Leisure battery ventilation

I have a 2008 Autosleeper Devon.  I am replacing the leisure battery under passenger seat but can not find a vent hole for the battery vent pipe to the open air under the seat box.  I have contacted Mark at Autosleeper re this but he replied that the leisure batteries were fitted by Mercedes and he does not know if such a hole exists.   Can anyone tell me if there is a hole through the cab floor  if so where please. Without one there is a serious risk of a gas build up, in the vicinity of a battery charger, plus I dont really want to drill a hole through the cab floor.

I have a 2010 Devon, I had the Leisure battery replaced by a local Auto Electrician and he drilled a small hole in the floor adjacent to the battery big enough to take the vent tube. making sure that there were no obstructions beneath, he painted around the new hole to stop rust. problem solved
Pete C

So are the batteries being replaced sealed ones with no vent tubes?

Not sure about that Paul but autoelectrician couldn't find an hole in the floor and my old battery had disintegrated.

Mine is a leisure battery with a vent tube

constable wrote:Mine is a leisure battery with a vent tube

So it simply vented inside!