Belfast sink - joining old waste to new 40mm trap and pipe

[Plumb Line]

Hi all

We're having an old belfast sink fitted in our WC/utility room. We'd like to use the existing old waste; and by all accounts it'd be a pig's jacksie to remove even if we wanted to!

The threaded section in the photo measures approx. 1.88" / 47.8mm outside diameter and 1.24" / 31.5mm internal diameter.

The only thing I can think to use is something like this:

Swell Rubber Reducer

Rubber reducers for many pipe grades like PVC, waste and pressure pipes Made from a high grade EPDM rubber Various sizes available

www.swelluk.com

But whilst the sink out will be inside the reducer, which is good from a gravity point of view, the 40mm trap and pipe will also be inside the reducer which ain't so great.

So I wondered if there are any other options? Anything entirely different? Or something along the lines of the rubber reducer, but with a threaded connection on the smaller end to it connects to the 40mm trap and pipe properly?

I'll keep looking in the meantime.

Thanks a million

 

[rpm]

Cut it out before the sink is fitted and replace with the McAlpine Belfast sink waste.

 

[Basher]

That waste o/d is surely 1.5" bsp?
So a 1.5" trap would fit directly.
But it sounds like you already have a 40mm trap.

There are reducers of various sorts, eg

1.1/2 inch BSP to 1.1/4 inch BSP Thread Reducer - 39004012

1.1/2 inch BSP to 1.1/4 inch BSP Thread Reducer This plastic threaded reducer will reduce male 1.1/2 inch BSP threads to a 1.1/4 inch BSP male

www.plumbers-mate-sales.co.uk

 

[Plumb Line]

Cut it out before the sink is fitted and replace with the McAlpine Belfast sink waste.

Perhaps. And if we have to do that then so be it, but I'd like to see what options I have first as it's definitely our preference to keep the old waste.

That waste o/d is surely 1.5" bsp?
So a 1.5" trap would fit directly.
But it sounds like you already have a 40mm trap.

There are reducers of various sorts, eg

You'll have to forgive me, I'm not familiar with the different types of plumbing fittings, BSP, etc. Turns out that the "nut" from a standard trap (the bit that you tighten) does indeed screw on fine, so yes, I guess the thread is standard 1 1/2" BSP.

The problem is with the pipe section and rubber seal of the trap. Because the sink waste's inner diameter is smaller than normal, the trap pipe won't slot into the waste to form a seal with the O ring. So whereas it should be like this:




On my sink it doesn't and it looks like this:




With all that in mind, do you still think I should be able to get something to work?

Many thanks

 

[exedon2]

Look for Mcalpine 1 1/2 waste adaptor used on commercial sinks which have flat bottomed wastes can then use standard trap.

 

[ShaunCorbs]

https://www.NoLinkingToThis/p/mcalpine-t12a-f-1-bsp-eu-uk-coupler-white-40mm-x-40mm/1358v

That’s what you need

 

[Basher]

https://www.NoLinkingToThis/p/mcalpine-t12a-f-1-bsp-eu-uk-coupler-white-40mm-x-40mm/1358v

That’s what you need

On that part the female thread is 40mm metric, not 1.5" bsp, so I thought it wouldn't fit?

 

[ShaunCorbs]

On that part the female thread is 40mm metric, not 1.5" bsp, so I thought it wouldn't fit?

Trap nut fits so that will aswell

 

[Plumb Line]

Looks like the McAlpine could be just the job, judging by the pictures. I've got one on order and will report back as to whether it works.

Many thanks for the help and recommendation.

 

[Plumb Line]

I'm unable to leave the house at the moment, so haven't picked up a McAlpine T12A-F as of yet.

But I was mulling it over just now and took the waste pipes off my kitchen sink to see what they have. Turns out that what I have on the 1/2 side of my one and a half sink is just the ticket... Or at least I think it is, but I'm no expert. It has a moulded "nut"/end and flat washer. I've put a couple of pics below.

Is there any reason why something like that wouldn't work? If it is ok to use, then:

• What's it called / how do I find one the same?
• How does it then connect to the P-trap?

Sorry that these are such basic questions, and also if I'm missing the glaringly obvious. It's all new to me!

Cheers

 

[ShaunCorbs]

Won’t fit as the Belfast sink is flat faced

 

[Basher]

As per Shaun
Would only seal if you could fit additional washer(s) so that ring of plastic didn't touch the flat face of the belfast waste.
It's the same fundamental problem you raised originally, only a recessed washer instead of an o-ring!

And my tongue-in-cheek suggestion above is a bodge

 

[Plumb Line]

Aha, I didn't think of that and really appreciate you guys pointing it out. Thank you. I did try it with a bucket beneath and all seemed well, perhaps because gravity is on its side. But I think it is worth doing once and properly so I'll stick with using the McAlpine T12A-F.

Once I've got that, I'm wondering what the best way would be to connect to my existing pipework. In the correct order from the plug hole, I'm thinking:

1. The McAlpine T12A-F
2. A telescopic P trap, as there's a shortfall in the height.
3. Cut the end of the existing pipework (the horizontal bit on the solvent weld section) to whatever's needed to get the correct position under the sink's waste.

Does that all sound good?

One problem though... The sink waste is 1 1/2"/40mm. The existing pipework is 32mm. Where would be the best place to use a reducer and what type of reducer? The plumber left a reducer piece here, but I can't for the life of me see how to use it properly for a good seal. And I'm not certain if it's the best solution or not... I was wondering about one of these:

https://www.NoLinkingToThis/p/mcalpine-st28m-straight-connector-white-32mm-x-40mm/95260

And perhaps if that can go directly after the T12A-F? Then I can use a 32mm trap instead (the one the plumber left is 40mm) and may not even need the adjustable trap if the reducer drops me to the correct height.

That's just me thinking aloud though and not really knowing anything! So any thoughts from the experts are most welcome please. Pics below to help make sense of my gibberish. But happy to take more as needed.

Cheers

 

[ShaunCorbs]

telescopic p trap should work

 

[Plumb Line]

Great, that's good to hear, although I'm still unclear as to where the best place is to reduce.

But the plot thickens...! I haven't ruled out any of the above potential plans, but I am also wondering whether I should just start again with new everything from the toilet itself.

I'm still struggling to get my head around sizes and compatibility. I've removed the bend where it fits to the toilet - see the photo below. The outer threaded section of the piece in the photo measures around 47.5mm, the outer section above the threaded part (i.e. right at the lip) is around 45mm, and the inner diameter is 41.8mm. So what size is that piece compatible with? If it's compatible with 40mm wastes/pipes/fittings, then I might start afresh from there and no reducer will be necessary anywhere. At least I don't think it will! Obviously everything will be a bit chunkier but hey ho, at least it will be right.

Thanks to anyone who's sticking with me through this and sorry for making something complicated out of something which is probably very simply for those who know!

 

[ShaunCorbs]

Picture of the pan from the right hand side please

 

[Plumb Line]

Picture of the pan from the right hand side please

Sure thing. Is this what you mean:



Many thanks

 

[ShaunCorbs]

90° Bend Adjustable Length Extended Inlet Rigid WC Connector | McAlpine Plumbing

Achieve a perfect fit with the 90° Bend Adjustable Length Extended Inlet Rigid WC Connector, ensuring flexibility for various toilet installations.

mcalpineplumbing.com

Boss Pipe for use with WC Connectors | McAlpine Plumbing

Achieve versatile connections with the Boss Pipe, designed for use with WC Connectors for efficient plumbing installations.

mcalpineplumbing.com

 

[Plumb Line]

Thank you for the links. Is that to say the existing WC connectors are no good and/or the wrong size? I would rather not replace them unless it is necessary to be honest.

Is the "1½" Universal Vent Boss" on the second link likely to be a different size to the one on my existing WC connector?

Thanks again for your help

 

[ShaunCorbs]

Correct

Your current one is for an 11/4 connection you won’t get an adapter to 11/2

 

[Basher]

The sink waste is 1 1/2"/40mm. The existing pipework is 32mm. Where would be the best place to use a reducer and what type of reducer?

Just to say that if you do go the 32mm route, putting this on the belfast sink instead of the T12A-F, solves that reduction issue:

BSP Coupling Waste Reducer - 1.5 inch

Medical, dental & commercial handwash taps & sinks including HTM64 taps & sinks. Tap spares & replacement parts for repairing most taps. Bathroom, kitchen & shower taps & accessories

www.notjusttaps.co.uk

 

[Plumb Line]

Just to say that if you do go the 32mm route, putting this on the belfast sink instead of the T12A-F, solves that reduction issue:

BSP Coupling Waste Reducer - 1.5 inch

Medical, dental & commercial handwash taps & sinks including HTM64 taps & sinks. Tap spares & replacement parts for repairing most taps. Bathroom, kitchen & shower taps & accessories

www.notjusttaps.co.uk

Good find! So that would solve both problems in one small piece - i.e. a flat wide washer for my awkwardly shaped waste, and a reduction to 32mm at the same time. In which case from there I'd need a 32mm telescopic P trap and that's it? Might just need to cut the existing pipe back a little if it sticks out too far for the P trap?

Seems a solution is hopefully coming together.

Shame my plumber couldn't have recommended any of this!

 

[ShaunCorbs]

Depends on what your planning on running the sink as will take a bit to drain in 32mm and glug abit

 

[Basher]

Depends on what your planning on running the sink as will take a bit to drain in 32mm and glug abit

I take the point, but the centre aperture in the original belfast waste fitting being used is much smaller than normal, probably around the 30mm mark, so that will throttle the flow as well!

 

[Plumb Line]

Depends on what your planning on running the sink as will take a bit to drain in 32mm and glug abit

The plan would be, from the sink plug hole:

• 1 1/2" - 1 1/4" coupler reducer with flat washer, as suggested by @Basher
• 32mm telescopic P trap
• Connect to existing pipework (which is 32mm) from there, as seen in this photo:

Is that likely to cause slow drain / glugging?

If using 40mm to prevent the slow drain / glugging, would everything have to be 40mm? Or would a 40mm trap going into the existing 32mm pipework be enough?

Cheers

EDIT:

I take the point, but the centre aperture in the original belfast waste fitting being used is much smaller than normal, probably around the 30mm mark, so that will throttle the flow as well!

I've just measured it and it's 34mm, so you weren't far off With that in mind, will 32 vs 40mm trap and pipes make much difference then?

 

[ShaunCorbs]

You’ve got nothing to loose other than a p trap and an adapter

 

[Plumb Line]

For the benefit of anyone coming across this in the future who finds themselves in a similar situation, my plan (as outlined in post #25) worked a treat, and I'm set up and all works perfectly.

Thanks one and all for the great help. I wouldn't have got there without you!