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EXAMPLE: Gas Water Heater 40,000 BTU/Hr
Vent-Free Heater +18,000 BTU/Hr
TOTAL = 58,000 BTU/Hr
*DOES NOT INCLUDE DIRECT-VENT GAS APPLIANCES. DIRECT-VENT DRAWS
COMBUSTION AIR FROM 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: 51200BTU/Hr (maximum the space can support)
58000BTU/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 21.
B. Vent room directly to the outdoors . See “Ventilation Air Outdoors”, page 22.
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.
WARNING
YOU MUST PROVIDE ADDITIONAL
VENTILATION AIR IN A CONFINED SPACE
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