Page 35
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 your service techni-
cian or gas supplier.
Turning Off Gas to Unit
1 − Set the thermostat to the lowest setting.
2 − Turn off all electrical power to the unit if service is to be
performed.
3 − Remove the upper access panel.
4 − Honeywell VR8205 Gas Valve − Turn knob on gas
valve clockwise
to OFF. Do not force.
5 − Replace the upper access panel.
Gas Pressure Adjustment
Gas Flow (Approximate)
1 − Operate unit at least 15 minutes before checking gas
flow. Determine the time in seconds for one revolu-
tions of gas through the meter.
TABLE 22
Gas Flow Rate (Ft.
3
/Hr.)
Seconds for 1
Revolution
Gas Meter Size
1/2 cu ft Dial 1 cu ft Dial
10 180 360
12 150 300
14 129 257
16 113 225
18 100 200
20 90 180
22 82 164
24 75 150
26 69 138
28 64 129
30 60 120
32 56 113
34 53 106
36 50 100
38 47 95
40 45 90
42 43 86
44 41 82
46 39 78
48 38 75
50 36 72
52 35 69
54 33 67
56 32 64
58 31 62
60 30 60
2 − Compare the number of seconds and the gas meter
size in table 22 to determine the gas flow rate. Multiply
the gas flow rate by the heating value to determine the
unit input rate. If manifold pressure is correct and the
unit input rate is incorrect, check gas orifices for proper
size and restriction.
3 − Remove temporary gas meter if installed.
NOTE − To obtain accurate reading, shut off all other gas
appliances connected to meter.
Manifold Pressure Measurement & Adjustment
NOTE − Pressure test adapter kit (10L34) is available from
Lennox to facilitate manifold pressure measurement.
1 − Connect test gauge to outlet tap on gas valve.
2 − Disconnect pressure sensing hose from barbed fitting
on gas valve. Use an obstruction to plug the hose.
3 − Start unit on low heat 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
23.
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 replace
pressure tap plug.
NOTE − During this test procedure, the unit will be overfir-
ing:
D Operate unit only long enough to obtain accurate read-
ing to prevent overheating heat exchanger.
D Attempts to clock gas meter during this procedure will
be inaccurate. Measure gas flow rate only during nor-
mal unit operation.
7 − When test is complete remove obstruction from hose
and return hose to barbed fitting on gas valve.
Manifold Pressure and High Altitude
Information
The units are factory−ready for use with natural gas. If LP/
propane fuel use is required, a conversion kit must be
installed.
NOTE − A natural to L.P. propane gas changeover kit is nec-
essary to convert this unit. Refer to the changeover kit
installation instruction for the conversion procedure.
Refer to table 23 for proper gas conversion kits and high al-
titude pressure switch kits at varying altitudes. Table 24
lists high fire manifold pressure settings at varying alti-
tudes.
The combustion air pressure switches are factory−set and
require no adjustment.
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