ferroli modena not modulating

[moogwai]

going to an old Modena with scalding hot water when pot is turned to minimum so suspect its not modulating.....not sure this would be a thermistor problem as the boiler continually fires when tap opened....anyone experienced this and know expected voltages at gas valve??? or how to set up the board?? ta. I suspect its a mf03 board)

 

[bewsh]

Thermistors are common on these. Have you checked to see if minimum burner pressure is set up correctly? There's an adjustment on the gas valve which rarely works, but there's also a potentiometer on the pcb which can adjust minimum pressure.

 

[moogwai]

Thanks bewsh....I got hold of the manual and set up the min and max correctly.. Now seems fine.