42
T
ABLE
12
SUPPLEMENT
AL
ORIFICE
SIZE
CHAR
T
90
Plus
ONL
Y
models
with
15,000
Btu's
per
Burner
.
DO
NO
T
USE
THIS
CHAR
T
FOR
ANY
80
PLUS
MODEL.
NA
TURAL
GAS
QUICK
REFERENCE
CHAR
T
FOR
ORIFICE
SELECTION,
A
T
3.5"
W
.C.
AND
APPROXIMA
TE
FINAL
FIRING
RA
TES
Final
Firing
Rate
per
Burner
Sea
Level
Orifice
Size
Sea
Level
Cubic
Foot
at
3.5"
W
.C.
90
Plus
Heat
V
alue
at
15,000
Btu’
s
per
Burner
0-999
1000-1999
2000-2999
3000-3999
4000-4999
5000-5999
6000-6999
7000-7999
8000-8999
9000-9999
ELEV
A
TION
CHAR
T
(National
Fuel
Gas
Code
recommended
orifice
based
on
4%
derate
for
each
1000
foot
of
elevation,
based
on
the
intersection
of
the
orifice
required
at
Sea
Level
and
the
elevation
required
below)
46
18.57
808
46
46
47
47
47
48
48
49
49
50
47
17.52
856
47
47
48
48
49
49
49
50
50
51
48
16.36
917
48
48
49
49
49
50
50
50
51
51
49
15.2
987
49
49
50
50
50
51
51
51
52
52
50
13.92
1078
50
50
51
51
51
51
52
52
52
53
51
12.77
1
175
51
51
51
52
52
52
52
53
53
53
15,000
14,400
13,800
13,200
12,600
12,000
1
1,400
10,800
10,200
9,600
All
calculations
are
perf
ormed
b
y
using
the
fir
st
three
columns
of
inf
ormation
onl
y
.
Bef
ore
beginning
an
y
calculations,
determine
the
individual
b
urner
Btu
siz
e
and
heating
v
alue
at
Sea
Le
vel
for
the
installation
site
.
Eac
h
v
alue
sho
wn
in
the
Heat
V
alue
column
is
per
b
urner
at
3.5"
W
.C.
NO
TE:
Heat
V
alue
at
Sea
Level,
for
the
location
of
the
installation,
is
available
from
the
Natural
Gas
Supplier
to
that
site.
Orifices
for
all
altitudes
are
based
on
Sea
Level
values.
Divide
the
individual
burner
capacity
(15,000
for
90
plus)
by
the
Heat
V
alue
for
the
site
to
determine
the
Cubic
Foot
value
at
Sea
Level,
or
divide
burner
capacity
by
the
Cubic
Foot
value
for
the
Heat
V
alue.
Once
you
have
either
the
Cubic
Foot
V
alue
or
the
Heat
V
alue
you
can
estimate
the
Sea
Level
orifice
for
the
site.
T
o
select
the
corresponding
high
altitude
orifice,
locate
the
site
elevation
on
the
chart
above
and
the
orifice
required
at
Sea
Level
from
your
calculation
in
the
first
column.
The
correct
high
altitude
orifice
that
must
be
installed
in
each
individual
burner
is
the
intersection
of
these
two
points
on
the
chart
above.
