This is one of my most asked questions and I can see why looking at how small the power wires are on the unit.
If you follow the steps I laid out in the video you will have no problem wiring the unit and the controller.
You can get everything at the Home Depot or Lowes you can also get all the material at your local electrical supply house.
Just remember to unplug the unit before you wire any controller to the unit.
I hope you enjoy this video,
Mike

PLEASE USE A LICENSED PLUMBER TRAINED IN RINNAI'S LEVEL 3 TRAINING. FOLLOW ALL NATIONAL AND LOCAL PLUMBING AND GAS CODES AND TO FILE A PERMIT AND OBTAIN AN INSPECTION FROM YOU LOCAL BUILDING DEPARTMENT.