Really strong smell coming from your back boiler when you turn on the heating It smells like the fumes are entering the room you have turned off the gas hoovered all the dust out please help?

It is important that you do not use the boiler and turn the gas off. You must then ask a professionally qualified gas plumber or engineer to come and test and overhaul your boiler. If you do not do this your boiler could let Carbon Monoxide gas into your house and this will kill you. Don't mess with Gas!!!