F.24
FAULT CODE
Vaillant
Flow Temperature Rising Too Fast
Medium Severity
Engineer Required
The boiler flow temperature is increasing too quickly, suggesting insufficient water flow past the heat exchanger. Common causes include a failing pump or airlocked system.
Step-by-Step Fix Guide
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Step 1
Check system pressure
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Step 2
Bleed all radiators starting from the ground floor
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Step 3
Reset the boiler
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Step 4 Engineer only
If the fault returns, an engineer should test the circulation pump
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.