In my experience, the temperature in my darkroom is rarely much above 20C, Even when the outside temperature is over 30, inside it is somewhat cooler. The issue is that when the tap water is warmer than 20C, the unit can't cool it down, and in that case, just putting a 1L bottle of ice in the tempering bath quickly brings the temperature down to 20, and the thermostat and heater then hold it at 20. Unless I have a huge quantity of film to develop, the 1L of ice keeps me at temp for plenty of time to get several batches of film developed.
Originally Posted by Matthew Cherry
So for me - it really isn't an issue. Perhaps if I lived in a warmer climate it would be more of an issue.