need some advise on a existing vent to a replacement mws tank. A new grp tank erected to replace an old braithwate. The fitters have said that they cant terminate the existing 65mm vent in the tank It has to go to a tundish then to outside. They have advised us that it comes under the new by-laws. I can see their point as the water being vented will be hot and could contaminate the storage water (legionella etc) and could be a dead-leg for an unknown period. They do this all day and i have no reason to question their concerns however the guy running the job has asked me so i'm asking you guys. It's a 4000L breeched jobbie so not domestic. I'm not up on current by-laws so any help much appreciated