Allied A97USMV, Руководство по установке

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506887-01 Page 58 of 78 Issue 1213
Manifold Pressure Measurement
To correctly measure manifold pressure, the differential
pressure between the positive gas manifold and the negative
burner box must be considered. Use pressure test adapter
kit (available as part 10L34) to assist in measurement.
1. Remove the threaded plug from the outlet side of the
gas valve and install a field provided barbed fitting.
Connect test gauge “+” connection to barbed fitting to
measure manifold pressure.
2. Tee into the gas valve regulator vent hose and connect
test gauge “-” connection.
3. Start unit on low heat (40% rate) and allow 5 minutes for
unit to reach steady state.
4. While waiting for the unit to stabilize, notice the flame.
Flame should be stable and should not lift from burner.
Natural gas should burn blue.
5. After allowing unit to stabilize for 5 minutes, record
manifold pressure and compare to value given in Table
24.
6. Repeat steps 3, 4 and 5 on HIGH HEAT.
NOTE: Shut unit off and remove manometer as soon as an
accurate reading has been obtained. Take care to remove
barbed fitting and replace threaded plug.
DO NOT attempt to make adjustments to the gas valve.
CAUTION
9. Replace the access panel.
10. Turn on all electrical power to the unit.
11. Set the thermostat to desired setting.
NOTE: When unit is initially started, steps 1 through 11
may need to be repeated to purge air from gas line.
12. If the Appliance will not operate, follow the instructions
“Turning Off Gas to Unit” and call the gas supplier.
Turning Off Gas to Unit
1. Set the thermostat to the lowest settling.
2. Turn OFF all electrical power to the unit if service is to
be performed.
3. Remove the access panel.
4. Move the gas valve switch to the OFF position.
5. Replace the access panel.
Failure To Operate
If the unit fails to operate, check the following:
1.
Is the thermostat calling for heat?
2. Are access panels securely in place?
3. Is the main disconnect switch closed?
4. Is there a blown fuse?
5. Is the filter dirty or plugged? Dirty or plugged filters will
cause the limit conrol to shut the unit off.
6. Is gas turned on at the meter?
7. Is the manual main shut Off valve open?
8. Is the gas valve turned on?
9. Is the unit ignition system in lock out: If the unit locks
out again, inspect the unit for blockages.
10. Is blower harness connected to ignition control? Furnace
will not operate unless harness is connected.
NOTE: To obtain accurate reading, shut off all other gas
appliances connected to meter.
Supply Pressure Measurement
A threaded plug on the inlet side of the gas valve provides
access to the supply pressure tap. Remove the threaded
plug, install a field provided barbed fitting and connect a
manometer to measure supply pressure. Replace the
threaded plug after measurements have been taken.
Gas Pressure Measurement
Gas Flow (Approximate)
Furnace should operate at least 5 minutes before checking
gas flow. Determine time in seconds for
two revolutions of
gas through the meter. (Two revolutions assures a more
accurate time.)
Divide by two and compare to time in Table
21. If manifold pressure matches Table 24 and rate is
incorrect, check gas orifices for proper size and restriction.
Remove temporary gas meter if installed.
Table 21
NOTE: A natural to LP/propane gas changeover kit is
necessary to convert this unit. Refer to the changeover kit
installation instruction for the conversion procedure.
Operating Pressure Signal
Operating pressure signal can be taken while the manifold
pressure pressure check is taken (using two measuring
devices). Or, taken after the manifold pressure measurem -
ent is complete.
1 - Tee into the negative line between the gas valve and
pressure switch and connect to measuring device
negative “-”.
2 - Tee into the positive line between the gas valve and
pressure switch and connect to measuring device
positive “+”..
3 -Start unit on low heat (40% rate) and allow 5 minutes
for unit to reach steady state.
4 -After allowing unit to stabilize for 5 minutes, record
operating pressure signal and compare to value given
in table 25.
5 - Repeat steps 3 on 4 high heat.