What does the Alpha 27 fault code mean?

Your boiler is shutting itself down because the water inside isn't moving away from the heat source fast enough to keep it cool.

How much does it cost to fix Alpha error code 27?

Typical repair cost for the Alpha 27 fault is £150-300 including labour.

Insufficient primary flow - Rapid temperature rise of primary sensor

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

Each noise points to a different fault.

Sludge build-up — needs flushing, not bleeding.

Safety-critical — turn off, read this.