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I need to replace the trap under my kitchen sink with one with a horizontal nozzle. However, the new trap won't quite fit.

The existing situation is in the below photo. The outgoing pipe from the existing trap (green dot; waste pipe?) is slightly higher than where it would be for the new trap.

I've struggled to find anything online about it because I don't know what to search for - in most of the stuff online the trap connects to a neat pipe that goes into the wall. Instead here I have a curved pipe (red dot) that leads to whatever that grey thing is in the bottom left of the photo (blue dots). The curved pipe and its parts can't be pulled apart or twisted, not by hand at least.

My key question is - how can I connect my new trap, with a slightly lower outgoing pipe? A subsidiary question - what's the right terminology for the things indicated by the red and blue dots?

trap

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    The terminology I'd use is %@$#&*! creative plumbing, but that's not a technical term ...
    – brhans
    Mar 8 at 2:57
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    A couple of glued together 45 degree couplings with some short pieces and a straight coupling. With such short pieces they all have to be replaced because they were glued together, is that an AAV or air admittance valve in the back? These should always be replaceable, but that is my opinion
    – Ed Beal
    Mar 8 at 3:20
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    The camera angle needs to show the 2 lines better( one small blue and the light colored corrugated line up top ). Do you know what they are for? My guess for the blue one is the supply for the dishwasher but the picture makes it look like it is possibly tied into the drain. The corrugated line should the waste line for the dishwasher.
    – Jack
    Mar 8 at 4:18
  • Is this in the USA or UK? If it is the UK, that may explain why it is so different than what I am familiar with. The plug connector on the left side of the picture, tells me it is not in the USA...
    – Jack
    Mar 8 at 4:22
  • The bottom blue dot may be a "drum trap". As Ed writes, the upper blue dot looks like a one-way air-admittance valve, since there is no vent stack visible.
    – Armand
    Mar 8 at 8:14

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You're asking how to adjust the glued up plumbing to match up with the new trap you've purchased. I'd suggest that the much easier option to is to return the new trap you've purchased and buy a different one that fits the existing glued up plumbing.

However, if you're set on using the trap you have in hand...

You cannot undo the section of piping identified by the red dot because those fittings have been glued together. There are techniques for undoing the glue, but people seem to have varying levels of success with those techniques, most, from what I've seen here, fall into the "little to none" category. Instead, you'll have to cut the pipes off. This will require a small hacksaw or pipe cutter. In either case, be sure to make your cut nice and square to the pipe, or you may end up with leaks when you reassemble new pieces.

You would have to replace this plumbing all the way to where it screws into the grey Air Admittance Valve (AAV) (it does screw into that, doesn't it?), or, possibly, by cutting the short straight section that has the actual dot on it.

You'd then recreate this creative bit of plumbing, but make it a little shorter so that the inlet end is lower to match up with the outlet of your new trap.

You might be able to get away with cutting the vertical white pipe between the two grey pieces (AAV on top and "dump trap"?) on the bottom. Shortening that vertical white piece would allow you to move the whole assembly down to meet up with the new trap.

I'm not sure what, exactly, you mean when you say that the new trap has a "horizontal nozzle" since it seems to me the existing one has a horizontal exit, as do all the ones I've seen installed in my house or at the store. However, you have the pieces in hand, you'll have to do the fiddling to make it fit.

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  • That sounds perfect, thanks. The new trap has, in addition to the horizontal pipe coming off like the one in the picture, a second horizontal nozzle (that's the term the company, McAlpine, use) for receiving the waste pipe from a dishwasher. That nozzle means that the horizontal pipe has to be a bit lower and hence it doesn't fit onto the existing set up.
    – Tom
    Mar 9 at 23:57

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