Washing machine - sink - 32 /40mm

[Kmurphy]

I’m moving my kitchen sink and washing machine into my garage and routing the plumbing into the downstairs toilet. The downstairs toilet is due to be upgraded in several months time with the rest of the kitchen. I’m getting ahead of all that, so there’ll be a significant time gap.

It’s an external wall but an old house, so I assume single skin and I’m adding 50mm insulated drywall in the garage.

The kitchen sink trap is 40mm… and the washing machine attaches to that. The downstairs toilet sink waste is 32mm. 32mm waste run is less than 1m and goes into an adaptor and into the toilet soil pipe.

It’s pretty tight and awkward so major chances of any significant works only possible after removing the toilet and sink entirely.

I considered running 40-32 adaptor in the garage and plumbing into the rest of the 32mm. But, if there’s any sort of issue, drilling out the extra for 40mm pipe feels like a nightmare. Do people think 32mm all over is going to give me back flow?

Second option is 40mm pipe through the wall and reduce with an elbow or something inside the downstairs toilet (if I can physically do that) and leave the rest of 32mm. When I get the toilet done a pro can sort it all to 40mm. But am I going to cause back flow with even that 1m of 32mm setup?

If I am… I think I have only one other option. Make everything 40mm (adapt toilet sink if needed - can be messy as it’s getting replaced). But, I can’t find anything to plumb 40mm into a toilet soil pipe - any ideas?

 

[Kmurphy]

FWIW - this is where the 32mm goes into the toilet pipework. It’s in the corner behind the toilet. On the right is plasterboard. Even just to see what’s here means removing part of a wall. Changing this connection at all means uninstalling the toilet for sure

 

[foxhole]

You should be able to add to 32mm pipe , not ideal but should be ok , you can change in the future .

 

[Madrab]

If the sink is getting relatively high use, with sink loads of water being let go then along with the washing machine the 32mm will struggle. It'll act as a bottleneck and will slow the flow down. Worst case: it'll cause self syphoning, so fit an antivac trap on the sink. It's not a long term solution though and will need to be altered to 40mm sooner rather than later.

 

[Kmurphy]

@Madrab which sink or both?

If I did want to switch up everything to 40mm can anyone recommend something that allows me to plumb 40mm into the toilet outflow? I can’t seem to find anything

 

[Kmurphy]

McAlpine DC1-BL-BO Drain Connector with 1 1/2" Pipe Boss

Finned seal spigot for internal connection to 4"/110mm cast iron, plastic or clay • Ideal for low level connections • 1½" Universal Vent Boss • Include Blank Cap • Should only be fitted on ground floor due to a reduction in the internal outlet diameter of the boss pipe connector • Manufactured...

www.toolstation.com

This’ll work if I go the whole hog?

 

[Madrab]

Are you sure that's a 32mm boss, that would be a little unusual.

If it is then you would probably be easier cutting off that 32mm boss and then core and glue a 54mm strap boss into it. Then a reducer to take it to 40mm.

 

[Kmurphy]

On the current fitting - I get you. That might be the way to go

I made the mistake of whipping the plasterboard off the wall to have a peak. Whoever did the pipework to move the boiler from under the stairs into the garage clearly never thought anyone would do that. I was momentarily concerned about the structural integrity of my house and then popped the plasterboard back on...

 

[Madrab]

It's 1 1/2" so I think

if it's 1 1/2" (40mm) then what's the issue?

Apologies just trying to visualise - where is that elbow/boss and is the pipe on the other side of it 32mm and that is what you want to connect to??

 

[Kmurphy]

@Madrab - cross wires. My initial idea was to replace the soil/pan pipe with a new boss. But I think coring out and a strap for what might be a few months before a pro comes in and scrap everything is a great way to go

FloPlast Strap Boss Black 110mm - Screwfix

Order online at Screwfix.com. 110mm. Easy clip connection to soil pipe. Supplied with 32mm and 40mm push-fit boss adaptors. For use with boss adaptors to accommodate 32, 40 and 50mm waste pipes. FREE next day delivery available, free collection in 1 minute.

www.screwfix.com