How far down can a P-trap be

[Anonymous]

I bought a house that was built in 1959 in Southern Florida. I looked down the shower drain and it looks like the p-trap is 14 inches (I stuck a tape down) down. Is this something the builder did, or is it down that far so it can feed into the 4" waste drain that it goes to? The pipe is copper about 1 1/8 if that sounds right?

I plan to relocate the shower and wonder if just need to repete this setup or, can I use a higher p-trap if I feed it intoa new wet vent.

This low p-trap also makes a lot of noise. Thanks in advance for any advise.

Tom

[Wgoodrich]

YOU SAID;
I looked down the shower drain and it looks like the p-trap is 14 inches (I stuck a tape down) down. Is this something the builder did, or is it down that far so it can feed into the 4" waste drain that it goes to? The pipe is copper about 1 1/8 if that sounds right?

REPLY
The height of the trap is controlled by the height of the vent and the slope of the drain. The shower drain is supposed to be a minimum of 2" in size The trap must be placed a maximum distance of 8 feet from your vent. The drop from the shower to the trap is not so important within reason but there must be a minimum 1/4" slope from the trap to the vent and the vent outlet must be a minimum height above the flood level of the trap. It all ties together to make a picture so to speak.


YOU SAID;
I plan to relocate the shower and wonder if just need to repete this setup or, can I use a higher p-trap if I feed it intoa new wet vent.


REPLY;
The explaination above should show that your existing size shower drain is too small and also should have provided an ideal of placement of the trap in the shower drain design concerning the vent system.

YOU SAID;
This low p-trap also makes a lot of noise.

REPLY;
The noise your hearing is the lack of proper venting causing the weight of the draining water and syphoning effect of that weight of draining water is sucking air through your trap and also sucking the water out of your trap allowing gas to enter you home due to the vent being inadequate causing your trap to become dry because the water was sucked out of your trap due to improper venting. Now the vent without the sealing water in that trap is not being able to seal off the gases of the waste water preventing the trap from being able to protect the house from gases at it is designed to do.

Hope this helps

Wg[/i]

[Anonymous]

The noise I refer to is the water falling the 14" to the p-trap. I also have this with a sink that has the trap 10"down. I thought there is a rule to how far down a p-trap can be down. Like so many times the drain pipe diameter or else the weight of the water can drain the p-trap

On the sink can I off set the bowl drain pipe a little in order to quite it a little. I know this sounds a little off but I want to make things run fine.

Thanks for the reply on the shower. It really helped.

Tom

[Wgoodrich]

The weight of the water between the inlet and the trap forces water into the trap not out of the trap. The wieght of the water after the trap between the trap and the vent is what sucks the water out of the trap if installed with the vent too small, nonexistant, plugged if a wet vent etc.

AS your water drains out of the shower or sink as long as your sink etc. is full of water you would have no sound other than the sucking of the water out of your sink. This sucking sound is not due to the trap but due to the length from that sink to the vent that stops the suction action. The trap can be anywhere along that distance from your sink to the vent and it would make no difference in sound displayed. The strength of hte suction is the distance between the sink and the vent.

Again you may offset the drain if you like but it will make no difference in the sound of the drain sucking due to the wieght of water between the sink and the vent.

Wg