Air probes generally need a bit of damping to slow their response to draughts and sunlight and such. Putting it in a wall housing should suffice, but there are other tricks used like sticking the probe into a hole in a pingpong ball...
you might need to go into the settings to see what the HW hysteresis is- what the cut-in *and* cut-out temperatures are. also does the tank have one immersion, or two?
first thing to do is to comfirm which Band you local celltower is on- your phone's diagnostics might show this, or download an app like Networ Cell Info or the like.
Yep, on our Cool Energy unit the main pump is under PWM control based on in-out Delta as far as I can see. Min, max, and startup speed are all configurable though.
I hate to say it but... there's a global pandemic thingy. Administrative and physical processes have ground to a halt in all sorts of ways- a friend's 12yo daughter recently waited five months for an Urgent cancer investigation. It's a grand excuse this COVID but even when it's not an excuse it slows things down to walk-ing-in-custard speed.
If actual rules are being broken then sock it to them with the full force of legality or enforcement. Else (sorry) you're gona have to "suck it up @ToughButterCup" just like the rest of us?
we had an "industrial" segment in my Industrial Physics and Microcomputing course at Napier. One day a week at the Jewel& Esk vocational college. I've a tap wrench, a toolbox, and some random PCBs to show for it...