Operation - Modine Manufacturing POR Installation And Service Manual

oPeration

figure 11.1
cutaway through oil-fired unit Heater
16
10
operating sequence
CAUTION
Start-up and adjustment procedures should be performed by
a qualified oil serviceman.
The operation of Modine oil-fired unit heaters is governed by a
primary control which operates the burner, and a fan and limit
switch which controls the circulating air fan dependent on the
heat exchanger temperature.
The primary control is energized when the thermostat "calls" for
heat. It starts the burner motor which turns the combustion air
blower and fuel unit. The fuel unit is a 2-stage type that draws
oil from the supply tank and delivers it at high pressure to the
burner nozzle.
Combustion will be established and the heat exchanger will
begin to warm-up. When the fan and limit switch detects the
proper temperature, it will turn on the circulating air fan. The
time it takes before the circulating air fan turns on after the
burner is started is a function of the temperature setting on the
fan and limit switch.
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2
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12
15
11
9
8
7
1. Combination fan-limit switch
2. Flue outlet
3. Flame inspection port cover
4. Horizontal louvers
5. Clean-out covers
6. Heat exchanger
7. Ceramic fiber fire-pot
8. Flame-retention head
9. Nozzle electrode assembly
10. Junction box
11. Burner motor and assembly
12. Finger-proof fan guard
13. Internal baffle
14. Heater fan
15. Primary control
16. Ignitor
When the thermostat is satisfied, the primary control will shut off
the burner. The circulating air fan will shut off when the fan and
limit switch detects a sufficiently low temperature. The fan and
limit switch also has a manual switch which allows constant "fan
on" operations.
safety devices
Do not reset primary control if heat exchanger is hot. Wait
until cooled. If unit fails to operate properly after resetting
twice, consult the factory.
The primary control is a constant ignition device that allows the
electrodes to spark continuously as the burner runs. It uses the
cad cell to detect the presence of a flame. Upon start-up, if no
flame is detected, the primary control will permit the burner to
run for a maximum of 15 seconds before "lockout". It must be
manually reset before the unit can be started.
4-522.4
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4
5
6
CAUTION
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