PV 100a
Igniting
In ignition state the igniter is heated up and fan blows hot air through loaded pellets and ignites
them.
Igniter is turned off after every 50 seconds to avoid overheating it, and turned on again after 20s .
Preburn
The purpose of preburn state is to fully ignite the pellets. No fuel is added at preburn. Fan works at
the same speed as in ignition.
Burning
The running position of the burner. Fuel is periodically added and fan is keeping speed according to
air table. Burning state lasts until boiler thermostat is switched off.
Auger control
External auger is holding permanent fuel level in the feeder tube during Burning state. The auger is
controlled by fuel level sensor in following manner:
•
Auger is started after level sensor does not recognize fuel in burner and internal feeder has
done 2 half-rotations.
•
Auger is stopped when level sensor recognize fuel in burner for more than 1s.
Fuel level detection
Pellet level in vertical feeder tube is detected by fuel level sensor (optical). Fuel is detected when
pellets interrupt optical link between sensor pair.
Burner will enter level detection fault condition in following cases:
1. Fuel loading timeout (no signal for specified period of time)
2. Fuel unloading timeout (signal lasts longer than specified period of time)
Output power levels
Burner has 6 preset output power levels. For every level, program calculates correct fuel amount
depending of fuel calorific value and burner internal feeder productivity. The feeder productivity for
normal, light and heavy pellets can be changed from setup menu (par21, par22, par23). For most
pellets it is 78g per rotation. Calculated amount of fuel is divided into periodic feeding cycles. In
every cycle internal feeder makes half rotation. If the calculated cycle comes to short (less than 11s)
then the cycle length is doubled and fuel is fed with by full rotation of feeder. For every power level
there is different preset fan rotation speed (air table).
29
