There's a bloke on here reckons he cleans vents with the water on full flow and somehow, magically, the water doesn't get inside the vent. I can't remember who it is, but when asked if he could put up a video of the technique we never got one.
Its not me who made the claim bud but i 'usually' clean top frame, around the vent.
I can't remember the last time i got water through a trickle vent.
Certainly not on a regular uPVC stormproof casement.
I run the pump about half flow. If theres a crappy bit in the corner where I'm gonna be more than a few seconds ill disconnect or kink the hose to minimise flow.
Other than that, it's just crack on. I am quite quick (
) Maybe thats something to do with it?
Perhaps its something to do with the angle of the brush also?