Set Appliance State:
Gas On; Pilot On
CH Demand
Isolate Mains Power to appliance as per TOPs P4
Selector switch in CH CONTINUOUS position
Attach U-gauge to burner pressure test point
CH Potentiometer to maximum
Selector switch in CH CONTINUOUS position
Attach U-gauge to burner pressure test point
CH Potentiometer to maximum
| WARNING! - Mains voltage is expected during test follow TOPs P4 live testing procedure |
Measurement:
Allow burner to ignite and allow CH system to heat to a reasonable temperature.
Turn down the CH potentiometer.
Does the burner pressure reduce from its set pressure to approximately 2.5 mb as the temperature demand is met?
Notes: If the boiler has been set at its lowest output then modulation will not take place. To reduce the time taken for this test, it may be necessary to reduce the heating load by turning off some radiators.
If power has been switched off or CH demand has been interrupted, there will be a delay of between 1 and 3 minutes before the boiler starts.
When U-gauge is removed, test point should be tightened and checked for gas soundness.
Turn down the CH potentiometer.
Does the burner pressure reduce from its set pressure to approximately 2.5 mb as the temperature demand is met?
Notes: If the boiler has been set at its lowest output then modulation will not take place. To reduce the time taken for this test, it may be necessary to reduce the heating load by turning off some radiators.
If power has been switched off or CH demand has been interrupted, there will be a delay of between 1 and 3 minutes before the boiler starts.
When U-gauge is removed, test point should be tightened and checked for gas soundness.
Isolate as per TOPs P4
and refit as necessary