Rotex GasSolarUnit Series User Manual

Burner output
The digital ROTEX THETA 23R control unit
integrated into the control panel constantly
determines the required flow temperature
according to the selected operating parame-
ters and passes that value to the gas burner
control unit CVBC. The CVBC calculates the
required burner output from the set value and
the actual flow and return temperatures. This
determined output is converted into a PWM
signal that can be understood by the burner
fan and passed to the fan.
The burner fan responds by immediately
matching the fan speed and therefore the
combustion air flow rate to the demand.
The gas controller regulates the gas volume
accordingly (pneumatic interconnection) to
maintain the correct air excess (air factor l)
over the entire output range.
Gas:air mixture control
The gas:air mixture (pneumatic
interconnection) of the GSU/GCU comprises of
a Venturi nozzle with annular gas inlet and a
gas pressure governor.
It is the task of the gas:air mixture control to
maintain the CO2 progression at any output in
accordance with the selection made at the
gas:air mixture adjusting screw (pos 11) and at
the gas pressure screw (pos 12).
The gas valve can be adjusted for supply
pressure between 5 and 60 mbar (zero
governor).
A negative pressure results in the centre of the
Venturi nozzle that is subject to the
combustion air flow rate. This draws the gas,
that is available at almost without pressure
downstream of the gas:air mixture controller
(zero governor), into the centre of the Venturi
nozzle. That transports it through the burner
fan to the burner surface, ensuring an optimum
mixture. This coupled control enables the
burner to respond immediately to every
fluctuation of the air flow rate by a
corresponding change of the gas flow rate.
Checking the burner adjustment
Warning: Risk of explosions
Incorrect handling of gas
equipment can lead to gas
explosions: Danger to life Only authorised
gas fitters are allowed to work on gas
equipment.
Check the gas type selected at the factory.
After the system has successfully passed its
test run, check the burner output during
emissions test operation at maximum (full
load) and minimum (standard load) burner
output using a flue gas analyser (for emissions
test operation, see chapter 8). Adjust the
burner if the actual carbon dioxide
concentration deviates by more than ± 0.2 %
for the specification. The set carbon dioxide
content (CO
2
) is shown in table 5.1.2, Fig. 5.1.7
and Fig. 5.1.8.
Important: The emissions test
key (see chapter 8) allows the
simple selection of the “Full
load” (parameter 02) and the “Standard
load” (parameter 04) programmed at the
burner control unit parameter level to be
selected.
These settings can be matched to the
individual system requirements by the
heating contractor. Modified settings
should be entered below the type plate on
the settings label.
Consider the selected output limits when
checking the burner settings. Tab. 5.1.2
contains details of the permissible setting
limits and the ROTEX factory settings.
For individually modified output limits,
determine the standard setting values
from Fig. 8.4 and Fig. 5.1.7 or 5.1.8.
[ 36 ]
Construction
The linear gas burner modulating between
5 and 25 kW (GSU 25/GCU 25) or between
8 and 35 kW (GSU 35/GCU 35) of the ROTEX
GasSolarUnit/GasCompactUnit is
characterised by a very quiet operation, the
absence of wearing parts and clean
combustion. The burner is of modular design.
It comprises of the following:
- Burner surface (pos. 1)
- DC fan without collector (pos. 2)
- Venturi mixer nozzle (pos. 8)
- Safety gas governor (pos. 3) with
integral gas filter and solenoid valves
- Burner control unit with integral ignition
and high limit safety cut-out
function (pos. 6)
- Burner flange (pos. 13)
- Ignition electrode block (pos. 15)
- Ionisation electrode (pos. 14)
Resetting the burner
A fault shutdown of the burner is - just like any
other interlocking fault recognised by the
burner control unit - displayed as a
fault code on the boiler control panel display:
“E” and a two digit fault code are displayed.
Briefly press the manual key (pos. 13 in Fig.
4.1.1) resets the burner.

Rotex GasSolarUnit Series Specifications

General

Brand	Rotex
Model	GasSolarUnit Series
Category	Boiler
Language	English