GraemeSpa

The original post has the control board pictures. One thing I've never tried is unplugging the sensor and leaving it unplugged to see if the heater comes on or not, I've always just quickly unplugged, let the pump start then plug back in and the heater then goes on. Thanks

I was under the impression that the board won't tell the pump and heater to turn on unless it has an "open signal" from the flow sensor. So by unplugging it, that changes the signal to open as it thinks the flow sensor is closed. The flow switch manufacturer, Harwil, told me to bend the metal "away" from the upright so it didn't read any false closed signal. I will try the opposite and bend near straight, I've made sure it's clear and clean, I've tried tweaking the angle a few times by a few degrees and nothing. Thanks

Thanks, here you go, FYI I never see a flashing FL code, once unplugged it then shows the temp (usually around mid 90s as it's been off all night) and it kicks in the pump and heater. Then I just plug the sensor back in. Appreciate the help.

So I have a beachcomber 578 spa, it was working fine since we bought this house about 6 months ago. Then we got an FL code so I cleaned out the filter, checked for air pockets etc but ended up buying a new flow switch and then it worked again for about 6 weeks, I then bought a new flow switch as I thought the first one was faulty. The new switch did indeed work and the spa was all good for about another 2 months. Now I'm getting the same FL code once it reaches temp, circulation pump will shut off and it sits till temp drops below setting and then the FL code hits the panel. Now when I unplug the flow sensor it fires up immediately and the I plug it in, that allows me to use the tub intermittently. I tested the flow for ohms and it's behaving normally, but the board seems to be getting a closed signal from the flow sensor when its open, hence the solid FL? Any thoughts? I should mention I did have the pump rebuilt professionally too.