Monessen Hearth BTU/Hr Benutzerhandbuch

8                                                                                                                                                                                   

9

DETERMINING IF YOU HAVE A CONFINED OR UNCONFINED SPACE 
Use this worksheet to determine if you have a confined or unconfined space.
Space: Includes the room in which you will install heater plus any adjoining rooms with doorless passageways or ventila-
tion grills between the rooms.
1.   Determine the volume of the space (length x width x height). 
 

Length x Width x Height = ____________________ cu. ft. (volume of space) 

 

Example: Space size 20 ft. (length) x 16 ft. (width) x 8 ft. (ceiling height) = 2560 cu. ft. (volume of space) 

 

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 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 x 1000 = 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

 

Gas fireplace logs  

_______________ Btu/Hr

 

Other gas appliances*  +  _______________ Btu/Hr

 

Total 

 =  _______________ Btu/Hr

 

*    Do  not  include  direct-vent  gas  appliances.  Direct-vent  draws  combustion  air  from  the  outdoors  and  vents  to 

the out-doors.

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)

 

 

60,000 Btu/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 Outdoors,” page 10.

B.   Vent room directly to the outdoors. See “Ventilation Air From Outdoors,” page 10.
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.

Example:
Gas water heater   30,000   Btu/Hr
Vent-free heater   +  30,000   Btu/Hr
Total  

=  60,000   Btu/Hr