I searched through the 'electric heater problems' posts but I couldn't find anything describing the problem I have here. Please redirect me if it's there and I missed it.

I went away for a few days and while I was gone, my hot tub was used and the top was not locked down. A pretty big storm came through and lifted the top open and almost half the water was gone by the time I got back and the temp of the water was down to 76 degrees. I have a Dynasty Spas Excalibur series tub. Ave daily temp was mid-70's and mid-50's at night so no freezing problems.

I refilled the tub but now it won't heat properly. If I manually turn on the pumps (there are 3) then it will heat during that time (about a degree or so during the 20mins that they stay on). If I leave it alone, it won't heat even though the circulator jet runs with normal flow.

I checked the cutoff switch to the heater. If I leave it circulating with the pumps turned off, it kicks an error if I unplug the switch and kicks off the error (blinking dots like a power outage) when I plug it back in.

So, to put it simply (and add a little bit for clarification):
- It heats up when I turn on the pumps but only while they're running
- It has lots of circulator flow when the pumps are off so it's not clogged up
- The heater does not kick on (measured at the heater 240V posts) unless the pumps are on
- All the fuses are good

Anybody have any idea what could be going on or know where I might at least find a logic diagram to the system?