Jody,

The webasto is a diesel fired burner which heats your water, and provides for heating as well.

As a difference to the cruise airs, which might also provide heat, the webasto system can work on 12V, while the cruise airs require that you either be plugged into shore power, or running the generator.

The webasto's generally work very well, and are easy to repair/maintain. There are several threads here in the forum regarding various repairs.

I don't believe cruise air heat functions below about 40 degrees F. IN that case only your webasto is going to keep you warm.

Ray