No hot water pressure

Would the line connect in the back. If it does how do I even get at it there is no access from outside or under the sink

On the water heater where the hot water line hooks to the heater.

Where would the check valve be located . I don't see anything on the front of the heater ?

full-timer wrote:
Sounds like the check valve at the water heater is plugged up or broken.

He is correct! I recently had exactly the same issue. I replaced the plastic check valve with a brass check valve - problem solved!!!

Sounds like the check valve at the water heater is plugged up or broken.
X2

Water does come out of pressure relieve on the heater unit. When I open it

Sounds like the check valve at the water heater is plugged up or broken.

Bypass connects cold inlet (bottom valve/lie) with the hot outlet (top valve/line) that is why you can get cold water flow thru hot water side.

Normally with a 3 valve system on water heater no check valves are used.....normally.

Cold inlet allows water into WH Tank......valve should be OPEN
Hot outlet allows water from WH Tank......valve should be OPEN
Bypass...should be closed (Open when bypassing WH Tank. Close cold/hot valves)

Something is plugged up.
Most likely the hot water outlet/valve

Could be cold inlet....easy to check by opening the Pressure Relief Valve on WH Tank (CAUTION..Water could be very hot and will splash)

If you have water in the tank (flows out PRV) then you will need to disconnect hot water line at water heater and check for plugged nipple or if hot outlet valve is not opening. (Turn off water supply and have a bucket/towels ready)

Sacrificial zinc broke up and is plugging the line?