Help! Hot Tub Air Lock! - Build a DIY Hot Tub

So you have emptied and cleaned your Hot Tub and patiently waited for it to fill up. You’ve scrubbed. You’ve cleaned. You’ve flushed solution after solution through the jets and now you can’t wait to get back into that tub.

Hold on! One of the pumps isn’t working. You can hear the motors running, but nothing is happening; nothing is coming out of the jets. Frustrating to say the least, but not the end of the world.

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It is possible that you have a large air pocket trapped inside the Hot Tub pump or plumbing lines; a problem most Hot Tub owners face at some point. Fortunately, in most cases this problem can be solved without the help of the professionals. But what does a Hot Tub air lock actually mean?

What is Hot Tub Air Lock?

A Hot Tub air lock is usually created when the Hot Tub is emptied, cleaned and then refilled. Air can enter the Hot Tub and be trapped inside the pump or the pipework if it is not forced out by the jets. When this happens, normal water flow is interrupted because trapped air blocks the path of the water. In most cases, you can hear the pump running but there is no water coming out of the jets.

If you have this problem with your Hot Tub, you should look to solve it immediately. Otherwise, the trapped air prevents the Hot Tub’s jets from working properly, which can lead to more serious problems that may eventually damage the Hot Tub. The pumps are not designed to be run without a load on them and this load is the water flow. If the water is not flowing through the pump there is a danger that the pump can overheat. Replacing pumps is not the cheapest so I’m sure we’d all like to avoid it if possible.

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How to Fix A Hot Tub Air Lock

‘Burp’ Your Hot Tub

Here are the steps to ‘burp’ your hot-tub.

Open all jets at once to try and let the trapped air out of the Tub. (Just opening them will not do it on its own so move to the next step)
Turn off the Hot Tub’s main control panel or circuit breaker. With no water flow, the heater is not going to run. What you want to try and avoid is if there is a less than normal water flow is the heater switching on. You will begin to damage the heater if it is not fully submerged with regular water flowing over it. If possible, disconnect the heater from the Spa Pack to avoid this.
Then, switch the power back on and turn the jets on full for 10-15 seconds and then turn them off quickly. You should see at least a small amount of air bubbles coming out. Wait a few seconds.
Next, turn the jets on for 20-30 seconds and then turn them off again. You will see more air bubbles come out. Again, wait a few seconds
Once again, turn the jets on and off for 30 to 45 seconds. At this point you should see a huge explosion of air bubbles coming out of the jets and you should have freed the trapped air. Forcing it round the pipes and out through the jets.
Keep running the jets until you see no more air bubbles coming out and just the regular flow of water.

Pay attention to the amount of air bubbles coming out of the nozzles. If you notice that the amount of air bubbles created is about the same (or worse, no air bubbles come out), stop the “burping” process immediately.

This means that your airlock problem is more complicated and requires more than just a “burping” procedure. If you continue burping at this point, it is possible that you will damage your Hot Tub pumps so best to stop.

Releasing the Air Lock from the Pump Area

If burping the Tub didn’t release the air, then the next step is to try and release the air lock from the pump itself.

To do so:

Turn off the main power supply to the Hot Tub.
Remove the front panel from the Hot Tub. This can usually be done with a screwdriver. Otherwise, refer to the user manual for specific instructions on how to open the front panel of the Hot Tub. You are trying to get direct access to the Hot Tub pumps.
When you remove the front panel, you will see most of the equipment and parts that make your Hot Tub work. What you are looking for is the pump. It’s pretty obvious that it is a pump and not a blower, spa control pack or ozonator, or indeed a filter!
On the pump, you will see two screw connections that attach pipe to it. One is the inlet and one is the outlet, they are usually white. These are Union Nuts.
Use your hands or a tool to loosen one of the nuts after you have found it. Keep loosening the nut until you feel or hear air escaping.
After a while you will notice water starts to flow. This is normal and this should mean that all the trapped air has already been released.
Tighten the union nut once again, switch the power back on and try to see if the jets are working.
Another quick tip there is that on the pump itself, on the circular face you will see usually a black screw that is about 15mm or 1/8” in diameter. This is a bleed screw and if you loosen this with a screwdriver, you can release any trapped air from the Pump. You should at first see air and when water comes out, the trapped air has been removed and you have “bled” the pump.

Call in the Professionals

If both of the above approaches fail, you should probably consider getting the professionals in. If necessary, contact an authorized service provider for your Hot Tub brand or a repair facility. Major Hot Tub manufacturers usually have a list of their dealers and service centers that you can view on their websites. Just as a side note, air locks are not normally something that is covered under warranty so expect to be charged a call out fee unless you have some form of a service plan in place. That said, a call out fee to get a pro to remove the air lock will be cheaper than having to replace a pump or a heating element as you burnt them out by running them dry!

Preventing Air Locks

It can be difficult to release an air lock in your Hot Tub, however, you can ensure that this does not happen again and try at all costs to prevent it. To prevent air locks from happening, you must ensure that you fill your Hot Tub properly. Yes, just sticking a hose pipe into the tub is apparently, not the right way to do it.

Experts recommend filling your Hot Tub through the filter. This is to ensure that the water fills the pipes, goes through the pump, filter, spa pack and then back out through the jets and fill the tub that way.

Seems straight forward enough and certainly makes lots of sense. So, when you are tempted to just dip the hose in and leave it for a couple of hours, think again!

Can I Help You?

If I can help you in any way I would love to hear from you. You can get in touch using the form below.

Thanks - Andi

Hi, Andi here. I own Buildahottub.com and also write all of the articles and info pages on the site. Some years back now, I built my own hot tub but struggled to find the information I needed. So, once my tub was complete, I started this website to help others in their own pursuit of hot tub and plunge pools DIY building information.

Today, I've helped over 1000 DIY customers just like you all over the world build hot tubs and pools. Have a good look around the site, there are lots of resources here. Please do get in touch if I can help you. - Cheers, Andi