Spa Heating me too!

[SandraMarie]

Pool was drained, everything off for a month. The spa heater sounds off, the return pipe is hot to the touch, said only getting barely warm return water. The expanded pipe has visually looked that way for years, my huge concern is that a valve is set wrong.
Can anyone take a gander at the set up and clue me in on any drastic error, please? I'm afraid the heater might blow up!

 

[DrewLG]

That automated valve after the heater -- the one with the box on it that says "CVA-24" -- seems to be blocking the flow from the heater to the returns.

A photo of the valves taken from the other side -- standing between the heater and the valves -- would be very helpful to confirm my impression that the flow is blocked.

Do not run your pump with the flow blocked; it will overheat and may be permanently damaged.