External boiler flues

[eagleeye]

Would anyone be able to tell me if a Vaillant flue can be run vertically externally?

I know you can with Viessmann and Worcester but cant remember about Vaillant

Thanks

 

[ShaunCorbs]

Vaillant can’t I believe or has to be coated eg painted

 

[Harvest Fields]

Yes you can mate. But the collars have to have a bead of silicone around the top and bottom.