Electric Heat Start-Up; Optional Supply Air Vfd - Lennox LCH036 Installation Instructions Manual

2- Combustion air pressure switch proves inducer
operation. After a 30-second pre-purge, power is
allowed to ignition control. Switch is factory set and
requires no adjustment.
3- Spark ignitor energizes and gas valve solenoid
opens.
4- Spark ignites gas, ignition sensor proves the flame
and combustion continues.
5- If flame is not detected after first ignition trial, ignition
control will repeat steps 3 and 4 two more times
before locking out the gas valve.
6- For troubleshooting purposes, an ignition attempt
after lock out may be re-established manually. Move
thermostat to "OFF" and return thermostat switch to
"HEAT" position.
B-Limit Controls
Limit controls are factory-set and are not adjustable. Two
limits are located on the drip shield in the blower
compartment. See figure 24.
LIMIT LOCATION
DRIP
SHIELD
LIMITS
FIGURE 24
C-Heating Adjustment
Main burners are factory-set and do not require adjustment.
Gas manifold pressures should match pressures shown
in table 10.
TABLE 10
Natural Gas
1st Stage 2nd Stage
+ 0.2 + 0.3
1.6 3.7
Propane (LP) Gas
1st Stage 2nd Stage
+ 0.2 + 0.3
5.5 10.5
Page 33
Electric Heat Start-Up (LCH Units)
Factory- or Field-Installed Option
Electric heat will stage on and cycle with thermostat
demand. Number of stages of electric heat will vary
depending on electric heat assembly. See electric heat
wiring diagram on unit for sequence of operation.

Optional Supply Air VFD

Units may contain a supply air blower equipped with a
variable frequency drive A96 (VFD) which varies supply
air CFM.
The supply air VFD (A96) is located near the
compressors. See figure 25.
A-Start-Up
1- A pressure transducer (A30) is shipped in a box in the
blower compartment.
according to manufacturer's instructions.
Note - Make sure the transducer is installed in the main
duct at least 2/3 of the distance away from the unit.
SUPPLY AIR VARIABLE FREQUENCY DRIVE
CONTROLLER
TB24
TB18
FIGURE 25
Install the transducer
A55 UNIT
A96 SUPPLY
AIR VFD