So, I was going to relax in my spa the other day when I saw it would trip over and flash “SF” on the control panel. Here is what I did to fix it.
SF stands for safety Suction Failure. It comes up when your hot tub doesn’t suck. Typically when something doesn’t suck, it’s a good thing. But here – it’s a problem! Water can’t be sucked into the water pump, typically due to blockages. Obvious visual checks showed no blockages on any inlets. Hmm.
Before the next step – TURN OFF THE HOT TUB CIRCUIT BREAKER. Don’t die because your hot tub doesn’t suck. THAT would suck.
Next, I opened the side panel and disconnected the safety suction from the controller motherboard. It’s the black/red wire with the brown header I’m holding below.
There is (supposedly) another check on the heater so this is redundant and it was for a quick test anyway. Turning the circuit breaker back on and turning the hot tub jets to full, nothing tripped this time. Awesome! So definitely the safety suction unit/sensor.
The safety suction unit has a grey wire coming out and going to the control unit. It also has a blue rubber cover.
If you gently pry the blue rubber cover off, you can detach the two wires and unscrew the entire safety suction unit – which stick 90 degrees off the inlet pipe. Note that if you do unscrew it fully you’ll have a little fountain at that point and it will eventually drain your hot tub. It’s quite low pressure, so you can just screw back your new (or old) safety suction sensor without necessarily draining the entire hot tub.
In my case, I put the old non working unit back but disconnected it from the main board. I’ve ordered a new part online (Amazon). As you can see, I needed part # VM12540E-250WI
I’ll update this post when I have the replacement part and have installed it next week.
UPDATE: I got the replacement part and installed it. All good.