Heater too hot - Artesian Spas

[hande]

Hope someone can help with this. I have tried most of the troubleshooting answers I could find.
2014-2015 Artesian Spas Captiva, 5.5kw heater, 3 pumps plus circulation, Balboa MBP20VLV
Spa will heat up to the set point and sometimes it will exceed the set point. Heater too hot error shows up Then it goes into safe/economy mode. Water will cool down but heater will not come back on until I activate the buttons then it will work fine until it repeats. (Only has exceeded tub temp of 107 once in last 2 weeks other time error shows up at set temp or just over (panel temp readout verified with independent floating thermometer that polls every 10 minutes.)
replaced both temp sensors.
Have ran it without filters.
Heater has 240 volts. drawing about 22.5 amps when on.
Has a circulation pump to the water fall which has full width of water coming out of it. (water fall is usually 2 degrees higher than current tub temp with heater on)
Heating on display will go off then power to element also goes off.
Checked circulation pump body for high temp over period of 12 hours and it was around 110-120 degrees so not overheating and shutting down.
Today triggered control panel at 8 am at 91 degrees. rose to 99 in 1.5 hours so circulation is there but rise seems fast.
Pulled the circuit board today , no scorches, all relays click on and off. zero resistance when closed, back to resistance when open.

Not sure what else to check.
Thanks for any help.

 

[Newdude]

*bump*

Hang tight for @RDspaguy

 

[jimbethesda]

What is your set point when this happens?

 

[hande]

Set point has been anywhere from 99 - 101. Doesn't seem to make a difference

 

[RDspaguy]

Post pics of equipment area, circuit board, and wiring diagram.
Typically a spa gradually heating beyond setpoint is a hot pump or long filter cycles, while rapidly heating beyond setpoint is a stuck heater relay.

Checked circulation pump body for high temp over period of 12 hours and it was around 110-120 degrees so not overheating and shutting down.

While not hot enough to trip the thermal cutout, it is definitely hot enough to overheat a hot tub running 24/7.
Remove front panel and run it. If it stops overheating improve venting or replace circ pump.

 

[hande]

Thanks for advice. Was going to try that but when i powered it back up it seemed like the circ pump was shaking and thumping like it could not start or was binding. Then I heard the boiling of the water at heater and control panel wouldn't bypass priming mode so I shut it down. Turned circ pump by hand at back end and no binding but found small leak at wet end. Went ahead and ordered a new one, since its over 8 years old, will eliminate it as overheating potential cause and fix leak. Will update with pics and update info after install, hopefully arrives fri. Any thoughts on control panel locking me out.

 

[RDspaguy]

You ran the heater with no pump causing a boil-out which tripped every safety feature it has. It can damage the heater and sensors on most control systems, as well as pressure/flow switch and board on others. Lock-out until power reset is typical usually with an error displayed (oh, hh, hot, etc).
Post pics so I can see what you've got.