Washing machine waste problem

[Tapender]

Hi, new to the site and looking for some advice. The waste pipes from both my washing machine and dishwasher feed into a 40mm standpipe which is connected to the waste pipe under the kitchen sink. The dishwasher works without any problems but when the washing machine starts to empty the water is coming back up and out of the standpipe. This problem only arose when I changed to a new washing machine which makes me thinks it is pumping out waste water faster than the old machine.
I have an unused washing machine waste connection under the sink and was thinking that the solution might be to get an extension for the waste pipe from the washing machine and connect it directly under the sink.
As I am completely inexperienced in this area I would be very grateful for any advice. Thanks.

 

[Burnerman]

Hi and most welcome!
It's curious that the standpipe can't cope with the washer......is the discharge hose pushed too far in?
Sometimes it's not a good idea to run both machines at the same time.
Is the drainage from the standpipe clear?
You can connect an extended drain hose to under the sink, but it's route will need to rise to the top of the appliance, and then gently slope down to the sink connection, if you can manage it.
John

 

[Tapender]

Hi John, thanks for getting back to me. The discharge hose only reaches 4 to 5 inches into the standpipe ( basically as much as is allowed by the curved plastic bracket that came with the washer) and the dishwasher is the same. We never run both machines at the same time.
I used what I think is called a plumbers snake to check the pipes and they seem to be clear. However the the piping has been installed underneath kitchen cabinets and is almost impossible to get at without taking the kitchen apart. The piping initially runs at a slight downward slope for about 6 feet from the stand pipe but then turns a corner and actually rises about 4 to 5 inches over about 5 feet before the final connection to the drain. Could this be part of the problem? Also the bottom of the standpipe does not actually have the u-bend water trap I have seen on other fittings. It has a sort of cobbled together u-bend made up of right angle joints and a small length of pipe. Do you think this may be restricting the flow of the waste water?
Finally the waste water connection under the sink will only allow the waste pipe to run down by about 4 inches over approx 10 feet. Do you think that will be sufficient.
I would be grateful for any advice on this. Ged

 

[Burnerman]

With a standpipe system Ged, the top of the vertical pipe is usually level with the top of the machine, so the waste water gets a bit of help by gravity. However, a 40mm pipe should handle this with little difficulty - providing it isnt blocked!
I dont like the idea of the waste running uphill a bit either.....this will be full of water which will be a restriction to some degree.
The U bend sounds a bit cobbled up, but shouldn't really matter.
Try running a hose(carefully) down the standpipe to see what it can handle?
The fall to your sink connection is enough, because the machine waste is pumped....the worse scenario is that some water may appear in the sink, but I'd doubt that.
John