installed in that space, and an unconfined space as a space whose volume is not less than 50 cubic feet per 1,000 Btu per hour (4.8 m3 per kW) of the aggregate input rating of all appliances installed in that space. Rooms communicating directly with the space in which the appliances are installed*, through openings not fur- nished with doors, are considered a part of the uncon- fined space.
*Adjoining rooms are communication only if there are doorless passageways or ventilation grills be- tween them.
DETERMINING THE TYPE OF HEATER LOCATION SPACE:
Use this method to determine if you have a confined or unconfined space.
Note: the space includes the room in which you install heater plus any adjoining rooms with door- less 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. =
51.8or 51,800 (maximum Btu/hr the space can support)
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, and the space of an adjoining room. If the extra space provides an unconfined 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 unconfined.
If actual Btu/hr used is less than the maximum Btu/ hr the space can support, the space is an uncon- fined space. You will need no additional fresh air ventilation.
VENTILATION AIR
Ventilation from Inside Building
This fresh air would come from an adjoining unconfined space. When ventilation to an adjoining unconfined space, you must provide two permanent openings: one within 12” of the ceiling and one within 12” of the floor on the wall connecting the two spaces (see options 1
&2 of fig. 2). You can also remove door into adjoin- ing room (see option3, fig 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: If the area in which the heater may be operated is smaller than defined as an unconfined space or if the building is of unusually tight con- struction, provide adequate combustion and ventila- tion air by the methods described in the National Fuel Gas Code, NFPA 54/ ANSI Z223.1, Section
5.3or applicable local codes.
3.Add the Btu/hr of all the
Ventilation | Or remove | |
door into | ||
Gills into | ||
Adjoining | ||
Adjoining | ||
Room - | ||
Room - Op- | ||
Option 3 | ||
tion 1 | ||
|
12”
Ventilation Gills into Ad- joining Room - Option 2
*Do not include
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)
12”
Figure 2
WARNING: Rework worksheet, adding the space of the adjoining unconfined space. The combined space must have enough fresh air to supply all ap- pliance in both spaces.
Unvented Liquid Propane Fired Room Heater | 4 | Installation Instructions and Owner’s Manual |
