Stand alone washing machine drainage

[askman]

I'm going to be buying a new kitchen within which the washing machine will be isolated from the sink / dishwasher and will need it's own drain.

I'm proposing to run this in the floor, directly into the foul waste, however am unclear about the requirements of the trap.

I've had a look at the installation booklets from a couple of washing machines, and they all detail running into a shared waste with a sink and therefore state heights in line with the sink (i.e. running it above the level of the overflow, presumably to prevent backflow into the machine).

If I am running directly into the floor, is it suitable to run a 40mm waste pipe out of the floor with an S trap, and vertically up as high as I can go beneath the work top and loop the hose from the machine into this?

Surely if it backflows by doing this, I've got much bigger problems than a buggered washing machine...

Is there any need to sit the trap at a certain height off the floor?

 

[baldykev]

Will this help. https://www.screwfix.com/p/floplast-washing-machine-trap-white-40mm/18640

 

[Hugh Jaleak]

When connecting to a sink trap, the outlet hose needs to loop up above sink outlet level to prevent backflow from the sink into the machine. If discharging into a standpipe then as long as the end of the outlet hose is above the height of the top of the machine drum it'll be fine.

 

[John D v2.0]

Will this help. https://www.screwfix.com/p/floplast-washing-machine-trap-white-40mm/18640

spot on, although the floplast is a bit rubbish, i'd recommend a few more pounds for a better one:
https://www.screwfix.com/p/mcalpine-standpipe-appliance-trap-white-40mm/94360