While you wait for answers, we may have found some information which could help you.
Click here for Water Find AdviseMy heating and hot water do not work and “A03” is flashing?
Chaffoteaux et Maury with no hot water?
Chaffoteaux Mx2 24 error 50?
pressure relief valve?
gas water heater chaffoteaux britony 11t (geyser ) 11 years old?
chaffoteaux calydra 80 combi boiler?