Advertisement
-->
EXAMPLE:
(0
2000 altitude)
Heating
value
1050 Bmicu
ft
Specific
gravity
062
Therefore:
Orifice
No. 45
Manifold
pressure
3 6=in
wc
* Furnace
is shipped
with No. 45 orifices.
In this example
all main burner
orifices
are the correct
size and do not need
to be changed
to obtain
the proper
input rate.
Check and verify7 burner
orifice
size in fhnaace. NEVER
ASSUME
ORIFI(E
SIZE; ALWAYS
CHECK
AND VERIFY
2. Adjust
maniibld
pressure
to obtain
input rate
NOTE:
Manifold
pressure
must
always
be measured
with burner
enclosure
fiont REMOVED
Gas meter
must
always
be clocked
with burner
enclosure
front INSTALLED.
a Remove
burner
enclosure
flout.
b. Remove
cap that conceals
adjustment
screw fk_r gas valve
regulator.
(See Fig
46.)
c Jumper
R and W thermostat
connections
on control to start
f_/rnace operation.
d. Turn adjusting
screw,
counterclockwise
(out)
to decrease
manifold
pressure
or clockwise
(in) to increase
manifbld
pressure
NOTE:
This furnace
has been
approved
for a manifold
pressure
of 32 in. wc to 3.8 in. wc when installed
at ahimdes
up to 2000 ft.
For ahimdes
above 2000 ft, the manil:bld
pressure
can be adjusted
from 22 in. wc to 3.8 in. wc. If manifold
pressure
is outside
this
range,
change
burner
orifices
to obtain
pressure
in this range.
tNIT
DAMAGE
HAZARD
Failure
to ibllow
this caution
may result
in reduced
furnace
tifc
DO NOT
bottom
out gas valve
regulator
adjusting
screw
This can result in unregulated
manit\_ld
pressure
and result in
excess
overfire
and heat exchanger
failures.
NOTE:
If orifice
hole appears
damaged
or it is suspected
to have
been
re&illed,
check
orifice
hole with
a numbered
&ill
bit of
correct
size.
Never
re&ill
an orifice.
A burr=fi'ee
and
squarely
aligned
orifice
hole is essential
for proper
flame characteristics.
e. Replace
gas valve regulator
adjustment
screw
cap.
i\ Replace
burner
enclosure
fi'ont
and veri/_
adjusted
gas
input rate using method
outlined
in item 3.
[TNTT DAMAGE
HAZARD
Failure
to follow
t_is
caution
may
result
in component
damage
due
to
flame
impingement
of burners
and
heat
exchangers.
DO NOT
re&ill
orifices.
Improper
&illing
(burrs.
out=of =
round
holes,
etc.)
can
cause
excessive
burner
noise
and
misdirection
of burner
flames.
(See Fig. 47.)
g. Look
through
sight
glass
in burner
enclosure
and check
burner
flame.
Burner
flame
should
be clear blue,
ahnost
tlansparent.
(See Fig. 480
h. Remove
jumper
fiom R and W.
3. Verii}- natural
gas input rate by clocking
gas meter.
NOTE:
Be sure
all pressure
robing,
cornbustion=air
and vent
pipes,
and bunaer enclosure
front are in place when checking
input
by clocking
gas meter.
43
\
%
BURNER
----
ORIFICE
Fig. 47--Burner
Orifice
A93059
a. Calculate
high-altitude
adjustment
(if required).
United
States
At altitudes
above 2000 R, this Nrnace
has been approved
for a 2%
&rate
for each
1000 R above
sea level.
See Table
12 ibr &rate
multiplier
ihctor.
EXAMPLE:
100,000 Btuh input furnace installed at 4300 ft.
Furnace input Rate
Derate
Furnace Input Rate
at Sea Level
X
Multiplier
=
at Installation
Factor
Altitude
100,000
X
0.91
=
91,000
Canada
At installation altitudes fiom 200! to 4500 it, this _:_/macemust be
&rated 5% by an aud_orized Gas (;onve*sion Station. To deter-
mine con'ect input rate for ahimd<
see example above and use
095 as derate multiplier fhctor.
b Reinstall burner box cover.
c. Gas valve
regulator
seal cap MUST
be installed
d
Turn
off all other gas appliances
and pilots.
e
Start furnace
and let operate
for 3 minutes
i_ Measure
time (in sec) ibr gas meter test dial to complete
1
revolution
g. Reibr to Table 13 %r cuft of gas per hr.
h. Multiply gas rate (cu flihr) X heating value (Bmicu it)
using
natural
gas
heating
value
from
local
gas
utility/supplier
Table 12--Ntitude
Derate MuNplier
for U.S.A.
ALTITUDE
{FT}
0--2000
2001--3000
3001--4000
4001--5000
8001--6000
6001--7000
7001--8000
8001--9000
9001--10,000
* Derate multiplierfactoris
% OF
DI=RATE MULTiPLiER
BERATE
FACTOR FOR U.S.A*
0
1.00
4--6
0.95
6--8
0.93
8--10
0.91
10--12
0.89
12--14
0.87
14--16
0.85
16--18
0.83
18--20
0.81
based on midpoint altitude for altitude range.
Advertisement
