No clicking sound

You have red wires connected to bottom of gas control valve?
Is this a power vent model?
What model, what brand water heater?
Is new thermocouple is finger-tight plus 1/4 turn and not shorted against gas control valve?
http://waterheatertimer.org/How-to-test-water-heater-thermocouple.html

Copy following link for safety magnet:
Magnet will click closed when pilot is turned off. Put butane lighter on end of thermocouple and listen for clicking sound.
http://waterheatertimer.org/pdf/Safety-magnet-Gas-control-valve.pdf

Copy following link for troubleshoot by type of gas control valve:
http://waterheatertimer.org/How-to-troubleshoot-gas-water-heater.html#intellivent

Bad gas control valve:
Low gas pressure, air in gas line, inadequate air supply, clean the air intake, tripped FVIR system, etc.

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

http://waterheatertimer.org/Troubleshoot-Bosch-Tankless-water-heater.html#flow
1) Tankless require minimum flow rate before burner will activate.
2) Sounds like the water pressure drops quickly when faucet turns on. This implies combination of problems including sediment build up inside lines, crossover at single-handled faucet, or sediment filter clogged or water softener clogged.
3) Low flow faucets can reduce needed flow rate.
4) Other problems can contribute: sensor failure, loose wires, PC board failure, high temperature setting, cold incoming water temperature during winter months.

sediment build up is usually causes thumping and noises from tank. it needs flushed out. models, where the heat source is beneath the tank. The burner heats the water under the sediment, leading to a build of steam. The steam finally escapes as bubbles, which can cause the sounds.

have a good day !

the unit should still be under warranty sounds like a sticking solenoid problem

http://waterheatertimer.org/How-to-troubleshoot-electric-problems-with-water-heater.html

You have a 240V electric water heater because you have an upper and lower element

The upper thermostat works in the manner you have discovered.
In residential electric water heaters, the upper element is ON or the lower element is ON, or both elements are OFF.
This is called non-simultaneous operation.
Non-simultaneous operation means the elements are never turned ON at the same time.

Because water heater thermostats only turn off one leg of the 240V circuit, the upper and lower elements will always have power on the two screws, but not across the two screws.
This power is 120V and the circuit is not complete so the element will not heat.
So if you test any element, it will always show at least 120V
Only when the thermostat clicks ON is the 240V circuit completed, and the element turns ON.

Identify the problem:
1) The shortage of hot water is caused by a bad upper or lower thermostat or a bad lower element.
We know the upper element is working because you have some hot water. If the upper element was burned out, you would have no hot water because the upper thermostat would never click over and send power to lower part of water heater.

2) It sounds like your upper thermostat is clicking on and off, so I would test the lower element.
http://waterheatertimer.org/How-to-test-water-heater-element.html
http://waterheatertimer.org/Do-it-yourself-water-heater-timer.html

Add a comment if you need more information, and I will help.
The do-it-yourself link above will give you full electrical how-to for self-fixing electric water heaters.

the clicking could be from thermal expansion or the thermostat turning off or on. Be sure it's a clicking sound and not a sizzling noise. Sizzling noises are caused by loose wires or burning contacts, this is dangerous.

The hot side (top line) should have a check valve between tank and water line. I'd replace it. Be sure you install new one the right way. Stem, spring etc should be facing in tank.

Remove power, disconnect remote terminal. Restore power, open a hot water valve and see if you get any hot water.

HTH,
Mike

there is also a reset switch on the unit,its comparable to a G.F.C.I, check this too