Requirements for Unconfined Spaces
Water heaters installed in unconfined spaces do
not usually require outdoor air to function prop-
erly. However, if the water heater is located in an
unconfined space in a building having insufficient
infiltration, air for combustion and additional ventila-
tion should be obtained from the outdoors or from
spaces freely communicating with the outdoors
(see
Figure 2).
Under these conditions, a permanent
opening to the outdoors should be provided so that
the total air received through this opening will be at
least as much as would be admitted by openings hav-
ing a total free-flow area of one (1) square inch per
5,000 BTU/h (4.4 cm
2
/kWh) of the total input rating of
all oil-fired appliances.
Requirements for Confined Spaces (Indoor
Combustion and Ventilation Air)
A water heater that is located in a confined space and
obtains all of its air for combustion and ventilation from
within the conditioned space of the building should be
provided with two permanent openings, one near the
top of the enclosure and another one near the bottom
(see Figure 3).
Each opening should have a free-flow
area of not less than one (1) square inch per 1,000
BTU/h (22 cm
2
/kWh) of the total input rating of all
oil-fired appliances in the enclosure, freely communi-
cating with interior areas that have in turn adequate
infiltration from the outdoors.
Requirements for Confined Spaces (Outdoor
Combustion and Indoor Ventilation Air)
A water heater that is located in a confined space
and that obtains its combustion air from outdoors and
ventilation air from within the conditioned space of
the building should be provided with two permanent
openings, one near the top of the enclosure and
another one near the bottom (see Figures 4 and 5).
Each opening should have a free-flow area of not less
than one (1) square inch per 1,000 BTU/h (22 cm
2
/
kWh) of the total input rating of all oil-fired appliances
in the enclosure, freely communicating with interior
areas that have in turn adequate infiltration from the
outdoors. A combustion air supply opening to the out-
doors should be provided so that the total air received
through the opening will be at least as much as would
be admitted by openings having a total free-flow area
of one (1) square inch per 5,000 BTU/h (4.4 cm
2
/
kWh) of the total input rating of all oil-fired appliances
in the enclosure.
Requirements for Confined Spaces (Outdoor
Combustion and Ventilation Air)
A water heater that is located in a confined space and
that obtains all of its air for combustion and ventila-
tion from outside the building shall be provided with
4
INSTALLATION INSTRUCTIONS
Figure 2
Figure 3
INSTALLATION INSTRUCTIONS
2'' Min.
2'' Min.
2'' Min.
18'' Min.
24'' Min.
2'' Min.
Figure 1
Man inst Oil -GI-IM001En-0211.indd 5
11-10-12 2:11 PM
