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

[Oxbow16]

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

 

 

 

Edited December 1, 2021 by Oxbow16

[ProDave]

A TRAP screws onto that fitting.  Have you tried finding a trap that fits?

 

You can't just join that to the 40mm waste pipe.

[Oxbow16]

Sorry, it's been a long day!  I meant trap, which to be fair does consist of bits of pipe   I've amended the title and thread to make it clearer though....  

 

Cheers

[ProDave]

So you find a trap that fits the sink, and then if the outlet diameter of the trap differs to the waste pipe you want to join to, you use the appropriate reducer, not one of those rubber things.

[markc]

A lot easier to remove the old one and replace.

[Oxbow16]

5 hours ago, ProDave said:

So you find a trap that fits the sink, and then if the outlet diameter of the trap differs to the waste pipe you want to join to, you use the appropriate reducer, not one of those rubber things.

 

That all sounds great, but to be honest that's why I'm here because I don't know what I would need.  Nor whether it even exists!

 

 

5 hours ago, markc said:

A lot easier to remove the old one and replace.

 

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.

 

 

You'll have to forgive me, I'm not familiar with the different types of plumbing fittings, BSP, etc. But having looked into it more it turns out that the "nut" from a standard trap (the bit that you tighten) actually screws on fine, so 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, is there anything other than the rubber reducer with jubilee clips that will work?

 

Many thanks

 

 

 

[markc]

@Oxbow16 if it is 1-1/2 bsp then this makes it much easier and I would leave it in place. Might be worth getting a couple of fittings and with a bit of fettling get a connection to work.

[Oxbow16]

Someone has recommended a McAlpine TF12A adapter, and judging by the pictures of it I think it could be just the job. I've got one on order and will report back as to whether it works.

 

Many thanks for the help

 

[Oxbow16]

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

 

 

 

[ProDave]

That will go into the top part of a telescopic P trap.

 

But sink and a half usually have a more versatile single trap with a tee connection to take both wastes into one trap and both halves are usually telescopic.

 

So buy a 1 1/2 inch telescopic P trap and swap the parts over, use that one with the fixed nut for your belfast sink, and the one that comes off the telescopic trap should go in the kitchen sink to replace the one you have borrowed.

 

Sometimes it can be handy to have a box full of assorted drain fittings to do a bit of mixing and matching.

[dpmiller]

if the rubber seal in that fitting sits in a recess, it may not seal to your dodgy looking waste.

[Oxbow16]

21 hours ago, ProDave said:

Sometimes it can be handy to have a box full of assorted drain fittings to do a bit of mixing and matching.

 

I'm definitely getting that feeling!

 

 

21 hours ago, dpmiller said:

if the rubber seal in that fitting sits in a recess

 

It does sit in a recess, so you may well be right.  I tried 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.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

 

 

 

 

 

 

 

[Oxbow16]

The plot thickens...! I haven't ruled out any of the above, 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!

 

 

 

 

[Oxbow16]

For the benefit of anyone coming across this in the future who finds themselves in a similar situation, my plan changed again! 

 

Someone recommended this:

 

https://www.wolseley.co.uk/product/mcalpine-t12-bsp-female-x-male-couplng-15-x-1-25/

 

I ended up getting one of those and did the following...  From the sink plug hole:

- 1 1/2" - 1 1/4" coupler reducer with flat washer, as per link
- 32mm telescopic P trap
- Connect to existing pipework (which is 32mm)

 

It's all working great.  

 

 

Thanks one and all for the help.  

[ProDave]

Thanks for posting that.  The old saying "every day is a school day" is so true, I had not seen that fitting before and it seems to have solved your issue, so duly filed away in memory for future use. (no guarantee I will be able to recall the memory when I need to though)

[Oxbow16]

My pleasure.  It makes a refreshing change to actually be able to offer something useful and not just come onto the forum looking for advice   

 

I think the McAlpine T12A-F bit would have been just as useful if I wanted to stick with 40mm the whole way.  I only switched to the other because the pipework was in 32mm and I didn't want to change it unless I had to.  

 

Cheers