Lennox KGA Series Service Literature page 20

D-GAS HEAT COMPONENTS
KGA092/150 units are available in 130,000 BTUH (38.1
kW), 180,000 BTUH (52.7 Kw) or 240,000 BTUH (70.3
kW) heat sizes.
1-Heat Exchanger Figure 10
The KGA units use aluminized steel inshot burners with
tubular aluminized steel heat exchangers and two‐stage
redundant gas valves. KGA092/150 units use one eleven-
tube/burner for high heat, one eight-tube/burner for me­
dium heat and one six-tube/burner for standard heat. Burn­
ers in all units use a burner venturi to mix gas and air for
proper combustion. Combustion takes place at each tube
entrance. As hot combustion gases are drawn upward
through each tube by the combustion air inducer, exhaust
gases are drawn out the top and fresh air/gas mixture is
drawn in at the bottom. Heat is transferred to the air stream
from all surfaces of the heat exchanger tubes. The supply
air blower forces air across the tubes to extract the heat of
combustion. The shape of the tubes ensures maximum
heat exchange.
The gas valves accomplish staging by allowing more or less
gas to the burners as called for by heating demand.
HEAT EXCHANGER ASSEMBLY
HEAT
EXCHANGER
TUBE
COMBUSTION
AIR INDUCER
GAS VALVE
BURNER
FIGURE 10
2-Burner Box Assembly (Figure 11)
The burner assembly consists of a spark electrode, flame
sensing electrode and gas valve. Ignition board A3 controls all
functions of the assembly.
Burners
All units use inshot burners. Burners are factory-set and do
not require adjustment. A peep hole with a cover is fur­
nished in the heating access panel for viewing the
burner flame. Always operate the unit with the ac­
cess panel in place.
Burners can be removed individually for service.
Burner maintenance and service is detailed in the
SERVICE CHECKS section of this manual.
3-Primary High Temperature Limit S10
S10 is a SPST N.C. high-temperature primary limit for gas
VENT
CONNECTOR heat in KGA092/150 units. On KGA092/150 units, S10 is lo­
cated next to the blower. See figure 12.
Page 20
Orifice
Each burner uses an orifice which is matched to the burn­
er input. The orifice is threaded into the burner manifold.
The burner is supported by the orifice and will easily slide
off for service once the mounting screws are removed from
the burners.
NOTE-Do not use thread sealing compound on the
orifices. Using thread sealing compound may plug
the orifices.
Each orifice and burner are sized specifically to the unit.
Refer to Lennox Repair Parts Listing for correct sizing infor­
mation.
BURNER BOX ASSEMBLY
GAS
VALVE
FLAME ROLLOUT LIMIT SWITCH
BURNERS
IGNITOR
(not shown)
GAS MANIFOLD
FIGURE 11
FIGURE 12
FLAME
SENSOR
S10 LIMIT LOCATION