Dear Rabbi, Is it permissable to wash ones face in hot water on yom tov?

Shalom, Thank you for your question. It is permitted to wash one's hands and face with hot water on Yom Tov. In fact, one is allowed to even heat water up for this purpose – of course being careful to make sure that the laws of using a fire or electricity are well guarded. Most hot water systems are permitted on Yom Tov, and may be used to wash your hands and face. (There are some hot water systems that are forbidden to use on Yom Tov, such as a tankless water heater with electronic ignition, but standard hot water systems are permitted). Blessings.