Washing machine and dishwasher waste

shiraz99

Can you buy a washing machine standpipe waste that also comes with a connection for a dishwasher or do you need to make one up yourself using something like https://www.screwfix.com/p/mcalpine-wm15-appliance-trap-white-40mm/5849v and a piece of 40mm pipe?

Also what's the difference between a 40mm push-fit pipe and solvent weld pipe, aren't they just both 40mm propylene pipes? Ignore this bit, just checked and they're different materials.

shiraz99

Or maybe https://www.screwfix.com/p/floplast-washing-machine-trap-white-40mm/18640 and https://www.screwfix.com/p/mcalpine-v33s-compression-domestic-appliance-tee-piece-connector-white-40mm/4167p would be better/cheaper?

alleycat`

shiraz99 said:

Also what's the difference between a 40mm push-fit pipe and solvent weld pipe, aren't they just both 40mm propylene pipes?

Not they're not the same.

One of those awesome "plumbing" things you learn the hard way about.

I understand why plumbers use solvent weld but it's a totally ^&*^%^ for DIYers when stuff needs modifying as a "one off".

grumbler

The first one isn't a 'standpipe' and is just for one appliance. It's an addition to your sink trap. For two appliances you need

 

See yourself, what's cheaper, but a standpipe requires a dedicated branch of the waste pipe.

To connect two appliance to a standpipe you'll need something like this

Solvent-weld waste pipes require solvent-based cement for assembling. Push-fiit ones give you more flexibility for adjustments in the future. The pipes can be different even if the nominal diameter is the same.

shiraz99

grumbler said:

The first one isn't a 'standpipe' and is just for one appliance. It's and addition to your sink trap. For two appliances you need

 

See yourself, what's cheaper, but a standpipe requires a dedicated branch of the waste pipe.

To connect two appliance to a standpipe you'll need something like this

Solvent-weld waste pipes require solvent-based cement for assembling. Push-fiit ones give you more flexibility for adjustments in the future. The pipes can be different even if the nominal diameter is the same.

I know the first one wasn't a standpipe which is why I asked whether I could turn it into a standpipe by adding some 40mm pipe at the top, cut to size. My other thought was getting a standard standpipe and installing the washing machine waste as normal from the top and fitting the tee-piece connector at the bottom of the pipe for the dishwasher (or fit the connector you pictured at the top of the standpipe) 😀

To confirm, the appliances do have a dedicated waste as they're quite far from the sink waste but at the moment they currently connected (jerry-rigged) via a loose T piece and and then into the waste, which isn't an ideal situation. It's not my property btw.

chrisw

shiraz99 said:

grumbler said:

The first one isn't a 'standpipe' and is just for one appliance. It's and addition to your sink trap. For two appliances you need

 

See yourself, what's cheaper, but a standpipe requires a dedicated branch of the waste pipe.

To connect two appliance to a standpipe you'll need something like this

Solvent-weld waste pipes require solvent-based cement for assembling. Push-fiit ones give you more flexibility for adjustments in the future. The pipes can be different even if the nominal diameter is the same.

I know the first one wasn't a standpipe which is why I asked whether I could turn it into a standpipe by adding some 40mm pipe at the top, cut to size. My other thought was getting a standard standpipe and installing the washing machine waste as normal from the top and fitting the tee-piece connector at the bottom of the pipe for the dishwasher (or fit the connector you pictured at the top of the standpipe) 😀

This is how mine are set up. The washing machine hose just loops over into the top of the standpipe whilst the dishwasher connects to a t-piece connector, although mine's half way up the standpipe rather than at the bottom of the pipe.

Rodders53

Push fit and solvent weld are ever so slightly different diameters: 

"40mm push-fit pipe has a 40-41mm external diameter but a 40mm solvent pipe has a 43mm external diameter." 

Google tells me.  So you can't mix and match pipes/connectors.  That's why they have the screw/tapered seal connections that cope with both outside diameters.

Washing m/c and dishwasher both have high flow rate pump outs and would ideally have their own standpipe drain and U-bend to ensure no possibility of unwanted back or over flow.  An air break/ Air entry is needed for drainage and it appears that the McAlpine twin connector has one  https://www.toolstation.com/mcalpine-standpipe-twin-connector/p46717  which seems a neat addition to a regular washing machine standpipe waste trap assembly.  (Albeit I'd have some reservations if both machines were in simultaneous use).

Slinky

Rodders53 said:

Washing m/c and dishwasher both have high flow rate pump outs and would ideally have their own standpipe drain and U-bend to ensure no possibility of unwanted back or over flow.  An air break/ Air entry is needed for drainage and it appears that the McAlpine twin connector has one  https://www.toolstation.com/mcalpine-standpipe-twin-connector/p46717  which seems a neat addition to a regular washing machine standpipe waste trap assembly.  (Albeit I'd have some reservations if both machines were in simultaneous use).

Our washing machine and dishwasher are on this setup, and we try to avoid running them at the same time as we're not convinced of the safety of doing so.

Section62

Rodders53 said:

An air break/ Air entry is needed for drainage and it appears that the McAlpine twin connector has one  https://www.toolstation.com/mcalpine-standpipe-twin-connector/p46717  which seems a neat addition to a regular washing machine standpipe waste trap assembly.  (Albeit I'd have some reservations if both machines were in simultaneous use).

We had a poster recently who had one of these, and the air vent hole became a very effective fountain/pressure washer when the downstream drain became partially blocked.

Personally I think I'd give the idea a miss and stick with something more traditional.