Hi .what jet size do you prefer ?at the moment i use 2 mm and just purchased 1.4 mm from gardiners. Sometimes i like the 2mm for the old wooden frames where you can't really insist on the frames and there isn't to much splash from the jets. But sometimes i prefer the 1.4 mm(i previously used 1mm jets) especially for upvc windows as i use less water and seem to work faster too.
I think I'll add both sizes to the brushed as there are 4 holes and swap as i need them but can be a little complicated and would be time consuming .
We used to use 3mm jets in the early days before controllers were available. I couldn't work fast enough to save water with a Shurflo pump working at full speed.
I still have an old Vikan brush with 3mm jets I used to use on a couple of blocks of flats/apartments. Using a controller the water flow just trickled out of the jets where the jet would be stronger using 2mm jets. This is only to be expected as the 3mm jets are twice the size of the 2mm ones.
Son tried the 1.4mm jets as he felt they would save water as he prefers to use a backpack. He used those for a long time but when I changed the brush head with 2mm jets fitted he never complained.
I prefer 2mm pencil jets every time.