[Richard L]

If the yellow led comes on whilst spraying (or not spray), it will be a failsafe activation. Nothing to do with the tank level sensor.

"B" led only comes on after the system is triggered. It will turn off if the flow goes outside the flow window. You can "assume all is well" when the "B" led is lit through out the spraying period.

If you see 7-8 bar at the gauge, it will trigger the failslafe because it has exceeded the upper limit of the flow window. (WL). Another reason for the excessive indication on the gauge is probably due to part of the hose is empty between the valve and jet.

During the first 1/10th second or so seconds of spray, air inside the hose will be displaced by the water until the water reaches the jet. Once this is purging sequence is completed, the gauge reading will be lower (5-6 bars instead of 7-8 bars).

You can avoid the over-shoot of WH (upper limit) and avoid triggering the failsafe (yellow led) by the one of following action:

1. Increase the failsafe delay on the controller (clockwise)
2. Shorten the hose length between the FAV and jet
3. Create a downward hose loop between the FAV and jst so that gravity will help keeping the water inside the hose.