I'm working on restoring a 81 Excella Motorhome
Best guess I have heard from an old timer at the Central Trailer Supply in Albuquerque (highly recommended btw) is an on demand water heater?
I'm hoping it is a fancy drink mixer to go with the blender
pic 1 is 5 buttons next to sink
pic 2 is wires running to a box under sink, with 10 tubes running from the top (connection to 110v power not pictured)
pic 3 is close up of connection
pic 4 is the faucet where 5 of the tubes go, the other 5 are not connected to anything (maybe water at one point?)