Use and Care Manual
Installation Instructions and Owner’s Manual
Unvented LP-Gas Vent Free Room Heaters
5
*Adjoining rooms are communication only if there 
are odorless passageways or ventilation grills 
between them.
DETERMINING THE TYPE OF HEATER 
LOCATION SPACE:
Use this method to determine if you have a conned or 
unconned space.
Note: the space includes the room in which you 
install heater plus any adjoining rooms with doorless 
passageways or ventilation grills between the rooms.
1. Find the volume of the space by multiplying room 
length x width x height.
Example: Space size 18ft (length) x 18ft. (width) x 8ft. 
  (height) = 2592
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 deter-
mine the maximum Btu/hr the space can support.
Example: 2592 cu.ft. (volume of space) / 50 cu.ft. = 
  51.8 or 51,800 (maximum Btu/hr the space 
  can support)
WARNING: If the area in which the heater may be 
operated is smaller than dened as an unconned 
space or if the building is of unusually tight 
construction, provide adequate combustion and 
ventilation air by the methods described in the 
National Fuel Gas Code, NFPA 54/ ANSI Z223.1, 
Section 5.3 or applicable local codes. 
3. Add the Btu/hr of all the fuel-burning appliances 
in the space such as, Vent–free heater, Gas water 
heater, Gas furnace, Vented gas heater, Gas 
replace logs, and Other gas appliances*
*Do not include direct-vent gas appliances. Direct-
vent draws combustion air from the outdoors and 
vents to the outdoors.
Example:  Gas water heater  40,000 Btu/hr
    Vent Free Heater +  20,000 Btu/hr
    Total      =60,000 Btu/hr
4. Compare the maximum Btu/hr the space can support 
with the actual amount of Btu/hr used.
Example:  51,800 Btu/hr (maximum Btu/hr the 
    space can support)
    60,000 Btu/hr (Actual amount of Btu/hr 
    used)
The space in the above example is a conned 
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, and the space of an adjoining 
room. If the extra space provides an unconned 
space, remove door to adjoining room or add 
ventilation grills between the rooms. See Ventilation 
Air From Inside Building (Figure 2).
B. Vent room directly to the outdoors. See Ventilation 
Air From Outdoors (Figure 3). 
C. Install a lower Btu/hr heater if lower Btu/hr size 
makes room unconned. 
If actual Btu/hr used is less than the maximum Btu/
hr the space can support, the space is an uncon-
ned space. You will need no additional fresh air 
ventilation.
VENTILATION AIR
Ventilation from Inside Building
This fresh air would come from an adjoining unconned 
space. When ventilation to an adjoining unconned 
space, you must provide two permanent openings: one 
within 12” of the ceiling and one within 12” of the oor 
on the wall connecting the two spaces (see options 1 
& 2 of g. 2). You can also remove door into adjoin-
ing room (see option3, g 2). Follow the National Fuel 
Gas Code NFPA 54/ ANSI Z223.1, Section 5.3, Air for 
Combustion and Ventilation for required size of ventila-
tion grills or ducts.
Figure 2.
Figure 3.
Ventilation 
Gills into 
Adjoining 
Room - 
Option 1
Ventilation Gills into 
Adjoining Room - Option 2
12”
12”
Or remove 
door into 
Adjoining 
Room - 
Option 3
INLET 
AIR
OUTLET 
AIR
VENTILATION CRAWL SPACE
TO CRAWL 
SPACE
TO ATTIC
VENTILATION AIR
VENTILATED 
ATTIC
OUTLET AIR










