Hot water not working in Casita 2007

[sinogbus]

Hi, just bought a used trailer so I'm working through the problems...

I can light the gas burner, it does burn pretty strongly for like 10 mins, then reduces down to pilot. When I turn on the hot water faucet, after some sputtering, I get 5-10 secs of hot water, then it goes back to cold water temperature.

There is good amount of hot water coming out of the relief valve.
The bypass valve is pointing downward (per photo).
I've changed the anode rod, and cleaned out the inside with a sprayer.

I read that there is a check valve on the hot water outlet, but I'm not sure if that's the problem.

Thanks in advance for any help!

[Raspy]

In your picture, there is clearly a check valve on the cold intake bottom fitting. See the brass fitting below the three way valve? No need to read about it, there it is. And since the three way valve is installed with hand nuts, just take it out, look into the end and make sure which way the handle must be set to allow water to flow toward the tank, and make sure it is clear. I see what appears to be teflon on the check valve threads. And that appears to be a swing check. Is it possible that valve was recently removed and installed backwards? If you unscrew the PEX fitting from the check valve, you should be able to push a pencil through the check valve and open the gate, unless it is stuck or backwards. It looks like there might be a spring check on the hot side. Unlikely it is stuck, but with the faucet open, you could tap on it to make sure it is not stuck.

[Casita Greg]

My two cents worth says that your hot water heater OUT water line check valve in the back of your WH is crudded up, and needs a few good whacks with a small hammer or the side of a crescent wrench to bust loose the caked on mineral deposits that aren't allowing them to open. Those check valves do crud up from time to time, and to get it unstuck, generally, (while the water system is pressurized,) a few good solid whacks on them will free them up. Don't be bashful about smacking them. Yeah, not hard enough to bust them off, but don't just give them a few "love taps." Hit them like your mad at them! It'll probably knock the crud off the check valve seat and get it working again.

[sinogbus]

Figured this out - so the bypass valve was installed incorrectly! The switch, needs to face in (towards the water tank), not out as in the photo. This valve (when in downwards position) is direction dependent and needs to be installed with the switch facing inwards. Thanks for the help all!