16. Changing the low fire setting on the air/gas ratio controller will have a slight effect on the high
fire setting. It may therefore be necessary to repeat steps 13 to 15 several times in order to
achieve acceptable levels of CO
2
at both firing rates.
17. With the burner running on high fire, check the gas flow rate with an appropriate instrument,
ensuring that the instrument has been calibrated before use. If the flow rate is to be measured
using the main site gas meter or a supplementary meter ensure that all other gas appliances
served by that meter are isolated.
18. Check the gas flow rate with the burner running on low fire. The appropriate low fire rate is
governed by the low fire combustion air setting achieved during the oil commissioning phase.
The turndown between high and low fire should therefore mirror the figure achieved during this
phase. If oil is unavailable and the burner is commissioned for gas firing only, then the gas rate
can be adjusted by varying the low and high fire positions of the air damper. In this case care
should be taken not to exceed the limits of the burner performance envelope shown in the
Appendix.
19. Analyse the flue products on both high and low fire.
Setting the Start Gas Rate
** Warning:
Extended firing on start gas rate only can lead to a build-up of volatile gases within the
appliance combustion chamber. Running should be kept to maximum of 5 MINUTES ONLY.
1.
Switch off the burner and the electrical power supply to the burner.
2.
Remove the control panel cover and remove the pilot check link. Replace the cover.
3.
Establish the electrical supply to the burner and switch on the burner. Allow the burner to light
and establish the start gas flame.
4.
Check the gas flow rate. The appropriate setting is usually found between 25 and 30% of the
main flame gas rate. The start gas rate must never be set at a higher level than 33%.
5.
If it is necessary to adjust the start gas rate, turn the adjusting screw in the start gas pressure
governor clockwise to increase the gas rate and anti-clockwise to reduce it. Make small
adjustments and check the gas rate after each change.
6.
Switch off the burner and electrical power supply to the burner. Remove the control panel cover
and replace the pilot check link. Replace the cover.
Setting the High Gas Pressure Switch
1.
Remove the cover from the high gas pressure switch.
2.
Establish the electrical supply to the burner and switch on the burner. Allow the burner to
proceed through its operating sequence until it is operating on high fire.
3.
Turn the adjusting dial on the pressure switch anti-clockwise slowly until the switch trips. The
pressure switch indicating light will be illuminated at the completion of the shutdown cycle.
4.
Turn the adjusting dial approximately 20% clockwise.
5.
Refit the cover and reset the pressure switch by pressing the button on the cover. The burner
will restart.
Setting the Low Gas Pressure Switch
1.
Switch off the burner and the electrical power supply to the burner.
2.
Remove the cover from the low gas pressure switch.
3.
Establish the electrical supply to the burner and switch on the burner. Allow the burner to
proceed through its operating sequence until it is operating on high fire.
4.
Turn the adjusting dial on the pressure switch clockwise one small step at a time until the switch
trips, causing the burner to shut down. Turn the adjusting dial anti-clockwise until main flame
can be established.
MDFL 3300 & MDFL 4000 Issue 2 08/08
Page 33
Summary of Contents for MDFL 3300
Page 16: ...MDFL 3300 MDFL 4000 Issue 2 08 08 Page 15 VALVE PROVING SYSTEM LDU 11 Standard fitting...
Page 30: ...MDFL 3300 MDFL 4000 Issue 2 08 08 Page 29 MODULATING CAM BOX...
Page 43: ...Electrode Setting Details MDFL 3300 MDFL 4000 Issue 2 08 08 Page 42 All dimensions in mm...
Page 48: ...NOTES MDFL 3300 MDFL 4000 Issue 2 08 08 Page 47...