High
d1 on Vokera Syntesi 29

Your boiler's waste water pipe is blocked or frozen, preventing the system from draining properly and causing it to shut down for safety.

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

What the manual says

Manufacturer manual

The condense trap/pipe has become blocked.

From this model's manual
Verified against the Vokera Syntesi E installation & service manual, page 32.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

What causes this fault?

This fault occurs when the liquid produced by the boiler during operation cannot flow away, causing it to back up into the system. The most common reason is a blockage in the drainage pipe, often caused by a buildup of debris in the internal trap or ice forming in the external pipework.

This fault is significantly more common during winter, as the external condensate pipe can easily freeze during cold spells and prevent water from leaving the boiler.

Engineer required

This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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