GeoffTK

Yes!! To close the loop on this, I just had to make some minor adjustments to the pressure switch. The "pressure regulator" (not sure what the name of the part on the switch is actually called) needed to be loosened (left turns) a few times around. And then, bingo, the heater was able to turn on.http://www.hottubworks.com/blog/hot-tub-pressure-switch-adjustments/This helped lead me in the correct direction

Hey all, I just fired up an old Cal Spa from 2001 (model 2100 series). The pressure switch was at the connections, so I replaced that. When I turn the jets on their highest setting, the heat light comes on, but if the jets are off, or on any other setting, the heat light stays off. What might be causing this? Thanks