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

[DIYNotIan]

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

 

[just pumps]

Know you dont want to but I would slice the old waste and replace before the sink is fitted.
https://mcalpineplumbing.com/waste-...wastes/bsw6cp2h-centre-pin-belfast-sink-waste

 

[DIYNotIan]

Many thanks for the reply. 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

 

[just pumps]

Yes it is 1 1/2 BSP. Is the waste nice and clean where the pipe goes inside the sink waste (as per photo 2)

 

[Exedon]

If you really want to keep waste you need a Mcalpine T12A-F 1 1/2 flat washered connection to waste then a standard trap will fit

 

[just pumps]

If you really want to keep waste you need a Mcalpine T12A-F 1 1/2 flat washered connection to waste then a standard trap will fit

Isnt that an EU-UK thread converter.

 

[Exedon]

Used on commercial sinks to use standard traps

 

[Madrab]

You can change the type of trap you are using. It's not ideal as the McAlpine are as good as you get IMO but you want to find one with a flat mating face and not a spigot type that fits up inside the waste. I think Floplast may have a flat face, I know others do.

The TF12A adapter is a 11/4" to 11/4" as the sizes are closer so it may work, thread dependent, the SF12A adapter is the 32mm to 11/4" metric to imperial, as there is a bigger disparity in size. Bit like pipe changes - 15mm>1/2" (no converter needed) against a 22mm>3/4" (converter needed)

 

[DIYNotIan]

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.

 

[Nige F]

That sink is sitting on 2 basin brackets should be on sink brackets with legs.

 

[DIYNotIan]

That sink is sitting on 2 basin brackets should be on sink brackets with legs.

Well spotted! They're rock solid though and I feel the sink is safe. For belts and braces though we'll be adding some sealant between the back of the sink and the wall. Also, it's a baby belfast so not as heavy as the big version...

 

[DIYNotIan]

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

 

[Hugh Jaleak]

Could get a Telescopic trap, remove the supplied end and replace with that piece, ensuring all seals are in place as required. Only then you are essentially buying 2 traps, to make one and are left with a pile of useless pieces!

 

[DIYNotIan]

Thanks @Hugh Jaleak . But I've since learnt that the piece above 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 (good call on that), 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

 

[DIYNotIan]

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!