Kitchen Plumbing

jonnypetrie · 12 Sep 2020

Hi, I'm changing the sink waste plug and trap for my kitchen sink. I've purchased McAlpine appliance trap 40mm and a waste plug with 40mm thread.

I cant connect the female thread to the basin waste as the thread is approx 50mm. I've searched and not been able to find a sink waste plug larger than 40mm. Am I missing something?

I don't want to add any other parts on like reducers as I'm tight for levels to the outfall.

footprints · 12 Sep 2020

Most sinks these days have the strainer type waste, and fit standard traps no problem. https://www.victorianplumbing.co.uk...AC2wUHD0cA277iaRyMxoC6LoQAvD_BwE&gclsrc=aw.ds
Are you sure you do not have a basin waste, or a strange sized trap for commercial use.
Pop in to a DIY store and have a look at the fittings to see what has gone amiss.

jonnypetrie · 12 Sep 2020

I've got an old stainless steel sink that I'd like to keep, it doesn't have a large enough depression for the strainers. I'm live 1h drive from a DIY shop, so it's not easy to pop in. I've looked on Victoria plumb, and their kitchen wastes are still 40mm or 1 1/2". The trap I bought is for domestic, it's just with these plastic systems you have the 40mm pipe, then it fattens up where the joints so the thread dia is like 50mm or so.

just pumps · 12 Sep 2020

Would the McAlpine waste BT4 or ASE10 work?

dal5band · 12 Sep 2020

Generally there are two sizes of connector for sinks 11/4" (wash basins) and 11/2"(kitchen sink). The picture shows a trap with a 11/2" connector. This will have a standard thread for connecting to a 1 1/2" sink waste. Sounds as though you have an old sink with a smaller waste,or you have purchased a 1 1/4" waste ( the bit that fits the sink and has the plug). You need 1 1/2" waste. The pipe sizes are metri but the sink wase connectors use the old thread sizes.

jonnypetrie · 12 Sep 2020

Here's two pics showing the sizes I have. The female thread at the top of the Y branch is more like 1 3/4

jonnypetrie · 12 Sep 2020

This is what I've bought

https://www.screwfix.com/p/mcalpine...EALw_wcB#product_additional_details_container

Alec_t · 12 Sep 2020

From your pics it looks like the plastic female thread (not the outer wall) is ~4cm diam and the metal male thread is the same?

jonnypetrie · 12 Sep 2020

The plastic female thread is more like 45mm

jonnypetrie · 12 Sep 2020

jonnypetrie · 12 Sep 2020

Okay, figured it out. The sink waste I bought was advertised as 40mm, but I now gather it's actually 1 1/4" BSP, which actually measures 1 1/2". What I need is the 1 1/2" BSP which actually measures 1 3/4". I should have known it was not as simple as buying a 40mm trap and a 40mm sink waste

JimCrow · 12 Sep 2020

1 1/2" BSP = 47.8mm Ø, 1 1/4" BSP = 41.9mm Ø
If you're struggling for fall, you can gain about 25mm in the outlet height by cutting the adjustable tube that's inside the trap body.

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