Our flue from the boiler goes out through the roof of the house. I'm told that Vokera, who make the boiler, use internal flue caps. Is this right. There is no cap on the roof where the pipe meets the tiles and you can see a fair bit of daylight from under the eaves, but so far no rain appears to have come through.
A gas engineer has advised that an external cap is needed (ie on the roof) to stop any water getting in and to stop carbon monoxide, which the pipe takes away, from re-entering the house after it goes out through the pipe. he has said to fit an external cap will cost £450.
Do I need this?