If water in an ammonia system gets into the compressor oil, it will cause a series of chemical reactions that create sludge.

The saturation temperature, or boiling point, of ammonia is the temperature at which ammonia molecules change freely from the liquid state to the vapor state. “Boiling” means that enough heat has been added to the ammonia molecules for them to break free from their liquid companions and join new friends in the vapor state.

Adding water to ammonia gives the ammonia molecules something extra to stick to and interferes with the liquid-to-vapor phase change. As a result, either higher temperatures or lower pressures -- both of which require more energy -- are required to achieve boiling.