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II. START UP HEATING SECTION AND MAKE
ADJUSTMENTS
Do not jumper
any
safety
devices
when
operating
the
unit.
Make
sure
that
burner
orifices
are
properly
aligned.
Un
stable
operation
may
occur
when
the
burner
orifices
in the
manifold
are
misaligned.
Follow
the lighting
instructions
on the
heating
section
opera
tion
label
(located
inside
the burner
or blower
access
door)
to
start
the
heating
section.
NOTE:
Make
sure
that
gas supply
has
been
purged,
and
that
all gas
piping
has
been
checked
for leaks.
A. Check
Heating
Control
Start
and
check
the
unit
for proper
heating
control
operation
as follows.
(See
furnace
lighting
instructions
located
inside
burner
or blower
access
panel.)
1. Place
the
room thermostat
SYSTEM
switch
in the
HEAT
position
and
the
fan
switch
in the
AUTO.
position.
2. Set
the
heating
temperature
control
of the
thermostat
above
rooIn
temperature.
3. The
induced-draft
motor
will start.
4. After
a call
for
heating,
the
main
burner
should
light
within
5 seconds.
If the
burners
do not
light,
there
is a
22 second
delay
before
another
5 second
try. If the burn-
ers
still
do not
light,
this
sequence
is repeated.
If the
burners
do not
light
within
15 minutes
from
the
initial
call for heat,
there
is a lockout.
To reset
the control,
break
the
24 v power
to W.
5. The evaporator
fan will turn
on 45 seconds
after
the flame
has
been
established.
The
evaporator
fan
will
turn
off
45 seconds
after
the
thermostat
has
been
satisfied.
B. Check
Gas Input
Check
gas
input
and
manifold
pressure
after
unit
start-up
(see
Table
4). If adjustment
is required
proceed
as follows.
The
rated
gas
inputs
shown
in Table
4 are
for altitudes
from
sea
level
to 2000
ft above
sea
level.
These
inputs
are
based
on natural
gas
with
a heating
value
of 1050
Btu/ft
:_ at 0.65
specific
gravity,
or
propane
gas
with
a
heating
value
of
2500
Btu/ft
:_ at
1.5 specific
gravity.
For
elevations
above
2000 ft, reduce
input
4% for each
1000 ft above
sea level.
When
the
gas
supply
being
used
has
a different
heating
value
or
specific
gravity,
refer
to national
and
local
codes,
or contact
your
distributor
to determine
the
required
orifice
size.
C. Adjust Gas Input
The gas input
to the unit
is determined
by measuring
the
gas flow at the meter
or by measuring
the manifold
pressure.
Measuring
the gas flow at the meter is recommended
for natu-
ral gas units.
The manifold
pressure
must
be measured
to
determine
the input
of propane
gas units.
Measure
Gas Flow (Natural
Gas Units)
Minor
adjustment
to the gas flow can be made
by changing
the manifold
pressure.
The manifold
pressure
must be main
rained
between
3.4 and 3.6 in. wg. If larger
adjustments
are
required,
change
main
burner
orifices
following
the recom
mendations
of national
and local codes.
NOTE:
All other
appliances
that
use the same
meter
must
be turned
off when gas flow is measured
at the meter.
Proceed
as follows:
1. Turn
off gas supply
to unit.
2. Remove
pipe plug on manifold
(see Fig. 19), then
con-
nect manometer
at this point.
Turn on gas to unit.
3. Record number
of seconds
for gas meter test dial to make
one revolution.
4. Divide number
of seconds
in Step 3 into 3600 (number
of seconds
in one hour).
5. Multiply
result
of Step 4 by the number
of cuft
shown
for one revolution
of test dial to obtain
cuft
of gas flow
per hour.
6. Multiply
result
of Step 5 by Btu heating
value
of gas to
obtain total measured
input in Btuh. Compare
this value
with
heating
input
shown in Table 4. Consult
the local
gas supplier
if the heating
value
of gas is not known.
EXAMPLE: Assume
that the size of test dial is 1 cuft,
one
revolution
takes
30 seconds,
and the heating
value
of the gas
is 1050 Btu/ft:L Proceed
as follows:
1. 30 seconds
to complete
one revolution.
2. 3600 + 30 = 120.
3. 120 x 1 = 120 ft :*of gas flow/hr.
4. 120 x 1050 = 126,000 Btuh
input.
If the desired
gas input is 120,000 Btuh,
only a minor change
in the manifold
pressure
is required.
Observe
manifold
pressure
and proceed
as follows to adjust
gas input:
1. Remove covet" screw over regulator
adjustment
screw on
gas valve.
2. Turn
regulator
adjustment
screw clockwise
to increase
gas input,
or turn regulator
adjustment
screw counter
clockwise
to decrease
input.
Manifold
pressure
must
be
between
3.4 and 3.6 in. wg.
3. Replace
cover screw cap on gas valve.
4. Turn
off gas supply
to unit.
Remove
manometer
from
pressure
tap and replace
pipe plug on gas valve.
Turn
on gas to unit and check for leaks.
--17--
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