Condensation on an ABS vent pipe in bathroom

[jgraf]

Hello there, I'll try to explain my problem as best as i can, i live in Manitoba which we all know can have some pretty terrible weather. Over the last week or week and a half i noticed a lot of moisture or condensation on an ABS pipe that comes out of the wall and into the cabinet of my sink in the bathroom. it looks like a 1 inch or 1 and 1/4 inch pipe. 1st question is this a vent pipe? and second question where is all this moisture coming from? I had a plumber open the wall and spray foam where the elbow joint is right at the ceiling and he also went in the attic and sealed around the main stack. Im pretty stumped here and the issue doesnt seem to be going away. Any ideas as to what i can do?

[Aaron]

If you touch the pipe, is it really cold?

[jgraf]

Not like super cold but yes it's cold

[Shannon]

I'm sure its a vent. If its been pretty cold outside the air in the pipe is cold and the warm air of the house is causing condensation on the cold pipe. This would be my guess. Is this an issue you have never noticed before? Maybe your humidity in the house is higher then usual?

[jgraf]

Never noticed it till the water pooled in the basement, the humidity has been pretty normal in the house nothing more then usual. I thought maybe the stack isnt sealed off properly or something at the attic. The amount of moisture on the pipe too is quite a lot. Would insulating the pipe do anything?

[jgraf]

Another question would be why does it.clear up.when it's nice out?.

[jgraf]

Hi there, would it be possible if a toilet in a different bathroom was leaking would that be enough to cause condensation on the pipe in the other bathroom?? Just racking my brain here trying to figure out what it could possibly be

[Aaron]

It's weird to say the least. ABS doesn't conduct heat or cold very well anyway, and even if the pipe carried ice cold water it's hard to imagine it being so cold that condensation would form on it?

I think the moisture you're getting may not be condensation but a small leak of some sort running along the pipe.

The weather could be a factor but correlation is not necessarily causation. I think you just have to chase the pipe up and see where that water is coming from? That's the only advice I can offer unfortunately!

Intermittent trouble is the worst, too.

[jgraf]

It's weird to say the least. ABS doesn't conduct heat or cold very well anyway, and even if the pipe carried ice cold water it's hard to imagine it being so cold that condensation would form on it?

I think the moisture you're getting may not be condensation but a small leak of some sort running along the pipe.

The weather could be a factor but correlation is not necessarily causation. I think you just have to chase the pipe up and see where that water is coming from? That's the only advice I can offer unfortunately!

Intermittent trouble is the worst, too.

So even if it is intermittent theres a possibility it's still a leak? The pipe will totally dry up some days to not even a bead of water which is why I find it hard to believe. I'm leaning more towards a humidity issue and maybe wrap the pipes in the attic with some sort insulation

[Aaron]

So even if it is intermittent theres a possibility it's still a leak? The pipe will totally dry up some days to not even a bead of water which is why I find it hard to believe. I'm leaning more towards a humidity issue and maybe wrap the pipes in the attic with some sort insulation

Sure, give it a go. Your guess is as good as mine, honestly.

Sort of a silly experiment but I wonder if you can duplicate the problem? Does a glass of ice water have condensation any time the pipe does? Because there should be no circumstances where the pipe would have condensation and not the glass, which could rule out condensation.

[Shannon]

Ya this is a weird one if it is actually condensation. Sorry at this time I have nothing else coming to mind . let us know if you figure something out.

[jgraf]

Yeah it is weird I've been talking to a guy local to where i am and he says to wrap the pipe in the attic and run the HRV system more to help keep the air moving. I'll post back with results in a few days thanks for your help

[Shannon]

Seems odd that the pipe would be cold enough all the way down in the basement to allow condensation .

[jgraf]

Seems odd that the pipe would be cold enough all the way down in the basement to allow condensation .

No, it's the pipe in the upstairs bathroom sorry, what I meant was it drips down following the pipe into the basement so it builds up in the upstairs then kinda drips down following the pipe. Sorry for the confusion.

[Shannon]

OH I see now. Ok I can see that pipe maybe being cold enough if its only 8' or so from cold attic and end of open pipe on roof.
Yup ,try wrapping the pipe with insulation in attic and see what happens

[jgraf]

OH I see now. Ok I can see that pipe maybe being cold enough if its only 8' or so from cold attic and end of open pipe on roof.
Yup ,try wrapping the pipe with insulation in attic and see what happens

Yeah I've wrapped the pipe was a tight fit hopefully it did the job though and I'll continue to monitor...the stack on the roof itself is open should I be getting a cover or something maybe??

[Shannon]

No the pipe up top does not get covered.

[Aaron]

It's just odd to me that ABS pipe could get that cold. ABS doesn't conduct temperature that well, or so I thought. This is a very unusual situation if it's condensation.

[jgraf]

It's just odd to me that ABS pipe could get that cold. ABS doesn't conduct temperature that well, or so I thought. This is a very unusual situation if it's condensation.

Yeah I find it really odd as well, like for example it's been hovering around zero Celsius here and the pipe is bone dry ...I'm waiting for a change in weather right now to see what happens. If it were a leak wouldn't it be constantly happening? Just seems really weird

[Shannon]

Maybe its just the right conditions at the right time causing it? Cold air in pipe and warm moist air in the bathroom

[jgraf]

Yeah i guess that would be possible. I've been advised to run my air exhanger more often which I've been doing, I'll continue to monitor the situation but as of now it's dry

[jgraf]

Hi there havent posted for a while as I had hoped the problem had fixed itself....I was wrong. So since my last post I had wrapped the vent stack in the attic with some insulation and I was waiting to see what happened when it got a little colder. Last night was finally a lot colder and this morning the pipe had frost on it right where it comes outta the wall. The humidity level in the house is low so I dont think it's that anymore. I was wondering what your guys thoughts would be? Wall not insulated properly? Thanks for your help.

[Shannon]

I see you never posted a picture of the pipe and situation , maybe that may help us?
It could just be that the pipe is cold in the wall and no insulation around it so the cold pipe frosts up on the warm side of the wall when the temps drop?

[jgraf]

I see you never posted a picture of the pipe and situation , maybe that may help us?
It could just be that the pipe is cold in the wall and no insulation around it so the cold pipe frosts up on the warm side of the wall when the temps drop?

Ok so I think I attached a picture hopefully it worked, it's from a few weeks ago but as of today the whole pipe that I can see under the sink is covered in frost. Would it be a good idea to open the wall and wrap that pipe in insulation?

[Shannon]

ok so I will guess that it is just because the pipe is cold right in the other side of the drywall and then the warm air and lack of air flow in the cabinet allow moisture to condensate on the cold surface of the pipe. Insulating around this entire pipe may help but it may just frost up below the floor where you can’t see it? Not sure there is a perfect fix but I’m not sure that it is a huge deal either unless the pipe is really dripping moisture and causing moulding issues in the cabinet?

[jgraf]

ok so I will guess that it is just because the pipe is cold right in the other side of the drywall and then the warm air and lack of air flow in the cabinet allow moisture to condensate on the cold surface of the pipe. Insulating around this entire pipe may help but it may just frost up below the floor where you can’t see it? Not sure there is a perfect fix but I’m not sure that it is a huge deal either unless the pipe is really dripping moisture and causing moulding issues in the cabinet?

Whats actually happening is it follows the pipe into the basement where it pools down there ..tried spray foaming the bottom part of the cabinet but it seems to make it's way through

[Shannon]

Well I would wrap pipe insulation around it or cover it in bat insulation and cover it in and see if that stops it.

[jgraf]

Well I would wrap pipe insulation around it or cover it in bat insulation and cover it in and see if that stops it.

So we cut the wall open and that's what it looks like...everything looks like its insulated well but the pipe is really cold to the touch. Figure just wrapping the pipe will fix the problem??

[Shannon]

I ment covering the exposed pipe in cabinet. The pipe is in a cold zone (in wall) nothing you can do with that area

[jgraf]

I ment covering the exposed pipe in cabinet. The pipe is in a cold zone (in wall) nothing you can do with that area

Yeah, I wanted to make sure behind the wall was ok, seems like the only major frost build up is where it comes into the vanity. You think if I wrapped the pipe in the vanity and then wrapped the pipe in the basement that might stop it from at least dripping down there? When it's all frosted up doesnt seem to be a huge problem obviously it's just when the pipe starts to thaw out a bit