As stated: Add the water to the tempering tank at slightly below your desired temperature, and allow the heater to bring the temperature up to the set point. Allow the chemicals and wash water to equilibrate to the temperature. If the tendency is for the temperature to rise to levels that worry you as processing proceeds, then simply add small amounts of chilled water to guide the tempering bath temperature down a bit as processing proceeds. Most black and white work is quite tolerant of a few tenths of a degree one way or the other. The hose attached to the solenoid will bring cold tap water in to bring the temperature down. However, during the summer many of us have tap water that is too warm, and using a chiller is much too costly. The low tech addition of chilled water as needed works well. Don't forget that once developing is over, the other steps are less temperature dependent. Indeed, if the temperature is about 2-3 degrees F ( or even a bit more ) one way or the other it is likely that the fixer and washing water will be absolutely fine.
Let us know how you do.
Ed
