Ignition Control Led; High Altitude Adjustments; Gas Flow; Gas Pressure Adjustments - Lennox LS25 Series Installation Instructions Manual

Separated combustion unit heater
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Ignition Control LED

The ignition control contains a green LED which indicates
the following:
TABLE 6
IGNITION CONTROL LED
LED
Slow Flash*
Normal Operation - No call for heat
Fast F;lash
Normal Operation - Call for heat
2 Flashes
System lockout - failed to detect or sustain flame
Pressure switch failed closed before CAI
3 Flashes
is energized or failed open after CAI is
4 Flashes
High limit (S10) switch open
5 Flashes
Flame sensed and gas valve (GV1) not energized
6 Flashes
On-board microprocessor fault.
7 Flashes
Pressure switch (S18) closed with inducer off.
8 Flashes
Rollout switch (S47/S195) open. Cycle-power to reset.
Steady On
Steady Off
Internal control board (A3) failure or not power.

High Altitude Adjustments

In Canada, certification for installation at altitudes over
4500 feet (1372m) above sea level is the jurisdiction of
local authorities. Lennox recommends derating 4%/1000
feet above 4,500 feet. Refer to table 7 for natural gas
manifold pressures and the Engineering Handbook for
high altitude kit part numbers.
Units may be fired at full input up to 2000 feet. (610m)
above sea level. Above 2000 feet (610m), manifold pres-
sure must be adjusted. Adjust pressure regulator to pres-
sure shown in table 7.
TABLE 7
CANADA - NATURAL GAS MANIFOLD PRESSURES
[inch w.g. (kPa)]
Altitude in Feet (Meters)
2001-
Unit
0-2000
4500
(0- 610)
(610-
1372)
125, 150,
3.5
3.1
175, 200
(0.87)
(0.77)
250, 300,
3.7
3.2
350, 400
(0.92)
(0.80)
3.7*
3.3*
250, 300,
(0.92)
(0.82)
350
400
* High Fire
**Low Fire
NOTE - A natural to LP/propane gas changeover kit is
required to convert the unit in the field. Refer to the in-
stallation instructions supplied with the changeover kit for
conversion procedure.
UNIT OPERATION
energized
Control board (A3) failure
4501-
5501-
6501-
5500
6500
7500
(1372-
(1677-
(2012-
1676)
2012)
2286)
2.8
2.6
See Kit Instruction
(0.70)
(0.65)
2.9
2.8
2.6
(0.72)
(0.70)
(0.65)
2.9*
2.8*
2.6*
(0.72)
(0.70)
(0.65)
1.6** (0.40)
1.7**(0.42)
In the US, units may be fired at full input up to 2000 feet
(610m) above sea level. Above 2000 feet (610m), unit
must be de-rated by four percent per 1000 feet for in-
stallation above 2000 feet. The de-rate may be accom-
plished by adjusting the manifold pressure. Refer to table
8 for natural gas manifold pressures and the Engineering
Handbook for high altitude kit part numbers.
US - NATURAL GAS MANIFOLD PRESSURES
Unit
125, 150,
175, 200
250, 300,
350, 400
250, 300,
350
400
* High Fire
In some cases, it is necessary to change the pressure
switch to ensure proper operation at higher altitudes. See
EHB for high altitude pressure switch kits.
The combustion air inducer proving switch is factory set.
No adjustment is necessary.

Gas Flow

To check for proper gas flow to the combustion chamber,
determine the Btu input from the appliance rating plate. Di-
vide this input rating by the Btu per cubic feet of available
gas. Result is the required number of cubic feet per hour.
Determine the flow of gas through the gas meter for two
minutes and multiply by 30 to get the hourly flow of gas.
Supply Gas Pressure Adjustment
Supply pressure should be checked with unit firing at max-
imum rate. For Natural Gas, supply pressure should be
7501-
maintained in accordance with the specified minimum and
9500
maximum supply pressures on the unit rating plate.
(2286-
2896)
A natural gas to LP/propane gas changeover kit is re-
quired to convert the unit in the field. Refer to installation
instructions provided with changeover kit for conversion
procedure along with propane minimum and maximum
See Kit
supply pressures.
Instruction
See Kit
Supply Pressure Measurement
Instruction
1 - Shut off the manual main supply valve (field
furnished) when installing or removing the measuring
device (Steps 2 and 6).
2 – Connect the measuring device based upon type of
gas valve.
For White Rodgers 36G valve (Figure 13), an inlet post lo-
cated on the gas valve provides access to the supply pres-
sure. Open the inlet port by backing out the 3/32" hex screw
one turn. Connect a piece of tubing over the inlet post and
route to a measuring device to measure supply pressure.
Page 22
TABLE 8
[inch w.g. (kPa)]
Altitude in Feet (Meters)
0-2000
2001-3000
3001-4000
(0- 610)
(610- 914)
(915- 1219
3.5
2.9
2.7
(0.87)
(0.72)
(0.67)
3.7
3.1
2.8
(0.92)
(0.77)
(0.70)
3.7*
3.1*
2.8*
(0.92)
(0.77)
(0.70)
1.6** (0.40)
1.7** (0.42)
**Low Fire
4001-5000
5001-10000
(1220-1524)
(1524-3048)
See Kit Instruction
2.6
See Kit
(0.65)
Instruction
2.6*
See Kit
(0.65)
Instruction

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