Hi Jerseygsp,
Welcome to the Heartland Owners Forum and to the family. We have a great bunch of folks here with lots of information and all willing to share their knowledge when needed.
The unit may have been built in 2009, but is a model year 2010. If the registration says 2010,, that is what it is considered.
Most likely the water heater will work on 120v, but you need to make sure it is full of water before turning on the switch. If the switch on the bathroom wall is like a normal wall switch but has red handle it most likely turns on the water heater. Again make sure you run water through the heater and then turn on the switch, if you get no hot water after a few minutes, the element may be burned out.
Be sure and check out our
Heartland Owners Club. Join us at a rally when you can and meet lots of the great folks here and make friends for a lifetime.
Enjoy the forum and your new to you unit.
Jim M