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Post-Start Checklist
After the entire control circuit has been energized and the
heating section is operating, make the following checks:
1.
Check for gas leaks, using soapy solution, in the unit
piping as well as the supply piping.
2.
Check the supply gas pressure. It must be within the
limits shown on the rating plate. Supply pressure
should be checked with all gas appliances in the
building at full fire. At no time should the standby gas
pressure exceed 13" w.c., nor the operation pressure
drop below 5" w.c. for natural gas units. If gas pressure
is outside these limits, contact the gas supplier for
corrective action.
3.
Select indoor blower speed tap, which provides a
temperature rise within the range specified on the
rating plate.
4.
Verify manifold gas pressure
NOTE: For purpose of this measurement, the minimum
permissible gas supply pressure is 5" w.c. for natural
gas.
a.
Slide the gas valve switch to the "OFF" position
(see Figure 7).
b.
Remove plug on valve marked "OUTLET
PRESSURE."
c.
Install a water manometer.
d.
Slide the gas valve switch to the "ON" position
and initiate a call for heat. During steady state
operation, manifold pressure should be:
Manifold Pressure
(non-adjustable)
e.
After verifying pressure, turn gas off, remove
manometer fitting, and replace pipe plug and
regulator cap.
f.
Put furnace in operation and check plug for leaks
using soapy solution.
5.
Check the furnace input rate by observing the gas
meter, making sure all other gas appliances are turned
off. The test hand on the meter should be timed for
at least one revolution, noting the number of seconds
per revolution. The heating value of the gas can be
obtained from the local utility.
NOTE: Gas input must never exceed the input capacity
shown on the rating plate. The furnace is equipped
for natural gas rated inputs with manifold pressure
of 2.7 - 3.1" w.c.
Cubic Feet per
Revolution
BTU/HR
=
Input
# Seconds per
Revolution
2.7 - 3.1" w.c.
Heating
x
3600
x
Value
Page 14
For example, by actual measurement, it takes 67 seconds
for the hand on the 1-cubic foot dial to make a revolution
with a 54,000 BTU/HR furnace running. The result is 53,731
BTU/HR (based on a heating value of 1,000 Btu/ft³), which
is close to the 54,000 BTU/HR rating of the furnace.
High Altitude
The input rate shown on the rating plate is for elevations up
to 2000 feet. Units are not certified for installations above
4500 feet.
Heat Anticipator
The heat anticipator setting is 0.75 amp. It is important
that the anticipator setpoint be correct. Too high of a setting
will result in longer heat cycles and a greater temperature
swing in the conditioned space. Reducing the value below
the correct setpoint will give shorter "ON" cycles and
may result in the lowering of the temperature within the
conditioned space.
Operation
Cooling System
The cooling system is factory-charged with HFC-R-410A.
The compressor is hermetically sealed and base-mounted
with rubber-insulated bolts.
Cooling Sequence of Operation
When the thermostat calls for cooling, R is closed to Y (see
the wiring diagrams). This action completes the low voltage
control circuit, energizing the compressor, condenser fan
motor, and blower motor.
Unit compressors have internal protection. In the event there
is an abnormal rise in the temperature of the compressor,
the protector will open and cause the compressor to stop.
A combustion air inducer operates for the first 10 seconds
of every cooling cycle to prevent insects from nesting in
the flue outlet.
Blower Delay – Cooling
The circulating air blower is controlled by a timing circuit
in the integrated blower/ignition control. Timings are not
adjustable. Blower "ON" delay is 5 seconds after the
compressor starts and blower "OFF" timing is 60 seconds
after the compressor shuts down.
NOTE: There is no blower OFF delay when there is a call
for G (fan only).
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