109
FAULT CODE
Ariston
System Pressure Too High (Clas Net One)
Medium Severity
Engineer Required
On Ariston Clas Net One boilers, code 109 indicates system pressure has exceeded 3 bar.
Step-by-Step Fix Guide
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Step 1
Do NOT add more water
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Step 2
Check the filling loop is fully closed
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Step 3 Engineer only
Call a Gas Safe engineer to operate the pressure relief valve if pressure remains above 3 bar
Gas Safe Reminder
Work on gas appliances must be carried out by a Gas Safe registered engineer. The steps above cover safe checks a homeowner can perform - any internal component replacement requires a qualified professional. If in doubt, always call an engineer.