Prisma 24/SE Prisma 28/SE, Biasi 24S Biasi 28S

Problem Solution
Boiler on with no demand The DHW microswitch can stick causing boiler to fire up and heat to go round radiators
burner on/off cycling clean venturi in fan, these can get dirty and cause issues
Spark but no ignition

Faulty air pressure switch can have strange effects on igntion, normally causing a weak spark

Honeywell gas valve can stick, should be 80-120 Volts AC between top and bottom pins on igntion box



Biasi HE M96.24, M96.28, Garda HE, Parva HE, Riva Compact HE

Problem Solution
PCB Faults

This PCB is standard across several variants of boiler and gives several faults if not set up to the boiler correctly

1. No hot water - PCB has not been programmed to be a combi boiler

2. No heating - these come set at 24kW and the output has to be changed by a series of button presses, ring Biasi for more info