F19
FAULT CODE
Glow-worm
Flow/Return Differential Too High
Medium Severity
Engineer Required
The temperature gap between flow and return is too large, indicating poor circulation.
Step-by-Step Fix Guide
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Step 1
Check system pressure
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Step 2
Bleed radiators
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Step 3 Engineer only
A Gas Safe engineer should check the pump and system for blockages
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.