Vaillant plume management

[Allan]

Vaillant ecoTEC plus, open vent condensing boiler

Just moved into a house, and changed the boiler (same horizontal flue position) to the Vaillant. The flue goes horizontally through the wall, which outside the wall is then about a foot from the property boundary, and then the neighbour's garden. The neighbour has mentioned that on a cool, still day (autumn?), he is getting a large plume from the flue coming across his garden. I don't know what happened with the previous owner/occupant/boiler, but part of me thinks that the boiler/flue was always there. However, he is correct, and I don't want to fall out with him just as we've arrived, and we're getting on fine so far. The boiler is in the garage, underneath a pitched roof, so I suppose I could put the flue vertically, but I don't suppose it'll make much difference on the cold, still day: the plume will still spread, and it'll mean moving the flue (horizontal to vertical, assuming that's possible), and knocking a hole in the roof (which will no doubt have its own issues and costs).

Any suggestions on how to manage the plume?

TIA

Allan

[Dave Liquorice]

Undoubtly but was the previous boiler a condensing one? Flue gases from a non-condensing boiler are hotter than those from a condesnsing one so the water vapour is far less likely to form a visible plume as they will have dissipated before getting cool enough.

The major part of the problem is that the plume is being blown (by the boiler fan) out of the flue horizontally across your neighbours garden. If you shot it into the air vertically and higher up it would greatly improve things.

How one arranges that I'm not sure. Have a google to see what flue kits are available for your boiler. It might be possible to put a vertical extension onto the existing through wall flue. How big any eaves are might make things trickier.

There is a 52 page .pdf flue installation guide on the valliant web site.

[rbel]

Given my own experience of this I suggest that to a degree it is a question of perception. Both of our immediate neighbours have boilers in garages. It occurred to me last winter that whilst I noticed the plume from the horizontal flue because it is within my normal field of view, I had never noticed that from the vertical flue although, height-wise, the outlets are only a bit over a metre apart.

As you indicate, it is on cold but relatively still days that the plume is apparent. Luckily we live in a rather exposed location so very still days are few and far between.

Re-positioning the flue would certainly show good intent, it is a question of balancing goodwill against cost and inconvenience.

-- rbel

[Lobster]

+1

For the avoidance of doubt, don't be tempted to bodge it yourself with drainpipe or something; the output characteristics of the flue (apparently) impact on the overall safety of the boiler etc; so just use whatever kits are available.

I had a plume issue with a very early model condensing boiler (early, as in there were no flue extension kits available as the plume problem had not really been identified) and I positioned a flat piece of aluminium a couple of inched away from the output at 45 degrees, to divert the plume sideways. Wasn't even touching the flue output, but when a CorgiGuy saw it a few months later he threw a wobbler and removed it :(

David

[John Rumm]

There are a multitude of flue options, however the simplest would seem to be the Variable Terminal Kit:

for part number 303942) and section 3.7