spyderman4g63

I replaced the venturi valve with a straight piece of hose. I tested the thermistors that were in the hot tub and the ones from my old heater. One of them was out of range by 200-400 Ohms. I suspected that one of the new thermistors was bad. I put the thermistors from the old heater in and everything is working now. Thanks so much for the help!

I've taken the filters out long enough for the problem to occur again. I do have hard well water. I have a breaker for the heater and one for the rest of the spa. I left the heater turned off and turned the spa turned on. It still goes in to the mode with the flashing red light after a while. That makes me think it's not the heater actually overheating. I can check the ozone valve. I don't actually have the ozone generator hooked up (it went bad). There is just a check valve that draws in air. edit: Is there a way for me to test the high thermistor?

I have a 98 Hotsprings Sovereign model. It just started shutting down with a red blinking power light. From what I've read that indicates the heater shutdown as a protection. In the past year I replaced the circulation pump, heater, and thermistors. It ran fine for the past ~6 months. Now I'm getting the blinking red light. If I reset the breaker it takes a good 20 minutes before the light starts blinking and the spa shuts down. I put in a service call to a local company but I'm not confident in their abilities either. They suggested "trying" to replace the heater relay. I would think if the relay was bad the heater wouldn't kick on at all. I have tested the input and output voltage in the past and never noticed any issue with those relays. Their next suggestion was trying to replace the entire IQ board. He did note that he expected more bubbles to be coming out of the heater. That makes me think something is wrong with my new circ pump or some type of blockage. Filters are new. I've already put about $800 into this spa that I bought for $500. I don't really want to put another $800 just to have the spa guy swap parts and hope for the best. Any ideas on what I could test?