Turned out today that the heater wasnt even on, I have a second one I'm going to use in the secondary, so used that as test in a jug of water, electrim heaters dont have any marks of temp on them, just a twistable adjuster, and the heater in the primary now, was so "un-tuned" it was way under temp and not doing anything.
I found that as I looked at the top of the heater, as per instructions and taking the cord exit as 12 oclock, the cable comes out horizontally as you look at it, I twisted the pointer to just level with the right hand side of the cable, and it heated my jug water to just over 20.3 or so then cut off, then started at about 19.6 or so again to heat, good enough
I pulled the one out of the fermenter carefully, wiped the crud off the top, and re-adjusted this one to the same as the jugs one, spot on.
A little annoyance though, I have the opaque look fermenters with the twin handles and the screw cap, and when you place the heater in correctly, obviously you cant see the light on it, shame the homebrew market cant design an in line light that could trip with power surges (on and off), like on the heater itself, great for a clear fishtank, not much cop to us though
Also, today, the smell of the released co2 from the bubbler is starting to resemble beer now, and not so malty like the start, so i'm happy that its all going to plan so far.
Thanks for reading, happy brewing, lee