3 Commissioning Procedure
Mk8 MM Manual Page | 84
message ‘Select Commissioning’ will appear. Press and the MM will go through purge. The
message ‘Set up START position’ will appear to ignite a flame in the burner, see section 3.4.4. Once the
burner is firing, the message ‘Set FGR Position’ will appear. Press to enter the FGR START
position. The message ‘Save Commission’ will appear, press to save the FGR START position
and then press to return to run mode.
Note: If both Golden Start and FGR are optioned then the GOLDEN START position is entered before the
FGR START position.
Flue Gas Recirculation (FGR) is a method whereby a quantity (approximately 15%) of the boiler flue gases
are fed back to the burner and mixed with the combustion air. The virtue of FGR is the reduction of NOx
gases. With the FGR facility, servomotor channel 3 can be used to control the amount of flue gas fed back. It
is not good practice to feed back the gases when the flue gas is cold, so all the elements (i.e. servomotors
and VSD) can be set at ‘FGR’ positions until the gases are hot. During this time the CH3 would normally be
set closed. Once the FGR holding conditions are met, modulation takes place in the normal way using the
curve entered during commissioning.
FGR can be set as a Timer, Offset or Temperature Threshold (see options 48, 49 and 50).
Note: Golden start takes priority over FGR. Once the golden start timer has finished, the servomotors will go
straight to the FGR start position.
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