Condensation

jaggiebunnet

Hi - hopefully i explain this well enough that someone understands!

I have 3 pipes in the attic that are joined to external vents via flexible pipes, my understanding is that these help remove hot air from the house and stop it condensing in the attic ( probably wrong but anyway..). So my problem is where the pipe on the vent joins the pipe in the house there is water dripping, particularly during cold weather as you would expect with condensation. The pipes are joined by large jubilee clips but though these are tight they do not seem to stop the build up below where it has been placed. Should I look to seal the pipes with something in addition to the jubilee clip? If so what is recommended?

Billy Bunting

Pictures may help.

jaggiebunnet

Yeah sorry meant to get these up, only managed to get back up to attic last night.

If you look you can see the water dripping at the joint.

Billy Bunting

jaggiebunnet wrote: »

If you look you can see the water dripping at the joint.

Are you sure what your looking at isn't silicone sealant ?

jaggiebunnet

no - definitely water there is no sealant there, I can wipe it away and it will come back (and drip on the floor). Would applying some silicon sealant here be the thing to do ?

rightjob!

are they from two bathrooms them pipes?as in the extractor fan?

MicktheMan

I'm not sure whether the system is a mechanical or passive stack ventilation from the pics but in any case what is probably happening is the ventilation is working, in that, warm moist air is being expelled out of the house through these ducts. That is good as in that is what should be happening.
What appears to be the problem is the ductwork in the cold attic is un-insulated causing the moist air in the ducting to condense on the inside of the cold ducting which is then running down and leaking at joints. More condensing will occur during colder weather.
Adequately insulating all the exposed ductwork will reduce or eliminate this condensation problem and allow the system to carry all the moisture outside as designed.

NewBeefFarmer

1, its for hot damp air from the house, its condensing inside the cold pipe, turning to water, back flowing to a joint and out. ... make sure its sealed and the pipe itself should be insulated to stop it reaching low temps.

2, it could be for carrying water, to me the white pipe is used for waste water. . and all vent pipes are usually 4 inch flexi. . and if its for water, its just leaking



but if ur 100% that its air in it, which id say you are, then No 1 is you prob

jaggiebunnet

MicktheMan wrote: »

I'm not sure whether the system is a mechanical or passive stack ventilation from the pics but in any case what is probably happening is the ventilation is working, in that, warm moist air is being expelled out of the house through these ducts. That is good as in that is what should be happening.
What appears to be the problem is the ductwork in the cold attic is un-insulated causing the moist air in the ducting to condense on the inside of the cold ducting which is then running down and leaking at joints. More condensing will occur during colder weather.
Adequately insulating all the exposed ductwork will reduce or eliminate this condensation problem and allow the system to carry all the moisture outside as designed.

Thanks! Yeah going by a quick google on Passive / Mechanical stack ventilation that would definitely appear to be the setup (extractor fans in bathrooms seem to line up with main pipes going to the vents). One of these bathrooms is never used but obviously the hot air is rising through the house.

Is there any special insulation I should use or will regular attic insulation do the job?

MicktheMan

jaggiebunnet wrote: »

Is there any special insulation I should use or will regular attic insulation do the job?

There is specific duct insulation available but, imo, well installed attic fibre insulation is just as good so long as it is done properly with no gaps.

kenobee

You might also get a tube of Tech 7 sealant and apply it around those joints. It can be applied even on to wet surfaces