Correct Placement of P-Trap

tommybuk

Good afternoon folks,

I wonder if anybody could advise where the correct placement and size/type of P-Trap I need under my kitchen sink.

The kitchen has been installed over 3 years and we’ve always had the faint smell of sewer gas and I’ve finally decided to do something about it but I’m clueless as to what I need and where it should fit in.

If anyone is able to help it would be greatly appreciated 😊

Photo attached 👍

There also a dishwasher waste water feed to the right vertical pipe hidden behind the white panel if that makes any difference 🤷‍♂️

Thanks all.

Tommy 

WIAWSNB

There is no 'trap' visible there at all, and it's unlikely there's one behind the rear panel of the unit. 

Easy to add one, tho', and the required parts are readily and cheaply available. 

First, tho', we need to know where the DW waste connects - any chance of a photo?

tommybuk

Hi WIAWSNB

Thanks for the reply, here’s a picture photo of the DW waste pipe and its proximity to the sink.

It’s towards the top of the right hand basin.

Also you’re correct the pipe just passes out the back of the unit to a grid outside. Can’t understand why the fitters didn’t fit one unless that shelf was in the way?

Cheers, 

Tommy 

molerat

I wonder if that bottom elbow could be replaced with a running p trap ? https://www.screwfix.com/p/mcalpine-running-p-trap-white-40mm/47605

bjorn_toby_wilde

molerat said:

I wonder if that bottom elbow could be replaced with a running p trap ?

I was just thinking that looks the easiest. Just swap the elbow for a running p trap if you have enough space below it.

tommybuk

bjorn_toby_wilde said:

molerat said:

I wonder if that bottom elbow could be replaced with a running p trap ?

I was just thinking that looks the easiest. Just swap the elbow for a running p trap if you have enough space below it.

 I was looking at that exact fitting but was unsure if it was the correct one for this application

Tommy

bjorn_toby_wilde

tommybuk said:

bjorn_toby_wilde said:

molerat said:

I wonder if that bottom elbow could be replaced with a running p trap ?

I was just thinking that looks the easiest. Just swap the elbow for a running p trap if you have enough space below it.

 I was looking at that exact fitting but was unsure if it was the correct one for this application

Tommy

Make sure it’s 40mm.  Sink waste is bigger than basin waste.

Eldi_Dos

molerat said:

I wonder if that bottom elbow could be replaced with a running p trap ? https://www.screwfix.com/p/mcalpine-running-p-trap-white-40mm/47605

I think I would go belt and braces and fit trap under sink and one at bottom of pipe from DW just before it exits through the wall, just incase there are any odours from DW pipe, especially while it is in use.

bjorn_toby_wilde

Eldi_Dos said:

molerat said:

I wonder if that bottom elbow could be replaced with a running p trap ? https://www.screwfix.com/p/mcalpine-running-p-trap-white-40mm/47605

I think I would go belt and braces and fit trap under sink and one at bottom of pipe from DW just before it exits through the wall, just incase there are any odours from DW pipe, especially while it is in use.

I’m not sure I follow. Won’t the DW pipe always be above the trap either way?

Lorian

If you fill the sink and let it drain does it gurgle? If so you might need to consider a trap with a built in AAV (mcalpine do one)

It would be best to also make sure that grey hose from the dishwasher goes all the way up to touch bottom of the draining board before coming down to the spigot in the waste to reduce the chance of dirty water passing in to the bottom of the dishwasher. That can produce a similar smell too, and less than ideal.

Eldi_Dos

bjorn_toby_wilde said:

Eldi_Dos said:

molerat said:

I wonder if that bottom elbow could be replaced with a running p trap ? https://www.screwfix.com/p/mcalpine-running-p-trap-white-40mm/47605

I think I would go belt and braces and fit trap under sink and one at bottom of pipe from DW just before it exits through the wall, just incase there are any odours from DW pipe, especially while it is in use.

I’m not sure I follow. Won’t the DW pipe always be above the trap either way?

If you fit trap under sink that with trap any odours in the DW pipework, especially if there is that corrugated flexible hose and stop them coming up the sink hole.
Then another trap before pipework goes through wall, to seal off kitchen pipework from outside drains.