Appendix C - Motorised High/Low Control; General; Operation - FULTON J Series Installation, Operation And Maintenance Manual

Fulton Ltd
1.1

GENERAL

The Fulton motorised high/low control is designed to improve the efficiency of the boiler by
switching the firing rate from high fire (when there is low steam pressure in the boiler) to low fire
(when the boiler reaches a high steam pressure). The systems major components comprises of;
two stage gas valves, motorised air damper unit and two stage steam pressure switches.
The adjustment of the air gate control motor or the two stage gas valve should only be carried out by
qualified personnel, incorrect adjustment could result in damage to the pressure vessel and/or the
Air Damper Housing
High/Low Fire Cams
Air Damper Motor
1.2

OPERATION

With the steam pressure switch pre-set to the high and low fire operational requirements of the
system, and the boiler operating normally, steam pressure will gradually increase until the high
pressure limit is reached, the pressure switch will then switch the two stage gas valve and the air
damper motor to the low fire position.
The boiler will continue to operate at low fire until the steam pressure falls to the low pressure
limit setting on the pressure switch. At this point, the gas valve and the air damper will switch the
boiler into high fire mode and the sequence of high fire / low fire is regulated automatically with no
routine maintenance required.
Note: Should the boiler attain the off setting of the on/off control pressure switch, the burner will switch off on low
fire and then restart in the normal way on high fire.
JGASUK-IOMM-2015-2
!
IMPORTANT
production of harmful combustion gases.
Figure. 36 - High/Low Control
APPENDIX C - MOTORISED
HIGH/LOW CONTROL
APPENDIX - C
Page 57