Washing machine waste planning

[di-why]

Hi all

Hope everyone is staying safe in these bizarre times! I was hoping to get some advice from the experts on waste pipes for a washing machine. I'm not a plumber, but I think I'm reasonably able when it comes to DIY.

I'd like to move my washing machine from the kitchen into a hall cupboard in my first floor flat. My current plan is to install a standpipe on the left wall of the cupboard and run it through the stud wall at the back of the cupboard to join the vertical 40mm waste pipe from the ensuite sink (approx. 18 inches distance). I've crudely drawn this onto the photos.

I've had a look through the forums and came across this thread which describes a potential issue - if the sink is discharging at the same time as the washing machine would the water be likely to back up and overflow the standpipe? The other concern I had is that when waste is discharging from the sink could it create a suction effect and draw water from the standpipe trap?

Unfortunately I can't easily access the soil stack to add a separate waste for the washing machine, so it would need to connect to an existing pipe. I suppose an alternative solution might be to run the washing machine hose through the wall and connect it to an appliance trap directly under the sink - this is how it's connected in the kitchen and makes a bit of a racket when it's draining so ideally I'd avoid this if possible.

I hope this all makes sense - any advice would be greatly appreciated!

 

[Aquarius]

If it is only 18”, then why not just drill a hole throughout wall and cupboard and join in there using a washing machine trap?

 

[di-why]

If it is only 18”, then why not just drill a hole throughout wall and cupboard and join in there using a washing machine trap?

Thanks for the reply! Do you mean take the hose directly through the wall and connect it under the sink using one of these?

It's definitely an option, that's how it's currently connected in the kitchen - it makes a bit of a racket in the sink plughole when it's draining though and I thought using a standpipe in the cupboard might make it less noisy.

 

[Aquarius]

Thanks for the reply! Do you mean take the hose directly through the wall and connect it under the sink using one of these?

It's definitely an option, that's how it's currently connected in the kitchen - it makes a bit of a racket in the sink plughole when it's draining though and I thought using a standpipe in the cupboard might make it less noisy.

Yes that’s what I meant. You could try a stand pipe, or perhaps tee into the wastepipe and use a hepvo valve?

 

[di-why]

Yes that’s what I meant. You could try a stand pipe, or perhaps tee into the wastepipe and use a hepvo valve?

Am I right in thinking I would need to add an air admittance valve if I'm teeing into the sink waste pipe, to prevent water being sucked out of the sink trap when the washing machine is discharging?

A hepvo valve might be a neat solution!