8
PREPARING FOR INSTALLATION
DETERMINING FRESH-AIR FLOW FOR HEATER LOCATION
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 ventilation grills between the rooms.
1.
Determine the volume of the space Length x Width x Height = cu. ft. (volume of space)
2.
If additional ventilation to adjoining rooms is supplied with grills or openings, add the volume of
these rooms to the total volume of the space.
Divide the space 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)
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 heater 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 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).
If 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 Inside Building” on page 9.
b)
Vent room directly to the outdoors. See “Ventilation Air From Outdoors” on page 9.
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.
