looks like you have a fan coil that is cooled with chilled water. you must be in a highrise or loft downtown. The rust on top of the water heater is mostlikely from the evaporator main drain line getting stopped up at one time and water overflowing and falling on the top of the water heater. the copper to steal connections look sound so you should most likely be fine. elwctric water heaters last a long time and our fairly inexpensive to replace.
@SwaggyG:
Thank you! 😀 4951