There are several ways to use one jacket with steam and cooling water to heat and cool a tank. Condense the steam in the jacket to heat and run cooling water in the jacket to cool is one. This way is rough on the equipment and it is less common today than it was 40 years ago, but I'll say it's not uncommon. One version of a "tempered water jacket" circulates water through the jacket and a "steam heater" and a "cooling water cooler". If heat is needed the steam heater is on, and if cooling is needed the cooler is on. Today, this way is more common than the first way mentioned.
Good luck,
Latexman