Does natural convection "instant" hot water ever work?

[Robert Gift]

For us, warm water would be nicenough.
2-story house, built 2000. 50-gallon water heater in the basement. Copper plumbing.
A return Pex line from the 2nd floor main bathroom coud be connected to the water heater tank bottom outlet.
But would a one-wayalve impede the return water enough to prevent natural convective circulation?

Clarification: Swing gate oneway valve.
Position it at a slight angle so the flapper would remain a litttle open to allow theavier cooler water to return.
When a faucet it opened, the reverse water flow would push the flapper shut. Or would that cause an oscillation?

Thank you.

 

[LLigetfa]

But would a one-wayalve impede the return water enough to prevent natural convective circulation?

A swing gate check valve would be required. A spring loaded would most likely not open.

Instant hot generally refers to a boiling water dispenser.

 

[Sponsor]

 

[Fitter30]

Swing check at heater. Last 15' of return line uninsulated. The supply and return should be insulated. Two stories work the best.