Your working water temperature will vary from day to day, according to the ambiant temperature.
Also there is no base settings for running the heaters as everyones set up will be different, flow rates types of hoses ( thermobore etc )
I find the best way of judging the daily water temperature is to just put your hand in front of the brush and judge how warm the water is.
If its a cold morning like today, just have it luke warm, you may be able to increase slightly during the day
Hope this helps