Air locks are a relatively common problem in hot tubs, but they are simple to fix in most brands of hot tub. They occur when the water level drops too low or after a water change, and air gets trapped in the lines or equipment.
There are sensors in the hot tub that detect water flow or water line pressure to protect the hot tub heater from coming on when the water is not flowing past the heater element fast enough. When an air lock occurs, it is common for these sensors to detect low flow or low pressure, which results in the heater being disabled until the problem is fixed. It usually also triggers an error message on the topside control display, such as “FLO.”
This is normal and a useful safety feature. Do not disable this feature, fix the root of the problem instead. Watch this video to show you how:
So, if you’ve recently drained and refilled your spa and one of your pumps is not working, it’s most likely an air lock. And here’s a couple of steps we can do just to check and see if it is an air lock and fix it if it is. What you’re going to do is find out which pump it is that’s not running. So you’ve identified it’s this pump that is not moving the water. We’re going to check, take a look and see if a reset button has clicked out on it, and make sure that’s in, and make sure the shaft is in fact spinning.
So we confirmed the shaft is spinning. The reset button is in, so there has been no stall, overload on it. So we’re going to go and we’re going to take some simple household tools, a hammer and a screwdriver, and we want to loosen off the union to allow the air to escape that’s being in there. Because what it is the air lock is just staying and it’s circulating, but it’s not allowing any of the water to move. So what we would do is simply just back that off a bit, not too far, because you don’t want it to pop right off. You’re only going to do about like, say, one revolution. We will allow some water. So water’s going to come out, some air’s going to come out. And then that pump is going to surge and it will start running again.
It might take up to 3-4 minutes. Then once it’s running again, you will have more water, because it’s going to be able to pressure will be coming out. So, you will just snug that up again, not too tight. Just snug it up good to stop it from leaking, that’s it. And you’ve gotten rid of your air lock.