning appliances in the space.
Vent-free fireplace
Gas water fireplace*
Gas furnace
Vented gas fireplace
Gas fireplace logs
Other gas appliances*+ BTU/hr
Total
*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: 51,200 BTU/hr (maximum the space can support)
56,000 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 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," 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.
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, Air for Combustion and
Ventilation, or applicable local codes.
WARNING: If the area in which the fireplace may be operated does not meet the required volume for indoor
combustion air, combustion and ventilation air shall be provided by one of the methods described in the
NATIONAL FUEL GAS CODE, ANSI Z223.1/NFPA 54, the INTERNATIONAL FUEL GAS CODE, or applicable
local codes.
_____________ BTU/hr
_____________ BTU/hr
_____________ BTU/hr
_____________ BTU/hr
_____________ BTU/hr
= _____________ BTU/hr
Example:
Gas water fireplace
Vent-free fireplace + 26,000 BTU/hr
Total =
7
30,000 BTU/hr
56,000 BTU/hr