Mostly, is my circulation pump flowing in the right direction? Our previous tub didn't have a separate pump, just the big one.
The current tub is a Leisure Bay with balboa controls (I believe). I picked it up to replace our previous one (Gerico) that more or less fell apart. The main pump motor looked as if it had been on the Titanic. The circulation pump worked, but leaked like a sieve. I installed the motor/pump assembly from the old tub and put in a new circulation pump. It heats up normally, but after being used it shows "Oh" on the display & shuts down. Tonight I noticed there is a jet near the bottom that when the main pump is running, returns water to the soaking area. When the main pump is off, the circulation pump is drawing water IN through this orifice. As I'm sitting here typing, I'm thinking that when the bathers get out & turn off the main pump, the heater comes back on (wired for 110- heater cuts off when main motor runs). However, if it's running backward, the water isn't flowing properly and a thermostat is shutting it down, sensing water that's hot where it's not supposed to be that warm. *light bulb moment* this would also explain why I've had trouble with the pressure switch! If it is supposed to be on the pressure side, but it's on the suction side, that would explain it! EUREKA! Problem solved, unless you see a flaw in my logic.
I think I've got it now, but if anyone has anything to add/subtract or advise please do!