Bulex Thema Condens AS 48-A, Manual, Page: 66 / 199

MAKSİCONDENSE 48-65
Notes
01/2018 60 Training 0020260859_00
Key
1 Flue gas 5 Characteristic line
– Output/target speed
2 Fan motor 6 Primary gas regulation valve
3 Primary gas valve 7 Setting screw:
Characteristic
– Air volume/
gas volume
4 Characteristic
– Air volume/
gas volume
Depending on the unit output required at the time, a rotational speed target value is forwarded to the
fan as a PWM signal. The burner is now always modulated by modifying the air flow (PWM signal)
of the fan.
The gas volume follows the air flow in a predefined ratio through the pneumatic
gas-air mixture, as both variables are linked.
This allows the air ratio to remain almost constant throughout the entire modulation range. To control
the gas valve assembly using the pneumatic gas-air mixture technology, a powerful fan is required
to overcome pressure losses.
It is possible to use the adjusting screw at the outlet of the gas valve assembly (2)
– see the next
figure
– to manually adjust the gas-air flow ratio.