I've got a non-return valve I'd like to fit into my washer system as sometimes they take a few moments to squirt. I've moved my bottle into the rear storage bin on the drivers side and the pipe runs inside, across the sill up the inside of the bulkhead before going through and splitting to the jets.
Where should the valve go? At the bottom of the vertical section?
As close to the bottle as you can would make sense, that way less water drains back to the bottle and also requires less water to be pumped when in use to start getting the screen wet.
In theory it should make no differance as if its further away from the washer bottle it should still be air tight.Abit like if you suck on a straw then stick your tounge in the end if that makes sense.
Pete