Home>Discussions>PLUMBING>reducing a 4" crock to 11/2" for a launder tub drain.
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Dennis Holiday
reducing a 4" crock to 11/2" for a launder tub drain.

I have an old old (130 + yrs) house and in the basement the previous owners ran a 2inch straight pipe from the laundry tub straight down to a 4 inch hub as the drain and didn't seal it. the hub I suspect was the floor drain because it is actually a trap right under the floor. I expect this is good news because it keeps any sewer gas from coming back threw the line. the hub is actual the orange fired clay type. The problem i have is that the laundry water comes out to fast for the floor drain to move it and the corner of the basement floods to about 3/4 inch of water covering a square yard of the floor before it has a chance to drian off. The drain is in the floor about 12 inches from one wall and 30 inches from the other. It is not a bad corner for my laundry tub so What i want to know is if i can reduce the 4inch ID hub to match the 1 1/2 inch drain and trap for the laundry tub. AND . with the way that floor drains are done can it drain off the amount of water i have or will it drain too slow to put the laundry water thru it. If I can use this, how would i seal the 3inch or 4 inch reducer into the 4 inch hub?

Re: reducing a 4" crock to 11/2" for a launder tub drain.

First a floor drain should be going to a storm sewer not a waste sewer and you should not be running gray water into it.

Second if you seal it you have no floor drain and if you have water leak the water will just fill up your basement.

That being said the cause of your problem is the fact that it takes a certain amount of pressure to force the water Through the trap and it is easier for it to over flow because water takes the path of least resistance. You could take a piece of 4"PVC about 2ft long and silicon it into place to create a stand pipe. Then run your 1½" pipe into it. The dam created by the stand pipe will build enough pressure to cause the water to go down the drain rather than out on the floor.

Re: reducing a 4" crock to 11/2" for a launder tub drain.

good morning dennisit sounds to me as if you have a main drain blockage.
before you do anything with your laundry this problem must be addressed.
question: are there large old growth mature trees in the area where the main drain leaves the dwelling?
if so dollars to doughnuts there will be roots in the clay sewer lines.
i don't know how handy you are but it's not a bib job to rent an auger and clean the drain, after you clean the drain, then it's not going to matter how much waste goes down the laundry.
caution! do not block your only floor drain in the basement,youmay not be covered inthe event of a flood.

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