8
Vent-Free Gas Log Heater User Manual
Preparing for Installation (cont.)
DETERMINING FRESH-AIR FLOW FOR THE HEATER LOCATION
Determining if You Have a Confined or Unconfined Space:
Use the below information to determine if you have a confined or unconfined space. Your space includes
the room in which you will install the heater plus any other rooms that are directly connected and have
doorless passageways or ventilation grills between the rooms.
1. Determine the volume of the space. Length × Width × Height = cu. ft. (volume of space)
• Example: 20 ft. (length) × 16 ft. (width) × 8 ft. (ceiling height) = 2560 cu. ft. (volume of space)
If additional ventilation to adjoining room(s) is supplied with grills or openings, add the volume of these
rooms to the total volume of your space.
2. Divide the space’s 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 heater _________ BTU/hr
Gas water heater* ________BTU/hr
Gas furnace _____________BTU/hr
Vented gas heater ________BTU/hr Example:
Gas heater logs __________BTU/hr Gas water heater 30,000 BTU/hr
Other gas appl ____BTU/hr Vent-free 26,000 BTU/hr
Total = ____BTU/hr Total = 56,000 BTU/hr
*Do not include direct-vent gas appliances. Direct-vent appliances draw combustion air from outdoors
and vent 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 spa
c
e 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. Add the space of an adjoining room and rework the above information. If the extra space creates an
unconfined spa
c
e, remove the door to the adjoining room or add ventilation grills between rooms.
See VENTILATION AIR FROM INSIDE A BUILDING,
page 9
.
B. Vent the room directly to the outdoors. See VENTILATION AIR FROM OUTDOORS, page 9.
C. Install a heater that uses less BTUs/hr if the lower BTUs/hr creates an unconfined space. If the actual BTU/
hr used is less than the maximum BTU/hr the space can support, the space is an unconfined space. In
this case, no additional fresh air ventilation is needed.
