I needed a hot air rework station. One without the fan built into the hand piece, nor one that was a soldering iron / hot air combo.
There are some units with a floating ball air flow indicator that some have said wasn't of much use.
I settled on the Yihua 8508D and discovered that Sparkfun was selling a similar unit, so this cheaper unit seemed a good choice.
It arrived well packaged, the box wrapped in Yihua packing tape as though it had just left the factory. I plugged it in and .... nothing.
Internally the blue leaded connector had worked loose. It and the connector beside it had not received the red gunk treatment and
there was barely enough grip to keep it secured once reattached.
On my unit the hot air gun was poorly earthed by a few strands of copper on the front solder lug.
The solder lugs reuse the bolts for the rubber feet and there is no shake proof washers.
Paint is well applied to the steel chassis but unfortunately insulates the front panel from earth.
Calibration is simply setting the desired display temperature then tweaking the uppermost pot until the air temperature matches.
The bottom pot sets the absolute minimum airflow when its dial has been set to one.
Its smells something awful, and I'd advise trying to burn the fumes off outdoors.
The pump is well made though in places the silicon tubing it too short and kinks into the airflow.
The temp display always shows 100 when fully adjusted CCW and 450 when fully CW. But when the heater pot is a just inside of that
travel range only then is the true hot air gun temperature shown.
The accuracy is terrible and I simply note the settings and record the air temp with an external thermocouple.
In short it's very effectively for SMD removal and repair.