No hot water pressure. Atwood.

Did your old WH do the same thing ? What does that tell yya ?

Open the pressure (pop off) valve when the water is NOT heated and see how it flows out of that valve. If you have the same problem, then your input to the water heater is screwed up. IF water flows out of the Pop Off valve good then your upper exit fitting has a problem. Doug

Here is a typical water flow chart for typical trailer...



Also on my hot heater I am using the three valve bypass line for winterizing. Perhaps you dont have the valves turned all the way for the proper positions. Make sure the valves are fully positioned in the NORMAL mode.



Just a couple of my thoughts
Roy Ken

As mentioned by wrvond, this is a classic symptom of an obstruction. The longer the surge before slowing, the further upstream the obstruction. Because it surges for only a second, We can safely assume the obstruction is downstream of the WH and not on its inlet side. Maybe you can disconnect an upstream fitting and blow compressed air back through it from the faucet? Also check to see if all the faucets in the RV react the same way. We're assuming the cold is fine?

The check valve screws into the top outlet on the water tank.

I replaced the entire tank. Didn't realize there is a check valve in the line. I thought it was more of an air lock in the line because sometimes it sputters. No kinks or pinches in the line, and was very careful with the teflon tape. So there's nothing clogged up in there.

Hot water outlet.........check valve failing......did you replace or use old one?

Sounds like you have a kink or pinch in the line. When the water is off, it allows pressure to build up, but when you open the faucet, the water runs out faster than it can get by the restriction.
Go back and inspect your water lines, and ensure you didn't clog any fittings up with improperly wrapped anti-seize tape.