F.53
FAULT CODE
Vaillant
DHW Flow Rate Too High
Medium Severity
Engineer Required
The domestic hot water flow rate through the boiler is too high, preventing the water from being heated to the correct temperature.
Step-by-Step Fix Guide
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Step 1
Check that thermostatic radiator valves and zone valves are operating correctly
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Step 2 Engineer only
A Gas Safe engineer should investigate the DHW circuit flow rate
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.