megaflo thermostat settings

can't find a simple guide for the thermostat settings

1= ?'c
5= ?'c

water is set at 5 out of 6 I think now and very hot. Might drop it a touch but also don't want the water too cool so that when using shower it takes more hot and so drains' tank too quick.

does such a guide exist?

I have the hatrae sadia cl210 model

 

gone from about 3.5 to 4.5 and its a big difference, still intrigued if there is a real temperature assigned to each number though