F26
FAULT CODE
Saunier Duval
Maximum Delta Temperature
Medium Severity
Engineer Required
The temperature difference between flow and return is too great — water circulation fault or flow/return connections swapped.
Step-by-Step Fix Guide
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Step 1
Check that flow and return pipes are connected correctly
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Step 2
Bleed radiators
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Step 3 Engineer only
Call a Gas Safe engineer if fault persists
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.