NModulating Valve Check
Is minimum pressure | YES | Remove X6, measure |
observed at burner at all |
| resistance between |
| ||
times? |
| pins 15 & 16 |
NO
GO TO | NO | Is resistance |
| ||
CHECK I |
| nominally 125ohms |
Is pressure at burner YES always the same?
NO
Gas valve OK
Flow Switch Check
Remove X6
Close all taps to set no
domestic flow
With pressure above
minimum, remove Modureg Lead. Does pressure drop to minimum?
YES
NO Faulty modulating valve . Replace gas valve
YES
YES
Reconnect X6 and measure voltage across modulating valve during operation
Does voltage go above 6.25V
NO
Faulty PCB.
Replace
Is open circuit observed NO at X6 pins 1 & 2?
YES
Open a tap fully to set
domestic flow
Is short circuit observed NO at X6 pins 1 & 2
YES
Faulty flow switch.
Replace
GO TO | HARNESS OK |
Faulty flow switch. | |
CHECK I | Replace |
Flow Switch OK
33
