Operating instructions
5
Installation Instructions and Owner’s Manual
Unvented Natural Gas Fired Room Heater
attics* and crawl spaces. Follow the National Fuel Gas 
Code NFPA 54/ ANSI Z223.1, Section 5.3, Air for Com-
bustion and Ventilation for required size of ventilation 
grills or ducts.
*IMPORTANT: Do not provide openings for inlet or 
outlet into attic. If attic has a thermostat-controlled 
power vent, heated air entering the attic will activate 
the power vent.
IMPORTANT: Vent-free heaters add moisture to 
the air. Although this is benecial, installing heater 
in rooms without enough ventilation air may cause 
mildew to form from too much moisture. See Fresh 
Air for Combustion and Ventilation, pages 4  
through 6. 
INSTALLATION
NOTICE: This heater is intended for the use as supple-
mental heat. Use this heater along with your primary 
heating system. Do not install this heater as your pri-
mary heat source. If you have a central heating system, 
you may run system’s circulating blower while using 
heater. This will help circulate the heat throughout the 
house. In the event of a power outage, you can use this 
heater as your primary heat source for the duration of 
the outage. 
heater, Gas furnace, Vented gas heater, Gas re-
place 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 venti-
lation grills between the rooms. See Ventilation Air 
From Inside Building (Fig. 2)
B. Vent room directly to the outdoors. See Ventilation 
Air From Outdoors (Fig. 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 gure 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.
 WARNING: Rework worksheet, adding the space 
of the adjoining unconned space. The combined 
space must have enough fresh air to supply all ap-
pliance in both spaces. 
Ventilation from Outdoors
If necessary provide extra fresh air by using ventila-
tion grills or ducts. Connect these items directly to the 
outdoors or spaces open to the outdoors. These include 
Ventilation 
Gills into 
Adjoining 
Room - Op-
tion 1
Ventilation Gills into Ad-
joining 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
Figure 2
Figure 3.










