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

[Krome10]

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:

https://www.swelluk.com/swell-rubber-reducer/
But whilst the sink out will be inside the reducer, which is good from a gravity point of view, the 40mm trap/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/pipe properly?

I'll keep looking in the meantime.

Thanks a million

 

[sawdustandwax]

the rubber reducer will be fine with some sealant, if you want to add an internal part as well so the waste goes straight into the, well the waste pipe and doesn't sit in the reducer, look at rubber funnels. Don't do a google image though.. I'm off to wash my mouth out after seeing one image....

 

[Krome10]

Don't do a google image though.. I'm off to wash my mouth out after seeing one image....

Needless to say that's the first thing I did I couldn't quite figure out what this is all about and don't intend to find out!

 

[Phill05]

47.8 is the equivalent of 1 1/2 BSP (british std pipe thread) what you would have on the Belfast and can be found here:
https://www.stevensonplumbing.co.uk/bspt.html

 

[Krome10]

Thanks @Phill05 - that's a very handy table and explanation generally. I do struggle a bit with pipe sizes etc and that goes a long way to helping.

So - armed with that knowledge - should I be looking for a 1 1/2 Inch BSP to 40mm coupler?

Cheers

 

[Phill05]

Yes look under plumbing on the site look for traps / sink wastes and it is there with a 40mm outlet for push fit or glue.
https://www.stevensonplumbing.co.uk/kitchen-sink-p-trap-40mm.html

 

[Krome10]

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. Sorry for being so slow off the mark with realising that! Plumbing fittings are not my forte.

Having looked at it a bit closer, 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

 

[Fergie 307]

Is there enough meat on it to just bore the inside to fit. Only going to be brass, you could do it on a wood lathe. Or turn down the plastic.

 

[Phill05]

If you cut off the piece of pipe that goes up into brass so it is level and flat then put on a larger rubber washer then when you tighten up it covers the bottom of the brass fitting and some of the rubber squishes into the brass and makes a good seal.

 

[flying haggis]

from my experience different trap manufacturers make the bit that goes into the sink part differently so a different trap may be required. if you have a b&q nearby pop in and compare them or a decent builders merchants etc
ie this one looks to have a straight sided part to the spigot that goes inside the sink part
https://www.toolstation.com/shallow-bottle-trap/p20705

 

[Krome10]

Many thanks for the suggestions. I think I've found what I need... Someone recommended a McAlpine TF12A adapter, and judging by the pictures of it I think it could be just the job as it is designed with a flat washer. I've got one on order and will report back as to whether it works.

https://mcalpineplumbing.com/plasti...ings/s12a-fc-european-uk-waste-outlet-adaptor
Many thanks for the help

 

[Krome10]

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

 

[1steven]

Cut the old one off with a hacksaw and then replace it with a belfast sink waste fitting for under £10 on eBay have done it myself this year. Yes I am a plumber.
Belfast Butler Sink Waste For Weir Overflow Style Sinks + Chrome Plug BSW6CP2H

 

[Krome10]

Cut the old one off with a hacksaw and then replace it with a belfast sink waste fitting for under £10 on eBay have done it myself this year. Yes I am a plumber.
Belfast Butler Sink Waste For Weir Overflow Style Sinks + Chrome Plug BSW6CP2H

Thanks for the suggestion and I can see why it is a sensible one. But I really love the original waste and would much rather use that if at all possible.

An update on the above though.... I've since learnt that the piece from the kitchen sink would not be suitable because the washer/seal is in a recess and not flat and wide like the one in the McAlpine T12A-F. So it's back to using the McAlpine.

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.screwfix.com/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

 

[1steven]

Golden rule is you never reduce the pipe work size, you always step up never down. the more fittings you have the more potential leaks. Can you not replace the pipe work with new?

 

[Spectric]

When I fitted a new Belfast into the utility room I did not use a trap on the sink waste but a running trap in the pipework and all was fine, gave more room under the sink. Plumbing fittings are good because there are so few and BSP is not hard to get to grips with.

 

[Krome10]

Golden rule is you never reduce the pipe work size, you always step up never down. the more fittings you have the more potential leaks. Can you not replace the pipe work with new?

The problem is - I think - that the waste pipe connects to the top of the toilet soil pipe, and that connection is 32mm. So the reduction has to happen at some point unless I change the toilet pipe. And I'd rather not go that far if possible.

What's the downside of reducing from 40mm to 32mm somewhere along the line? Potential leak spots?

When I fitted a new Belfast into the utility room I did not use a trap on the sink waste but a running trap in the pipework and all was fine, gave more room under the sink.

More room would be a massive bonus. I don't suppose you'd be able to post a pic of what you have so I can see it in the flesh/plastic? Perhaps it'll give me a new option to consider....

Cheers

 

[Spectric]

Hi all I used was Cap and Lining and this screws straight onto the waste, short piece of pipe to connect to a 45 degree and out of the cupboard space, along wall into the running trap TR10 Running Tubular Swivel 'P' Trap and away. Your problem is going to be the 32mm pipe, going from a larger 40mm pipe to a smaller one can allow crud to build up and block the pipe, much better to either maintain the pipe size or go larger if the run is long.

 

[flying haggis]

from the pics it looks like the best way would be

1. The McAlpine T12A-F
2. A telescopic P trap, as there's a shortfall in the height.
3, short piece of 40mm pipe onto
4. reducer onto stub of pipe from existing pipework

with the reducer close to the sink at least if it blocks you can take the trap and reducer off in one to clean it all out

 

[Krome10]

I've got to say, this is all pretty impressive advice for a woodworking forum!

@Spectric - thanks for explaining and sharing. I've discussed that option with my partner and it's out on aesthetics as the trap would look quite odd and misplaced on the main pipe run.

If you can see the first photo in post 14 it shows the run from the sink to where it connects to the toilet pipe. I've just measured the straight run and it's 80cm.

Thanks @flying haggis (Norfolk ey, my old stomping ground). That sounds like the kind of thing I had in mind.

But the plot thickens...! I haven't ruled out any of the above potential plans, but I am also wondering whether I should follow @1steven 's advice and 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!