Appendix A
Publication No. 559779
38
Appendix A – Page 38
Burner pressure checking and adjustment procedure.
This appliance is fitted with a Gas/Air ratio control mixing
valve. This gas valve ensures that the correct amount of gas
is delivered to the burner to match the available air supply
under all operating conditions. The burner pressure and gas
rate have been precisely set and checked during
manufacture and it is extremely unlikely that any further
adjustment will be necessary.
To check the correct operation of the gas valve follow the
instructions below carefully.
a.
A good indication of correct operation of the boiler will be
obtained by measuring the gas rate at the gas meter.
1.
Run the appliance for at least 10 minutes. Ensure
that the boiler is not modulating by operating in DHW
mode with a hot water tap fully open.
2.
With all other gas appliances turned off measure the
gas rate at the meter for a period of at least 5
minutes. Check that the measured rate is within ±
5% of the rate stated on the data plate.
b.
To measure the burner pressure.
1.
Turn off the gas service cock. Fit a pressure gauge
to the gas inlet pressure test point on the gas control
valve. Connect a differential pressure gauge or 'U'
tube manometer between the burner pressure test
point (high pressure side) and the reference pressure
test point (low pressure side) on the gas valve (See
Fig. 24).
2.
Turn on the gas service cock and run the appliance
for at least 10 minutes. Check that the gas inlet
pressure is between 19-20 mbar.
3.
Check that the differential burner pressure is within ±
1.0 mbar of that stated on the data plate.
4.
Turn off the gas service cock and remove the
pressure gauge and replace the pressure test point
sealing screws on the gas valve.
A burner pressure reading outside the specified range does
not necessarily indicate a wrongly adjusted gas valve. Other
factors i.e. insufficient air flow will cause the gas valve to
automatically adjust the burner pressure to maintain safe
combustion. Before attempting to adjust the gas valve a
check must be conducted on the whole appliance to ensure
that any other faults present are found and rectified.
Setting the Burner Pressure
WARNING
Setting the burner pressures on a modulating gas/air control
valve is a complex procedure and should only be attempted
by a competent person. Incorrect adjustment will impede
the performance of the boiler and may result in
HAZARDOUS COMBUSTION
. Setting the burner pressure
requires the following equipment.
Essential
1.
A differential pressure gauge or 'U' tube manometer
capable of measuring pressures in the range 0-25 mbar
(0-10 'H2O) with a resolution of 0.1 mbar (0.05 'H2O).
2.
A differential pressure gauge capable of measuring
pressures in the range of 0-2.50 mbar (0-1.00 'H2O)
with a resolution of 0.01 mbar (0.005 'H2O).
3.
Sufficient flexible tube and 'T' piece connector to enable
these instruments to be connected to the gas valve in
the arrangement shown in Fig. 24.
4.
A CO2 analyser capable of measuring CO2
concentrations in the range 0 - 15% with a resolution of
0.1%.
Setting Procedure
1.
Remove sealing screws and connect the two differential
pressure gauges to the gas valve as shown in Fig. 24
and remove the adjustment screw sealing cap.
2.
Run the appliance for at least 10 minutes. Ensure that
the boiler is not modulating by operating in DHW mode
with a hot water tap fully open.
3.
Enter the INSTALLER MODE on the control board and
set the MAXIMUM fan speed G to 40. This will force the
fan to run at minimum modulation.
4.
Note the gas valve signal pressure (differential pressure
gauge 2) and burner pressure (differential pressure
gauge 1) Check that both pressures are within the
minimum modulation operating range shown (page 39).
If the burner setting pressure is outside the range reset
to the pressure indicated on the SETTING LINE
corresponding to the measured gas valve signal
pressure. If the gas valve signal is outside the range
contact the Potterton Service Department.
5.
Enter the INSTALLER MODE on the control board and
set the MINIMUM fan speed G to 99. This will force the
fan to run at maximum modulation.
6.
Note the gas valve signal pressure (differential pressure
gauge 2) and burner pressure (differential pressure
gauge 1) Check that both pressures are within the
range shown (page 39). If the pressures are outside
Summary of Contents for Envoy Flowsure
Page 4: ...Technical Data Publication No 559779 4 Technical Data Page 4 Fig 2 ...
Page 13: ...Publication No 55977 Installation 13 Installation Page 13 ...
Page 32: ...Fault Finding Chart Publication No 559779 32 Fault Finding Page 32 ...
Page 33: ...Publication No 55977 Fault Finding Chart 33 Fault Finding Page 33 ...
Page 34: ...Fault Finding Chart Publication No 559779 34 Fault Finding Page 34 ...
Page 36: ...Boiler Wiring Layout Publication No 559779 36 8 Boiler Wiring Layout Page 36 ...
