How much does it cost to fix Remeha error code 6.4.7 Down draft thermostat?

Typical repair cost for the Remeha 6.4.7 Down draft thermostat fault is £120-250 including labour.

6.4.7 Down draft thermostat Emergency

Remeha 6.4.7 Down draft thermostat Fault Code

Q: What does the Remeha 6.4.7 Down draft thermostat fault code mean?

Your boiler has detected that exhaust gases are being blown back into the unit instead of venting safely outside, so it has shut itself down to prevent a fire or carbon monoxide risk.

Also written as 647DOWNDRAFTTHERMOSTAT — same fault.

The Remeha 6.4.7 Down draft thermostat fault code means: your boiler has detected that exhaust gases are being blown back into the unit instead of venting safely outside, so it has shut itself down to prevent a fire or carbon monoxide risk.. It appears on 2 Remeha models in our database.

Technical description: (optional, shut down)

Typical repair cost £120-250 (including labour)

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

Find a Gas Safe engineer

Search the official register for a qualified engineer in your area.

Gas Safe Register →

Remeha models that show the 6.4.7 Down draft thermostat fault code

Click a model for the full fault code list and model-specific repair notes.

Source

Remeha 6.4.7 Down draft thermostat fault code information on this page is sourced and cross-checked against the official Remeha service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026