Page 24
Orice
@
www.davenet.com for correct sizing information.
NOTE-Do not use thread sealing compound on the or-
BURNER BOX ASSEMBLY
Gas Valve
Burners
Gas Manifold
Rollout Switch
FIGURE 11
4-Primary High Temperature Limit S10
S10 is a SPST N.C. high temperature primary limit for gas
heat and is located on the blower deck to the left of the
blower housing.
N.C. contacts open to de-energize the ignition control
when excessive temperature is reached in the blower
compartment. If the limit trips the blower will be energized.
for limits S10. Limit settings are factory set and cannot be
adjusted. If limit must be replaced, the same type and set
point must be used.
5-Flame Roll-out Limit Switch S47
Flame roll-out limit switch S47 is a SPST N.C. high tem-
perature limit located just above the burner air intake
roll-out (indicating a blockage in the combustion air pas-
immediately closes the gas valve.
Limit S47 is factory preset to open at 290F +
+
out limits are manual reset.
6-Combustion Air Prove Switch S18
Prove switch S18 is a SPST N.O. switch located to the
right of the induced draft assembly. S18 monitors com-
bustion air inducer operation. Switch S18 is wired to the
-
sure fall. This negative pressure fall and switch actuation
allows the ignition sequence to continue (proves, by clos-
ing, that the combustion air inducer is operating before
switch is factory set and not adjustable. The switch will
automatically open on a pressure rise (less negative pres-
.
TABLE 2
S18 Prove Switch Settings
++ 0.10 ++
7-Combustion Air Inducer B6
The combustion air inducer provides fresh air to the burn-
er while clearing the combustion chamber of exhaust gas-
K13 relay..
The inducer uses a 208/230V single-phase PSC motor
All motors operate at 3200RPM and are equipped with
auto-reset overload protection. Inducers are supplied by
various manufacturers. Ratings may vary by manufactur-
unit rating plate.
-
the combustion air inducer to vent exhaust gases from the
burners.
When the combustion air inducer is purging the exhaust
gases, the combustion air prove switch closes, proving
that the combustion air inducer is operating before allow-
ing the ignition sequence to continue. When the combus-
tion air prove switch is closed and the delay is over, the
end of the eight second trial for ignition. All combustion
air inducer motors are sealed and cannot be oiled. The
inducer cannot be adjusted but can be disassembled for
cleaning.
8-Combustion Air Motor Capacitor C3
The combustion air inducer motors in all LDT units require
run capacitors. Capacitor C3 is connected to combustion
air inducer B6. Ratings will be on side of capacitor or com-
bustion air motor nameplate.
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