Rotex GSU 320, Operating Instructions Manual

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2 x Product description
12 BA ROTEX GSU - 09/2007
Burner setting and power limiting
The gas burner is factory-set to a gas type, which is indicated on the yellow sticker on the fan housing of the burner. The burner
can be operated with the following gas types:
– Natural gas E/H
– Natural gas LL/L
– Liquefied petroleum gas.
Only the heating engineer can change the gas type because this requires resetting the gas burner.
The heating engineer can limit the burner output by entering parameters in the boiler control panel.
– The limiting of the maximum burner output would be advisable, for example, in the event of better supply charges for lower
installed outputs.
– The limiting of the minimum burner output would be advisable, for example, if the flue gas resistance is relatively high and
the flame becomes unstable on minimum load or if the requirements for the partial load are not fulfilled when making the
calculations for the flue gas system.
Controlling the burner output
The controls ROTEX ALPHA 23R and ROTEX THETA 23R determine the requisite flow temperature (corresponding to the set
operating parameters) continuously and feed them to the CVBC automatic firing units of the gas burner. The CVBC automatic
firing unit calculates the necessary burner output from the target value and the values of the flow and return flow temperature
sensors. The determined output is transmitted to the burner fan as a PWM signal. The burner fan immediately adjusts the fan
speed and thus also the combustion air flow. The gas controller controls the gas volume accordingly.
Gas/air compound control
The gas/air compound control (pneumatic compound) ensures that the CO
2
flow is maintained at a suitable level for every output
and is set by the adjusting screw for the gas/air mix (Fig 2-6, item 11) and by the adjusting screw of the gas pressure controller
(Fig 2-6, item 12) if required. The burner immediately responds to every change in the air flow volume through the gas/air
compound control with a corresponding change in the gas flow volume.
The gas/air compound control (pneumatic compound) consists of a Venturi nozzle with a ring-shaped gas inlet and a gas pressure
controller.
A vacuum forms in the centre of the Venturi nozzle depending on the volume flow of the combustible air. This causes the gas to
be drawn into the centre of the Venturi nozzle, conveyed through the burner fan to the burner surface and optimally mixed.
The gas valve can be adjusted for supply pressures from 5 to 60 mbar (zero pressure controller).