Gas heating engineers? - Tech question re plume management

[pstruck]

I think I've worked out that the excessive condensation which drips of the felt in our loft is coming from the exhaust plume from our condensing boiler, which is situated on the single storey extension to the rear of the house.

It seems that the plume rises from the external vent and in the right conditions enters the soffit vents and into the main roof space.

I've read a little about 'plume management kits' which extend the position of the vent plume away from windows etc, but I would need about 10m of pipe to get the vent along the wall of the extension, then up and above the gutter height of the main roofline.

Is this my only option, or is there any way to capture the vent plume and condense it so that the escaping vapour is reduced or eliminated?

[dirkgently]

pstruck said:

I think I've worked out that the excessive condensation which drips of the felt in our loft is coming from the exhaust plume from our condensing boiler, which is situated on the single storey extension to the rear of the house.

It seems that the plume rises from the external vent and in the right conditions enters the soffit vents and into the main roof space.

I've read a little about 'plume management kits' which extend the position of the vent plume away from windows etc, but I would need about 10m of pipe to get the vent along the wall of the extension, then up and above the gutter height of the main roofline.

Is this my only option, or is there any way to capture the vent plume and condense it so that the escaping vapour is reduced or eliminated?

What are the distances from the flue to the vents?

[pstruck]

Approx 5 metres. I been wracking my brain about the condensation in the loft, but then I noticed the vapour plume wafting around the back bedroom window, immediately below the soffit vents where I assume it is entering the loft.

[dirkgently]

I have to say that at a distance of five meters I would have thought the plume was too diluted to cause problems in the roof.

[pstruck]

I thought the same at first, but the condensation in the loft is only in the area adjacent to where the plume is rising from. It has been very cold here recently and the external surface of the roof has been covered in frost regularly. My thought was that warm vapour rising and entering the loft void may condense out on contact with the very cold inside of the roof. Also, it does seem a very prominant plume which is easily visible in these cold conditions well beyond the roof line.

[GreenV8S]

Block off the vents on that side and see if the condensation problem goes away?

[pstruck]

GreenV8S said:

Block off the vents on that side and see if the condensation problem goes away?

'tis a good idea.

[dirkgently]

If it is an occasional problem I think the roof will cope.

[pstruck]

It's all the stuff in the loft getting wet that concerns me more.

It is dripping to such an extent that there are small puddles on the boarded sections. It will soak through the ceiling eventually I'm sure.

[dirkgently]

That sounds like a bigger problem than a flue plume.

[pstruck]

Going to give the 'block up the vents and see what happens' idea a go.

May also look to re-direct plume. Are there any pitfalls I should be aware of if extending the vent?

[dirkgently]

pstruck said:

Going to give the 'block up the vents and see what happens' idea a go.

May also look to re-direct plume. Are there any pitfalls I should be aware of if extending the vent?

Read the manufactures instructions regarding the flue and flue management kits.