Unigas R91, Installation Manual

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PART III: OPERATION
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sting pressure) until the burner lockout, then read the value on the pressure switch scale and set it to a value reduced by 15%.
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Repeat the ignition cycle of the burner and check it runs properly.
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Refit the transparent plastic cover on the pressure switch.
4.13 PGCP Gas leakage pressure switch (witn Siemens LDU/LME7x burner control/Siemens LMV Bur-
ner Management System)
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remove the pressure switch plastic cover;
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adjust the PGCP pressure switch to the same value set for the minimum gas pressure switch;
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replace the plastic cover.
4.14 Adjusting the combustion head
Only if necessary, change the combusiton head position: to let the burner operate at a lower output, loose the VB screw and move pro-
gressively back the combustion head towards the MIN position, by turning clockwise the VRT ring nut. Fasten VB screw when the
adjustment is accomplished.
4.15 Center head holes gas flow regulation (R525)
To adjust the gas flow, partially close the holes, as follows:
1
loosen the three V screws that fix the adjusting plate D ;
2 insert a screwdriver on the adjusting plate notches and let it move CW/CCW as to open/close the holes;
3 once the adjustmet is performed, fasten the V screws.
The adjusting plate correct position must be regulated in the plant during the commissioning.
Attention! if it is necessary to change the head position, repeat the air and fuel adjustments described above.
CAUTION: perform these adjustments once the burner is turned off and cooled.
VRT
VB
V
D
closed holes
opened holes