It take time for your hot water to rise to the top of the hot water tank. You need to give it 30 minutes. Did you?
Also, your WH will shut off the gas if there is not thermal transfer. I.e., without water in the tank, the tank will heat up fast and the thermostat will open, shutting off the gas.
Does your sink have 1 handle or a separate hot and cold?
What is your water heater type? We have different coaches, but your water heater is like mine I'm pretty sure.
Did you open your purge valve to let some water escape from the top? This will let you confirm you have hot water in the tank. If you have hot water in the tank and you are not getting any hot water out the sinks, with one handle faucets, what is happening is your cold water is back flowing through the hot water side.
Answer: Those stupid, stupid check valves are stuck closed, and this is blocking the flow of hot water out of the tank! Also the stuck valve is the hard to reach one up top.
This happened to me on the road. And after 3 days of not being able to get any RV shop or Camping World to help a traveler, I decided to research it... and I saved $350 by doing the work myself... and in the end it only cost me $5.
Here's what you do:
* Pick up 2 water donuts at the closest RV store. Amazon sell them for, but for some reason they are expensive. I think I picked mine up for just a few bucks at Camping World and now I travel with 2 extras, just in case those white plastic Flair-it parts crack.
* Remove your 2 check valves protruding out the back of your HW tank. The top check valve is probably your problem valve, but it could also be the bottom check valve. ...Time to get rid of both I say!
Note: Chances are channel locks will NOT give the leverage you need to loosen these check valves, and you may not have enough room. So you need to get a 1-1/8" long wrench at HD or Lowes. And you should also get the 1-1/16" wrench too in case I got the size wrong, and which ever one you don't need you can return it later. TIP: Use a crescent wrench to confirm the wrench size.
* Drill out the guts of those check valves; and now you have a pipe nipple, because you can see straight though it.
* Use teflon tape and put the nipple back in the WH.
* Now replace the old rubber donut inside the plastic Flair-it fitting and tighten, but not too tight. You don't want to crack the plastic!!!
That's it. You will now have hot water again!
Job over... unless you want to do this as an upgrade:
The best place for a check valve is next to your bathroom sink. This is where the Hot Water line goes first... then it branches out to the shower and then to the kitchen faucet.
So if you can get to the hot water line before the hot water gets distributed, under your bath sink, you just add one 1/2" Sharkbite Check Valve to the hot water line-in. And now your how water will appear in the shower faster vs. the 5-7 seconds it took before. So this saves hot water on every shower you take.
Note: You don't need those check valves! They should never have installed them and they cause everyone lots of trouble. I took mine out 3 years ago and I am so glad I did! You will be too!