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0006080895 ed 2007/02
TWO-STAGE GAS BURNERS
Lock out and reset
The unit can be reset or brought into lock out mode in two different ways:
Internal
In the lock out case the unit can be reset by pushing the built in button meaning a new start-up cycle is
performed.
External
Instead of using the built-in lock out button the same function can be achieved by using an external button which
connects terminal 9 with A (see also circuit and block diagram).
If the pushputton (internal or external) is pressed during normal operation or during the start sequence for more
then 3 sec. and afterwards released, the control box will perform a shutdown.
NOTE: The unit can only be brought to lockout mode or be reseted if power is applied to the unit.
Function control
For safety reasons the fl ame detection system should be tested on commissioning the installation as well as after
a service or longer shut-down.
a) Start-up with closed gas valve
- After lock out safety time is over the unit has to go into lock out mode!
b) Normal start-up, when burner is running, close gas valve
- After loss of fl ame, the control box has to go into lockout mode
c) Normal start-up, during pre-purge or operation, interrupt the air proving switch
– The control box has to perform a lockout immediatly
d) Bridged air proving switch before start
– the fan motor switches on for approx. 2 - 3 secs, followed by a lockout. After 10 secs., this quick
lockout is resetted by the control box and a second start attempt follows (fan motor switches on for
approx. 2 - 3 secs.). A standard lockout appears if the air proving switch (LW) contact is still in it’s
closed position (e.g. welded contacts). Has the air proving switch (LW) changed to it’s open position in
the meantime (e.g. by a run down motor), a normal start sequence follows.
