Filter
Top Products
7
Vermont Castings Radiance
3. Add the BTU/Hr ratings of all fuel-burning appli-
ances installed in the same space, including the
following:
Gas Water Heater Gas Furnace
Gas Fireplace Logs Unvented Gas Heater
Vented Gas Heater* Other Gas Appliances*
* Do not include Direct Vent appliances as these
utilize outside air for combustion and vent to the
outdoors.
Example:
Gas Range 55,000 BTU/Hr
Unvented Heater +33,000 BTU/Hr
Total 88,000 BTU/Hr
4. Compare the maximum BTU/Hr rating the space can
support with the total BTU/Hr used by the appliances.
Example:
76,800 BTU/Hr - max. the space can support
88,000 BTU/Hr - total used by appliances
In this example, the maximum BTU/Hr that the
space can support is less than the total used by the
appliances, the space is considered to be
Confined
space
. Additional air must be provided to meet the
requirements of the Unvented heater.
A confined space may be ventilated in two ways:
A) Open up or provide at least two ventilating grilles
to an adjoining unconfined space. Use any of the
options illustrated in Figure 4.
Each of the two grilles must provide an opening of
at least 50 square inches, with all opening dimensions
being at least 3". One grille must be located within 12"
of the ceiling; the other within 12" of the floor. (If the
total exceeds 100,000 BTU/Hr, additional grilles will be
required.)
B) Vent the room directly to the outdoors. (Provide
one square inch of opening for each 4,000 BTU/hr.
If the total BTU/Hr used by the appliances is less
than the maximum BTU/Hr the space is able to sup-
port, the room meets the Unconfined space
criteria and
no further ventilation is required.
For further information on ventilation guidelines
and sizing specifications follow the National Fuel Gas
Code NFPA 54/ANSI Z223.1 Section 5.3.
IF THE AREA IN WHICH THE HEATER MAY BE
OPERATED IS SMALLER THAN THAT DEFINED
AS AN UNCONFINED SPACE, PROVIDE
ADEQUATE COMBUSTION AND VENTILATION AIR
BY ONE OF THE METHODS DESCRIBED IN THE
NATIONAL FUEL GAS CODE, ANSI Z223.1, 1992,
SECTION 5.3.
THIS HEATER SHALL NOT BE INSTALLED IN A
CONFINED SPACE UNLESS PROVISIONS ARE
PROVIDED FOR ADEQUATE COMBUSTION AND
VENTILATION AIR.
WARNING
12”
12”
Option 3 -
Vents to Adjoining
Room
Option 1
Vents to
Adjoining
Room
Option 2 -
Remove
Door
between
Adjoining
Rooms
ST184
Fig. 4 Vent options to provide additional air.