I bought this set for my Miele dryer, to avoid having to constantly drain condensate. The installation is self-explanatory. Along the groove cut the drain tube and install the hose end with the smaller diameter. The check valve with an arrow shows the flow direction of the water, it is mounted at the other tube end having the larger diameter. Install hose of the dryer even on non-return valve - ready. That the drain tube is smooth without grooves, I see no problem. The outflowing water is not under pressure and the hose clamp holds very well. I have blown into the tube - not even air leaves the valve against the direction of the arrow through. Reviews the report on water in the dryer, in my opinion, may be the cause have only incorrect installation. I highly recommend this part fully. Incidentally, the same type as original for my dryer will cost almost four times !!!
