Catalina Spa intermittent heating.

[austinlegro]

Hi, hope the hive mind can help.
I have two heater issues that may be related.
Catalina Spa, Balboa CAT105 control unit.

First problem has only ever happened once.
Heater stayed on despite no pump operating and no heater light illuminated.
Water boiled in heater tube making popping noises had to turn on pump to calm things down but water continued to heat above set temperature.
Shut down tub, reset and normality was restored.

My limited knowledge makes me think that a relay was stuck shut despite no input from the flow sensor, thermostat or pump?

The second issue is ongoing and is the opposite of the first.
When the tub is turned on the heater brings the water up to the desired temperature and stops heating.
When the temperature drops and the heater cuts back in the heater light comes on but the heater doesn't.
If I kill the power to the tub and reset it it will usually come back on and heat normally, but sometimes it won't.
Very occasionally lowering the set temperature (to cancel the heater demand) and raising it again (to induce the demand) will trigger the heater to start.
No error code, clean filters and topside display of temp and heater status all normal.

Basically, the heater tube seems to be doing its own thing despite the control panel saying otherwise.

Again, my limited knowledge makes me think a relay is not closing that should.

Is there a dodgy relay that could produce both of these issues?

thanks

 

 

[CanadianSpaTech]

Sounds like a relay issue but can't be 100% from here. Post photos of the circuit board and the schematic on the inside cover so we can see what you have.

[austinlegro]

As requested.

Thanks.

[CanadianSpaTech]

Might just be a shadow but looking at the photo the K4 hi limit relay top right might be damaged. Can see black on the fuse beside it. Remove the board and look on the back for darkened or burnt areas. Let us know results

[austinlegro]

Symptoms have changed following further investigation.
Sometimes, lowering the temperature setting thus cancelling the call for heat, and then raising it again will cause the heater to kick in.
Only way to check is to look at my energy meter and see how many kW we're drawing.