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Sink Drain question

Posted by f1fan (My Page) on
Sat, Jul 25, 09 at 12:04

I just unclogged a TON of the wife's hair out of the bathroom sink (because the water was draining really slow...and no, she's not balding.).

Now, if I fill the sink w/cold water, it drains out faster than HECK and even creates an eddy.

However, if I fill the sink w/hot water, it drains really slow and occassionally, bubbles will come up out of the drain.

What gives? Is there some law of physics that says hot water drains a LOT slower than cold?

Thanks in advance!


Follow-Up Postings:

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RE: Sink Drain question

I know that hot water can soften PVC drain pipes causing them to sag in the middle of long unsupported runs. Maybe a pipe starts sagging causing an uphill climb on the downstream end? Seems like it would take a lot of hot water to soften the pipe that much though... Or maybe the hot water is softening something in the sink drain-stopper causing it to sag and block the drain... ? I am not a plumber :)


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RE: Sink Drain question

Well, the pipes won't sag when you use hot water and then go back to normal when you use cold water again next time. So I doubt that that's the issue. Maybe try lukewarm water and see if that makes a difference also, that would suggest that something does soften above a certain temperature.

I also had similar problems with my wife's hair, have a look at the drain traps on the link below, still haven't purchased one but I wonder if they do what they promise.

Here is a link that might be useful: Non-clogging drain traps


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RE: Sink Drain question

The only explanation I can think of is that the hot water is softening up the residual goo (technical term) that's lining the pipe. Maybe filling the bowl with hot water + detergent will release more goo and wash it down the drain.


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RE: Sink Drain question

i am having the same problem with my new sink! it has only been 2 days since a complete new sink has been installed in my new bathroom. so definitely the pipes are not clogged.Has anyone been able to resolve this issue??
However, i tried the solution posted by homebound and everytime i pour detergent in the still hot water sitting in the sink, the water instantly drains out. but if i open the Hot Water again...the same thing, it won't drain. what to do?? please advise. any suggestions will be appreciated. thanks.


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RE: Sink Drain question

Hot water warms the air, and warm air rises, lowering air pressure at the surface. That's weather. You have a microclimate. Rising moisture and warmer air create a column of low pressure above the sink. It must be creating enough uplift to counteract the usual effects of gravity and atmospheric pressure. With cold water and typical high pressure, I would expect water to flow down through plumbing faster. This might just be an extreme case. A partially clogged drain or vent wouldn't help.


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RE: Sink Drain question

Shipshape I don't know if you're right but that is one great answer!


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