I'm thinking on using one of these to install a washing machine and a condenser tumble dryer to the sink's drain pipe of my utility room. double drain

Why is one inlet pointing upwards and the other one downwards? do I need to have any special consideration for the height of the appliances, etc?

I know that a washing machine should be plumbed between 60 and 100 cm for example. I'm trying to avoid the water from one appliance or the sink ending in the other.

  • 2
    Both devices probably require air gaps or standpipes (with dedicated traps), so this probably won't be legal. The inlets can be swiveled, so that's just for example.
    – isherwood
    Feb 17, 2020 at 20:42

1 Answer 1


As indicated by isherwood your air gaps are mandatory. This is to prevent return of waste water into the appliance. In your setup you have an air gap but only one and also only one trap. It is better to construct separate air gaps and traps for each unit and combine both after the traps into the sink.

Construction can be straight forward: Take 2 traps and combine the outlets. Place some 10 to 12" pipe on top of the trap and put the appliance hose directly inside without a seal. The gap is then formed by means of the space between the hose and the pipe.

  • When you say I have an air gap, do you mean the one produced by the p-trap?
    – zom-pro
    Feb 17, 2020 at 22:49

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