Solvent Weld to Pushfit Waste

[Andrew]

I have a run of solvent weld waste which needs to connect into a soil stack fitted with a pushfit boss.

McAlpine do a Pushfit to Solvent Weld adapter:

but it is the wrong way around.

Does anyone know of an adapter that has a solvent weld socket at one end (that a piece of pipe can be welded into) and what is effectively a short length of pushfit (i.e. slightly smaller diameter) pipe the other? Ideally 50mm although 40mm would do.

Andrew

[Tricky Dicky]

When connecting push fit to solvent weld most use this McAlpine fitting or you can use the 90 deg version.

You will have to fit a length of solvent weld into the boss on the stack and push fit from the fitting onwards. The only downside being you will need a length of both types of pipe.

Richard

[Andy Burns]

or the straight universal one?

[John Rumm]

Just use a normal "universal" (i.e. compression) fitting to transition - they fit both the nominal "40mm" solvent weld and push fit pipe sizes.

[Andrew]

This was the solution that I was trying to avoid. It is an additional compression fitting and then a reducer (enlarger) to get the 40mm pipe into the 50mm boss.

If there was one with a solvent fitting I could weld a reducer like this

directly inside it and reduce the overall chance of leaks in inaccessible spaces.

But if such a beast is not available then it is probably the only way.

[John Rumm]

Can you not change the boss on the soil pipe? Pushfit bosses are typically just rubber adaptors that push into the socket on the stack:

So swap it for a different size, or better still just use a solvent weld boss. Then:

[Andrew]

Thanks.

That first one looked ideal and should take solvent weld pipe so I could do my pipe run with solvent weld instead of compression fittings.

However, having got hold of one it has an outside diameter of 63mm which, although dimensions are hard to find, I think is for a stap-on boss. No idea why they are different sizes.

Unless I can find one that fits a 50mm boss then it is going to be back to plan A and use compression pipe throughout.

the soil pipe is already installed and I would rather not solvent-weld to it in case of access problems in the future.

[Tricky Dicky]

Flomasta do rubber bungs that fit push fit pipe to the boss they also do a solvent weld bush for the boss both available in 40 & 32 and I believe in

50mm.

Only problem is Screwfix who are supposed to be the main supplier does not always hold full stock, I have found the rubber bungs on SF website but could only find the solvent weld type on Amazon. I will try to get the relevant part numbers if you need them.

[Tricky Dicky]

CORRECTION

For Flomasta read Floplast the product codes for solvent weld bushes to fit the strap on boss are 32mm = SP20, 40mm = SP21 and 50mm = SP22

[Andrew]

Thanks. I saw those but according to one of the Screwfix reviews of the rubber adapters:

"Bought to fit into an existing boss in a branch fitting, however the adaptor was too large; adaptor was 60mm and boss in branch was 50mm.

Fitting size is fine for boss strap, which does come with both 32mm and

40mm adaptors anyway."

So sounds like the same as the one I already have. I can't believe it is so hard to find one that fits the normal 50mm boss. It would be ideal for what I am trying to do.

[Andrew]

In my house the 87.5 'horizontal' to vertical toilet connector has a couple of dummy side stubs just below the main sewer connector (?osma) and the original builder or plumber core drilled into these and solvent welded a 40mm and 50mm boss into these tappings. These bosses (?osma again) have epdm gaskets so that the final connection of the grey abs solvent welded pipes from sink and bath is just pushed into them and allows 'easy' removal should that be needed.

Those McAlpine adapters look as though they are intended to be solvent welded into a dummy boss that are usually in pairs each side of the 87.5 connector. Then you insert your final section of push fit into it.

What is actually fitted to your stack at the moment ?.

This is the type of osma connector I have in my house

[Andrew]

Pretty much the same as you have but, I think Marley rather than Osma. There is then, as you describe, a boss that can be solvent welded into the boss on the soil pipe which has a rubber gasket. However, this only takes push-fit pipe, not solvent weld. I had hoped to make up the rest of the run in solvent weld (which will go into the compression fitting on the trap) bit it is the connection to the stack which is proving problematic.