What you may want to make sure of is that you have the line open from hot water into the lines in your unit. My red light stays on all the time, as I believe it should, telling me it's on. But, I forgot to open the line to the whole unit and after my first cold shower learned quickly what the setting should be. They told me all the angle cocks should face in the same direction, on the water lines that is. Hope this helps some.
Jim & Linda Tator
2013 Crusier CF34SS
Ford F250 PSD 7.3L Bully Dog
154 nights in 2013 - 4,370 miles