Nu-Way MGN 2800N Installation & Maintenance Manual

Nu-Way MGN 2800N Installation & Maintenance Manual Manual pdf 20 page image

MGN 2800N HP 19With the burner now running on high flame, the gas throughputs should be checked at the gas meter.Ensure that any other appliances served by the meter are isolated during the checks. The gas ratecan be altered by adjusting the air damper opening in the appropriate direction. Similarly the lowflame throughput can be adjusted by altering the low flame position of the air damper. Care shouldbe taken so as not to exceed the limits of the burner performance envelope as shown on page 26.With the gas flow rate set for both Low & High flame a final check should be made on the flue gases.For reasons of safety, the CO (carbon monoxide) level should be checked and should not exceed amaximum of 93 ppm (dry air free).BURNER START GAS RATESwitch off the electrical supply to the burner, close the main manual gas valve, remove the controlpanel cover, disconnect the pilot check link, and replace the control panel cover.Switch on the electrical supply to the burner and allow the burner to establish start rate flame.The start gas rate can now be adjusted by turning the adjusting screw in the start gas pressuregovernor clockwise to increase and anticlockwise to decrease. A start rate of approximately 30% andnot more than a maximum of 33% of main flame is required.Too small a start gas rate results in burner lockout on changeover during the initial and final running.Never exceed the stated percentage start gas rate.Switch off the electrical supply, remove the control panel cover. Open the main manual gas valve.Switch on the electrical supply to the burner.Check Flame SignalSwitch off the burner. Remove the control panel cover and disconnect the flame signal check link.Connect a DC microammeterRefer only to the wiring diagram appropriate to the control fitted on the burnerSwitch on the burner and observe on the microammeter the flame response signal. A steady readingin excess of 75μA indicates the burner is in a reliable run situation.If the current recorded is too low, it may be due to some maladjustment of the flame and intermittentlockout may occur. Check and reset if necessary. Refer to the Fault Finding section. Switch off theburner and disconnect the microammeter. Refit the link and control panel cover.Air Pressure Switch SettingSwitch off the electrical supply to the burner.Remove the air pressure switch cover. Fit a manometer to the pressure switch to check the actual airpressure against the pressure switch dial setting.Remove the control panel cover and disconnect the low flame hold link to hold the burner in the lowflame position.Switch on the electrical supply and allow the burners to establish the main flame.Slowly turn the adjusting dial clockwise until the flame is extinguished. The burner will go to lockout.Turn the dial one division anticlockwise and reset burner lockout. The burner will then continuethrough its cycle until either the start rate flame is established or the burner goes to its lockoutposition. If the burner goes to lockout repeat the procedure once per burner cycle until the start rateflame is established. Allow the burner to cycle to low flame and then turn the adjusting dial a furthertwo divisions anticlockwise.Switch off the electrical supply to the burner, reconnect the low flame hold link, replace the controlpanel cover and also the air pressure switch cover, and remove the manometer.