Dripping Viessmann flue

[JohnD]

OOI, do you get water droplets blown out of the flue? in this recent cold weather I'm getting it. I've heard it might be because the fan velocity is high. Mine is a 100.

 

[Agile]

Any boiler can blow droplets of water out of the flue.

Might be more prevalent if the flue angle is wrong.

Tony

 

[JohnD]

there is a definite wet patch on the concrete path below

AFAICT the flue was fitted properly and the internal part slopes upwards outwards

I will put a level on it indoors and see if the outer has any fall.

I have seen flues with a 135 degree elbow on the snout blowing upwards, would that help?

 

[Agile]

Most common flue terminals have a built in slope to the internal tube and therefore should be fitted with the outer tube horizontal.

Viessmann flues have a reputation for ejecting more droplets than some other boilers.

Tony

 

[JohnD]

so what can I do?

 

[namsag]

Well at the time of johnD install there seemed a number of basic errors being made so it would not surprise me if they got something else wrong.
But yes a lot of condensors get drips from the flue tip, but whats the worry JD

 

[JohnD]

wet patch on path at base of wall is undesirable. It is on a windy corner so might fall on my head if I'm walking by or perhaps my car if I park it there.

 

[Agile]

If you closely inspect the inner part of the flue terminal you will probably see that the inside of the tube is smooth.

Most other flues have a small ridge about 2 mm to reduce droplet ejection.

You could dry it throughly and add a small ridge over the lower 45° using soft mastic and see if that reduces the problem.

You should not park cars close to condensing flue terminals!

Droplets falling on the path or your head are unlikely to cause any problem.

If seeing these droplets wetting the path bothers you then throw a bucket of water over the path so that its all wet and the droplets cannot be seen any more.

Tony