Old tub with no vent, and it drains! Why?!

Jpb116

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• Feb 19, 2008

• #1

So I have a tub/shower on the main floor of a ranch. It's 40 years old and during a remodel I've opened the ceiling below it (finished basement) The tub doesn't have a vent. Just the standard drain, trap etc. It's about 8 to 10 feet from the main drain out of the house. So how does this thing drain okay? Is it venting through the overflow? And lastly, can I plumb the new tub the same way?

 

Krow

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• Feb 19, 2008

• #2

It has to have a vent (unless a previous owner made his own plumbing codes). Is there a branch within 5' of the bath trap? A lav/basin drain?

The vent is there to keep water in the p-trap from being siphoned out.
Its not being vented from the overflow.

And lastly, can I plumb the new tub the same way?

Click to expand...

Not by any code that I am familiar with. You need to have a dry vent or a wet vent with in 5' of the fixture trap

 

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Jpb116

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• Feb 19, 2008

• #3

just checked again ...

The nearest vent is upstream and about 7 feet away...

 

Krow

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• Feb 19, 2008

• #4

jpb116 said:

The nearest vent is upstream and about 7 feet away...

Click to expand...

can you tell if its a dry vent or a wet vent?


Which ever one it is, we may be able to make it work for your application with a little bit of altering.

A pic of the area would be helpful to see what room you have to work with

 

Jpb116

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• Feb 19, 2008

• #5

it's a dry vent ...

All this being said, My intent is to demo the area... I'm going to vent to code in the rebuild. I was just curious how it would actually drain in this configuration ... mabe lucky?

 

Krow

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• Feb 19, 2008

• #6

Here are 2 typical examples of dry venting and wet venting. If you decide to go with either one, we can help you with the sizing of piping

 

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hj

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• Feb 20, 2008

• #7

vent

In most cases a vent has little to do WITH draining, it comes into play AFTER draining has finished so that the process does not compromise the trap's seal. As a practical matter, most drains would work much better without a vent, because siphonic action would be more effective than hydraulic pressure.