INOV8 Model F240 – Edited September 2008
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ADDENDUM
THEORY OF OPERATION
Overview:
When the wall thermostat calls for heat, it does so by sending power to the Fireye
controller, which then turns on the burner motor and oil heater. The burner motor drives
the oil pump which circulates the oil through the module, vapor eliminator and back to the
pump to be circulated again. On each pass through the module, the oil gets a little hotter
by passing close by the oil heater. Each pass through the vapor eliminator filters it and
vents off any vapor that may have been released by heating and the churning action of
the pump. This heating and circulating continues until the oil reaches firing temperature.
At that time a signal is sent to the controller, causing it to start the 90-second pre-purge
timeout and then fire the burner.
The ultraviolet sensor (U.V. sensor) will be watching the flame while the burner is running
and a loss of flame will cause it to shut off for 90 seconds and then try to fire again
(retry). Should the burner fail to ignite (whether on the initial attempt or on a retry), the
U.V. sensor will notice the absence of flame and signal the controller to shut off the
burner on alarm.
Assuming the burner started and is running O.K., it will continue circulating and heating
the oil (under control of a thermostat that maintains it at firing temperature) until the wall
thermostat decides the building is hot enough and turns it off.
In Depth
Sequence of Events:
1. The wall thermostat sends 120v to controller terminals 1 and 7. The voltage on
terminal 7 causes the controller to turn on the OPR CTRL light and close a relay,
which puts 120v onto controller terminal 8.
2. Voltage on terminal 8 is fed to:
a. The burner motor that will now start circulating the oil through the burner.
b. The heater switch which, if ON, will start heating the circulating oil.
c. The Ignition test switch which, if depressed, will turn on the electrodes.
d. The orange boost pump control wire which, if you have an electrically controlled
boost pump, will cause it to start running.
3. At this time the controller also starts looking for flame in the burning chamber. There
should be none, if a continuous flame signal is detected for some reason, the
controller will shut off the burner on alarm without trying to fire.
4. When the module block (oil) reaches the OUT2 set point in the oil temperature
controller, that controller will place 120V on its OUT2 terminal (9) which is tied back
to the Fireye interlock terminal (6). Note: If the heater switch had been OFF, the
120v signal would have been sent back as soon as the burner motor started.
5. The controller, seeing voltage on terminal #6, turns the blinking INTRLCK light on
solid and starts the 90 second pre-purge.
6. At the end of the 90 seconds the controller puts 120v on terminal 4 to turn on the
ignition transformer and terminal 3 to ‘turn on’ the orange wire firing circuit. The next
10-second period is called “Pilot Trial For Ignition” and is represented by the PTFI
light on the controller being on.
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