Tweet
Hope someone can explain this phenomenon. During winter (cold temperature) but not in summer, whenever we use the second floor wash basin (either one of two in the bathroom and they connect to the same pipes), there would be a water dripping sound (about one drop a second) as the waste water drained down the pipe. It sounded like there was a leak in the pipe except that if there was a leak, water stains would have been obvious on the ceiling panel under these sinks in the first floor. But there is none over the past 3 winters that this has been going on. What could be causing this sound ? The house is 10 years old. Pipes are PVC.
-
-
You did not mention what part of the country you live in, but you did say cold temperatures. Cold is an arbitrary concept. Forty degrees Farenhiet is considered a miserably cold winter in Florida, while 30degF in December is a heat wave in Chicago, Cleveland or Boston.
One thought does come to mind though. If you are in a cold northern climate, and if the vertical line in question happens to be running in an outside wall, there is a potential that frost is forming on the inside of the pipe wall, then dripping down the inside of the pipe as it thaws, causing the dripping sound but no leak. -
Thank you, LazyPup for your quick response. The house is in Knoxville, TN. Not too cold in the winter and all installations are inside the heated house. The water temp out of the faucet could vary, my guess, around 65F or higher. The pipes, behind the drywall, could be in the 50's. I have never tried to purposely run the water for long periods of time to see if the sound would stop. (Need to remember to run some experiments on this next winter : long periods of hot water) Come to think of it, the major difference between winter and now is the pipe's temp behind the wall.Comment
-
I have a bathroom sink that does that makes a noise and it only happens when it gets at least 10 degrees below freezing. Here in North Texas, that's several times a winter, but not for long periods.
I would describe the noise as a burping sound and it seems to come from the P-trap in the sink. I can make it stop by closing the drain, so it must have something to do with a pressure differential from one side to the other.Comment
-
I wonder if it could be the expansion of that PVC when the warm/hot water moves through it. We have an upstairs sink that drains to the same stack the toilet is on. If hot water is let to run through the drain, that PVC stack most definatley moves! Touching the tank while the water is running and you can actually feel the movement.Comment
-
Thank you Gary and mrcaptainbob. The p-trap sound is interesting though in my case, it really sounded more like water dripping than burping. It sure felt that way when i am at the first floor right below the sink area. My situation (sink and toilet hookups) is similar to what mrcaptainbob described - dual washbasin next to the toilet of the master bedroom. I should try the "touching" observation come winter.Comment
-
GaryS..You problem is most likely caused by frost closure on the vent stack at the roof.
The code requires that the main vent for a structure must run from the house main drain up and out through the roof undiminished in size (Either 3" or 4" depending on the number of fixtures in the house)
Auxillary vents may be reduced to 1/2 the diameter of the line they serve once they are 6" above the flood level rim of the highest fixture served but in no case may they be less than 1-1/4" diameter.
In geographic areas which are subject to freezing temperatures the auxillary vent must be increased to 3" at least one foot inside the attic space before passing through the roof.
The intent of this rule is to prevent the moisture in the vent air from condensating on the inside of the vent top, then freezing and restricting the passage of vent air.
In recent years we are finding that with the increased insulation often the winter temperature in the attic space is nearly the same as the outdoor temperature, therefore the transition from the reduced size to the full size must be made close to the attic floor rather than at the 1' below the roof as specified in the code.
As you point out in your post, when the drain stopper is open and there is a partial frost closure on the vent stack, air is sucked in through the drain causing the gurgling sound. When you close the drain air cannot get in through the drain and must be drawn through the vent stack. The end result of that will be a restriction in the velocity of flow in the drain pipes, which may cause clogs to form.Comment
-
LazyPup. Wonder if you could help me out by sketching the possible plumbing circuit in my second floor washroom : dual washbasin in front of a drywall. Behind the drywall is the toilet (room) and the shower stall. Would be interested to know how the drains and vent pipe are interconnected. May help me understand my problem more. Thanks.Comment
-
I don't think it's frost related, but rather it's tied in some other way to the temperature. When it first happened I checked the vent as I was thinking along the same line. The odd part is it only occurs late in the afternoon and through the night. During the day it's quiet.quote:Originally posted by LazyPup
GaryS..You problem is most likely caused by frost closure on the vent stack at the roof.
The code requires that the main vent for a structure must run from the house main drain up and out through the roof undiminished in size (Either 3" or 4" depending on the number of fixtures in the house)
Auxillary vents may be reduced to 1/2 the diameter of the line they serve once they are 6" above the flood level rim of the highest fixture served but in no case may they be less than 1-1/4" diameter.
In geographic areas which are subject to freezing temperatures the auxillary vent must be increased to 3" at least one foot inside the attic space before passing through the roof.
The intent of this rule is to prevent the moisture in the vent air from condensating on the inside of the vent top, then freezing and restricting the passage of vent air.
In recent years we are finding that with the increased insulation often the winter temperature in the attic space is nearly the same as the outdoor temperature, therefore the transition from the reduced size to the full size must be made close to the attic floor rather than at the 1' below the roof as specified in the code.
As you point out in your post, when the drain stopper is open and there is a partial frost closure on the vent stack, air is sucked in through the drain causing the gurgling sound. When you close the drain air cannot get in through the drain and must be drawn through the vent stack. The end result of that will be a restriction in the velocity of flow in the drain pipes, which may cause clogs to form.
The house is relatively new and up to code. That sink is the only one on an aux vent and appears to be about 2" pipe, though I have never measured it. It's located about 4' from the main 4"(?) vent. If it is frost plugged, it's in an area not visible when looking down into it.
I'll make a point of checking it again next winter.Comment
Comment