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SM FP_Australia 2017/04 EN
Pict.20 – Pressure measuring points
4.4
Fan
The control unit monitories the primary air flow to the burner by varying the fan motor power supply voltage
(DC), ensuring a correct variable speed during the operation according to the output needed.
The fan motor provides an additional control signal to enable/disable operation and the speed of the fan is
measured by the feedback signal provided by the fan’s motor. The signal consists on a square wave with a
frequency proportional to the speed of the fan.
Pict. 21 – Different fan flanges (12 on left and 16 / 20 / 26 l/min models on right)
4.5
Gas Valve
Over the control unit it is possible to control the gas flow to the burner by the modulating gas valve (MV1).
The gas valve is composed by other three solenoids identified as safety valves (SV1 + SV2 + SV3) releasing
the modulated gas to and from the solenoid gas valve.
Gas Pressure
Measurement point
=
P
burner
Air Pressure
Measurement point
=
P
box