What pipe is this and how do I join to it?

[GB]

I want to change the basin in the bathroom. It was installed 50 years ago, and the main problem I anticipate is joining up the new basin waste to the old waste.

The old waste is plastic, appears to be push fit, and has an outside diameter of approx 34mm. Any idea what sort of connector I am going to need, please?

Is this going to be excessively brittle and split if I try and cut it?

Unfortunately the waste goes vertically down from the basin, then disappears under the bathroom floor. If it splits, I'll have to run a new waste down the outside of the building.

[Harry Bloomfield Esq]

GB explained on 21/06/2022 :

34mm is a standard push-fit size. If the old fitting is well stuck on the pipe, just cut through the fitting (angle grinder/dremel), to avoid damaging the pipe.

[Colin Bignell]

Push fit for 32mm pipe, by the sounds of it. The 32mm dimension is the internal diameter, so the OD is about a couple of millimetres larger.

[Andy Burns]

McAlpine "multifit" provide a reasonable amount of accommodation for variations

[GB]

Thanks all. I'll give it a go.

My wife thinks I'm barmy, as I only want to change the basin so as to fit a mixer tap.

[Tim Lamb]

Bear in mind the possible low flow issues if your water is gravity fed.

[GB]

The cold is mains and the hot is gravity, so I was going to get something pretty simple, like this:

[John Rumm]

Sounds like standard push fit 1.25" (note solvent weld 1.25" is a different diameter!)

However, for easy, just buy a "universal" compression fitting - that will join to anything that is in the ballpark size.

More info here:

Probably not - push fit tends to be more "plastic" anyway.

[Tim Lamb]

Claims to be OK on low pressure!

There have been several threads in here where problems with gravity fed mixer taps have been discussed.

I have no direct experience to offer but would avoid small bore, flexible final couplings if possible.

[Andy Burns]

If you can find one where the hot and cold don't mix within the body of the tap, but stay in concentric pipes all the way to the end of the spout. You can certainly get tall kitchen taps like that, bathroom basin ones I'm struggling to see any.

[Roger Mills]

Yes, indeed. If they 'mix' within the body of the tap, forget it! The high pressure cold will stop the low pressure hot dead in its tracks - and may even reverse it. You would then have to operate the taps one at a time - which would defeat the purpose of having a mixer!

Beware of taps which claim to work on high or low pressure. By 'low pressure' they often mean low pressure mains at ~ 1 bar - not gravity feed at ~ 0.2 bar. I ended up having a mammoth dispute with Wickes over this very thing.

[Dave Plowman (News]

I have a mixer on the bathroom basin. Mains cold but gravity hot with the header tank not that much higher than the bathroom ceiling. The usual

10mm? tails into the mixer. Works just fine. You don't really need maximum flow and pressure possible for a basin.

[GB]

I expect that the cold mains can be tamed just by not turning the tap on too much. If I don't go for a dual flow tap, I had better install a check valve on the hot side. Did you bother?

[SteveW]

I just partially closed one of the isolation valves to get a rough match, as ours is a single lever operated tap, giving full hot to one side and full-cold the other.

It's not applicable for our. It's a open topped channel for a spout and the water mixes in the open, not within the tap body.