Solvent weld to push fit adapter/connector

[Mr M]

The existing waste pipework from my bath and wash hand basin are all in solvent weld and need replacing. The bath is 40mm and the wash hand basin is 32mm. Both connect separately into the 110mm soil pipe via strap boss connectors. I would prefer to use push fit instead of solvent weld as I already have some 40mm and 32mm push fit fittings and pipe readily available.

If I leave the two solvent weld 90 degree bends in that are both cemented into the wall and chop the old solvent weld pipes leaving a couple of inches spare to connect the new onto, can I get a solvent weld to push fit straight coupler/adapter? Alternatively, would a compression coupler work connecting one side to my existing solvent weld pipe and the other side to my new push fit pipe?

 

[Madrab]

Why you would ever want to do that escapes me. Waste pipe should always be SW wherever possible.

Pushfit can cause so many problems for the next guy, who doesn't know there's push fit, then they use a pressure plunger to dislodge a blockage and blows a fitting off somewhere, usually where it'll cost a fortune to get to.

To answer your original Q tho, yes a compression coupler will fit both.

 

[Mr M]

Why you would ever want to do that escapes me.

As I mentioned, I already have some 40mm and 32mm push fit fittings and pipe readily available.

To answer your original Q tho, yes a compression coupler will fit both.

Thanks for confirming that.

 

[Mr M]

I've had another look at the pipework this morning. Initially, I may just swap the two strap boss connectors at this stage as they both have slight leaks on them and then change the remainder of the pipework at some point in the near future. How easy are boss strap connectors to fit?

I am assuming that the end of the pipe that goes through the existing boss strap connector and connects into the soil stack will poke into the inside of the soil stack slightly through the hole that was drilled into it, maybe by 10mm or so? I won't know this for sure until I get the old boss out but if it does poke into the inside the soil stack and bearing in mind that my pipework is solvent welded and cannot be temporarily disconnected like push fit could and that the other end of the pipe connects into a solvent welded bend that is cemented into the wall, how do I a) remove the old boss strap connector off the existing pipework without pulling the pipe out of the soil stack and b) get the new boss with its rubber adaptor, over the end of the existing solvent welded pipework, without pulling the pipe out of the soil stack?

Also, if the existing boss strap connectors have been solvent welded on, how do I remove them without damaging the soil stack?

 

[Madrab]

As I mentioned, I already have some 40mm and 32mm push fit fittings and pipe readily available

Not what I meant really. I appreciate there may be spare push fit available but TBH It's something that I'd never recommend to be used and would consign it to the recycling bin.

How easy are boss strap connectors to fit?

Easy enough really with the correct sized corer

I am assuming that the end of the pipe that goes through the existing boss strap connector and connects into the soil stack will poke into the inside of the soil stack slightly through the hole that was drilled into it, maybe by 10mm or so?

Not necessarily, depends on how the pipe's cut and also depends on the type of strap boss and connector, some have a stop inside. The boss itself only has a small lip

pipework is solvent welded and cannot be temporarily disconnected like push fit could

Can be cut and re-joined quite easily to remove and replace other fittings

 

[Mr M]

Can be cut and re-joined quite easily to remove and replace other fittings

So I may need to cut the pipwork a few inches away from the soil stack to allow the small section of existing pipework that's connected to the stack to be removed and to allow the boss to be fitted onto it and then reconnect the pipework using a straight connector. Is that correct?

Also, if the existing boss strap connectors have been solvent welded on, how do I remove them without damaging the soil stack?

 

[Madrab]

I presume the pipe runs into a strap boss at the moment? You say they are leaking, do they have rubber reducing bungs or do they have glued hard shelled push fit reducers?

Normally the boss adapters leak because the pipe into them isn't lined up or has the correct fall and the waste water then tracks back along the pipe. They can both be serviced, the former's seal can be replaced and the latter can just be swapped for a new one which will avoid having to replace the boss'

 

[Mr M]

I presume the pipe runs into a strap boss at the moment? You say they are leaking, do they have rubber reducing bungs or do they have glued hard shelled push fit reducers?
View attachment 350919 View attachment 350920
Normally the boss adapters leak because the pipe into them isn't lined up or has the correct fall and the waste water then tracks back along the pipe. They can both be serviced, the former's seal can be replaced and the latter can just be swapped for a new one which will avoid having to replace the boss'

Both run into a boss strap currently. The pipe connection from the wash hand basin looks similar to the grey one on the left image above. The other one from the bath has a screwed connection where the pipe joins into it and looks similar to the image below.



Neither seem to be leaking from the part where either of the pipes join the boss straps. Both appear to be leaking from where the inside face of the curved flange (shown on the above image) is fitted against the soil stack. The whole installation does look quite old and attempts do appear to have been made previosuly to patch them up but not by me, so the previous owner presumably had an issue with leaks and tried to seal them rather than replacing them with new.

I cannot see if either of the boss straps has a rubber bung in them.

If the curved flange on each boss strap has been solvent welded to the soil stack, how do I remove them without damaging the soil stack?