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What is a 'P' trap - Printable Version

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What is a 'P' trap - Cecil - 04-02-2017

My washer drain has an S trap.  I need to make some changes in that area, so I want to bring it up to code.  What is the minimum length of the trap arm for a 'P' trap.  Thanks


RE: What is a 'P' trap - Roly - 04-02-2017

Is this what your doing ?   If so two times the trap diameter.    Roly
[Image: 60397d1353509522-s-trap-plumbing-s-trap.jpg]


RE: What is a 'P' trap - Cecil - 04-02-2017

Yep, that is exactly what I am doing.  Thanks


RE: What is a 'P' trap - Roly - 04-02-2017

Note how it is measured.     Roly


RE: What is a 'P' trap - blackhat - 04-03-2017

That would be better if there was a vent or AAV on the vertical.


RE: What is a 'P' trap - Snipe Hunter - 04-04-2017

The reason we no longer use P-Traps is because they siphon the trap dry, making them useless.


RE: What is a 'P' trap - Stwood_ - 04-04-2017

(04-04-2017, 06:30 AM)Snipe Hunter Wrote: The reason we no longer use P-Traps is because they siphon the trap dry, making them useless.



Ahha. Learn something every day.
Laugh

So our kitchen drain is that way (old way). But I don't see a way to change it, as the waste pipe is right there by the sink outlet. My trap is twisted back around itself


RE: What is a 'P' trap - Roly - 04-04-2017

(04-04-2017, 06:30 AM)Snipe Hunter Wrote: The reason we no longer use P-Traps is because they siphon the trap dry, making them useless.

Do you mean S traps instead of P traps ?   Roly


RE: What is a 'P' trap - Cecil - 04-04-2017

(04-04-2017, 06:30 AM)Snipe Hunter Wrote: The reason we no longer use P-Traps is because they siphon the trap dry, making them useless.

(04-04-2017, 12:37 PM)Stwood_ Wrote: Ahha. Learn something every day.
Laugh

So our kitchen drain is that way (old way). But I don't see a way to change it, as the waste pipe is right there by the sink outlet. My trap is twisted back around itself

The 'S' trap may allow a siphon, not a 'P' trap, according to what I find (https://www.youtube.com/watch?v=bU8aMK2NmI8).  This happens when a high volume of water is drained.  When a toilet drains, it always empties enough of the trap to break the seal and let the sewage gasses into the house.  However, the toilet also replenishes the bowl, to refill the trap.

In my case, I recently purchased a wood shop with a house attached.  The previous DIY owner made many errors.  A laundry was added, with an 'S' trap and no vent on that end of the house.  I am putting on a roof, so I am taking this opportunity to add a vent and, at the same time, putting in a 'P' trap.  I will need to update the kitchen and bath sink as well, eventually.  In the meantime, any time I pull the plug to drain a sink, I remember to follow up with a little from the tap.


RE: What is a 'P' trap - Snipe Hunter - 04-06-2017

(04-04-2017, 12:43 PM)Roly Wrote: Do you mean S traps instead of P traps ?   Roly

Yea oops. Sorry fellas.