Shane -
Absolutely you can run both at the same time! The manual plainly states that doing so is a good idea, increasing the recovery rate.
Yes, when I made the comment about not being able to use both at the same time, it was when my new TM was brand new to me. It was based on that misleading control panel. I should go back, find that comment, and change it. I asked the factory why they had set it up that way (one or the other, but not both), and the answer was basically "Huh?" Since then, I sent them a picture of my suggested panel, and they told me they aren't using that panel at all any more, and had changed back to the Suburban OEM control panel. Bottom line, I think there is a surprising mix of panels out there.
BaconLover -
The Suburban water heater comes from Suburban with a built-in rocker switch that controls power to the electric element. Take a look at the blue arrow in this picture -
https://www.trailmanorowners.com/for...&pictureid=447
This switch is accessible only from outside the TM, which is a bit unhandy, and I don't think many folks liked it. The factory pays attention to these things, which pleases me. They decided to experiment, removing that switch from the water heater and relocating it inside, on the control panel. It's an idea I like, and I'm pleased that they were willing to try it out. But in my opinion, and mine only, they fumbled the control panel layout, then reached the wrong conclusion about its utility, and returned the switch to the original location. My preference would have been for them to leave the original switch in the original location, add an inside switch in series with it. Over the years, many of our members have done exactly that, and have reported that they like the result. If the factory then corrected the labels on the control panel, it would be a nice assembly.
Scott at Custom RV was exactly right about your control panel. One switch controls the electric side only, and the other controls the gas side only (which is why the word "ELECTRIC" was blacked out). Take another look at my post #17 above. Your description matches my first pic. You need a plate like the second pic.
So anyway, my guess is that the confusion you are seeing is because you are seeing a mixed bag of instructions for the old setup and the new setup.
Bill