Page No 26 of 52 Reznor, Photon, Installation Manual, EN 2021-04, D301310 Iss 0
C
Operation
The appliance requires a 0-10VDC signal to
control the burner. A value > 1.0VDC will
indicate a heat demand and the combustion fan
will start the pre-purge.
Before an ignition attempt the combustion
fan slows to ignition speed. When the ignition
speed has been reached the burner will attempt
ignition.
If ignition is unsuccessful there will be another
purge followed by ignition. The total number of
ignition attempts before lockout is 3.
The spark electrode stays energised throughout
the ignition attempt, even if the flame has been
established.
Once the flame has been sensed the burner
will run at the ignition speed for a few seconds
to allow the flame to stabilise. Following flame
stabilisation the fan speed will increase to high
fire to allow the heat exchanger to warm up
quickly.
After a short delay the air movement fan will
start. Once warm up has completed the burner
is released to the control of the 0-10VDC
thermostat and will modulate to the requested
heat demand.
The burner will begin to modulate before the
set temperature has been reached. At this point
the burner rate will adjust according to the heat
demand from the thermostat. When set point
temperature is reached the burner will turn off
and the appliance will post-purge to dissipate
any residual heat.
If, for any reason, the burner flame is
extinguished during a run cycle, an automatic
attempt at re-ignition will take place. If after
three ignition attempts the burner does not
relight, safety shut down and lockout will occur.
Manual intervention to reset will be necessary to
put the unit back into service.
In the event of overheating for any reason,
overheat controls operate to switch off the
burner.
In case the heat exchanger’s temperature is
too high, the burner will be switched off by
the LC1 limit control (first safety). The burner
automatically switches on again after cooling
down and re-start will take place.
The limit control LC3, which operates at a higher
temperature setting, switches off the burner to
a lockout condition requiring a thorough check
of the heater and a manual reset via the LC3
limit control body followed by the lockout reset
switch. A cooling time of about 3 minutes is
necessary before resetting.
LC3 reset switch Photon 10-20
LC3 reset switch Photon 25-100
LC3 reset switches Photon120
LC3 reset switch
LC3 reset switch
LC3 reset
switches
