My brother has a little(5 gallon or so)RV water heater under his sink in his shop for hand washing. You could just run cold water only over to the sink.

He said it didn't cost much, and I'm pretty sure it just plugs into a 110 socket.

Would the winery sanitation setup lend itself to a booster heater? 

Our water heater in the milkhouse had to have a different thermostat installed to make 180 degree water.

Mixing valves are available to temper the water for hand washing if that's the way you wanted to go.