Does anyone know what U9 means. I have had my worecester greenstar 35 CDI RSI for 5 years. U9 is flashing. Can anyone help me with this information[/code]
u9 is a blocking stage where the boiler is protecting itself. It means the primary temp has reached 109 degrees and so the boiler switches the burner off until such time the temp measured within the boiler drops.
Is there air in the system?
whats the pressure...is it at 1-1.5 bar?
Is the pump running?
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