Hot Tub Maintenance & New Spa Brands

Hot Tub Pump Not Working – Air Lock

Sometimes after a water change, the pump will not work on a hot tub for no apparent reason.  The pump may hum, but it does not appear to be moving water. The pump shaft may be spinning, but if there is air in the line, then it cannot properly prime the pump. This air pocket or air lock needs to be purged from the plumbing so the pump can function normally.

Channel Lock Pliers hot tub repairThe best way to loosen one of the pump unions to remove the air lock is with channel locks or large pliers.  If those are not available, this enterprising tech in the video uses a simple hammer and screwdriver. When using that method to loosen the large nut, be careful not to hit it too hard and crack the plastic union.

Many times these unions are just hand-tightened with good pressure, but sometimes pliers are used to tighten them further. No need to overtighten these as long as there is no water leaking.

If the spa has an air lock, an error message on the topside control panel may show a FLO error or similar message indicating there is a flow problem and the spa cannot heat.  dr or drY indicate a dry heater with an air pocket.  OH means the heater actually came on and tried to heat and ended up in an overheat condition. All of these error codes reflect back to the possibility of trapped air in the system.

hot-tub-pumpSome spas may have a bleed valve, or some pumps may have one, but cracking the union and then re-tightening it is a quick way to purge the water if you have big pliers.

Other guys say to use the bleed screws on the pump, but people confuse those with freeze plugs which are designed to be removed from the pump only when storing the spa empty over the winter to protect the pump from cracking in places.  If you use the freeze plugs to try to purge water, you will have a wet mess on your hands before the air is purged.

Simply placing  a towel or rag under the pump union and slightly opening it should produce the hissing sound of trapped air escaping followed by a small squirt of water that reminds you it is time to close the union now.

Prime the Pump – Clear the Air Pocket
Another method to clear or purge air from the system if the spa was already in use and this just happened is to stop and start the pump a few times.  Note that if there is a leak in the system, then that can cause air to enter as well.  In that case, check in the spa cabinet for any leak(s) that may need to be addressed/repaired.

For safety, always turn of the main breaker and power to the spa when working on the spa or call a qualified technician for assistance as working with electricity or working on any appliance can be dangerous.

A gasket or o-ring inside the pump union keeps the water from leaking out, so no additional silicone, glue or teflon tape etc. are needed as you want to be able to remove the union whenever you need to service the pump.  Be sure not to remove or crimp the little o-ring inside the union, you should not have to open it that far.

After a Water Refill – Priming Mode
Balboa control systems often start up in Priming Mode.  We always stare blankly at the spa for 4 minutes wondering what priming function is taking place. It always sounds real quiet, but surely this 4 minute priming mode is somehow getting the pump ready to turn on, right?  Nope – actually, those are just 4 wasted minutes in our lives, because the spa is waiting for you to manually prime each pump by turning on each pump button individually to assure they are moving water smoothly without any air pockets.  It is up to the user to manually push each button to test every pump and assure they all work – verify each pump is primed one at a time.

If one has an air pocket, then the pump can be started and stopped several times in a row (by pushing jet button) in order to try to clear the air pocket that way before needing to result to “cracking the union” open a bit in order to purge air that way as described above.

Never run a pump without assuring it is fully primed (full of water) for more than about 2 minutes to avoid damage or an overheat condition.  When priming a pump, use the high speed of a two speed  pump.  If you run out of time in the 4 minutes allotted for manual priming and you still have not verified all the pumps are primed, turn the spa off at the breaker immediately and start over. If repeated attempts (hours apart) still cannot get pumps to prime, you can wait overnight and just let the spa sit.

Sometimes that is enough to get water seeping into any crevices and the priming the next day may go better.  Otherwise, opening the union slightly may help get air out. Finally, there really may be a problem in which case you can consult with a qualified spa tech.

Also be sure you are troubleshooting the correct component. For example, if there is no or low water flow the issue can be caused by many things besides an air lock including a dirty filter, partially closed service valve, or an actual obstruction in the plumbing line.

Hot Tub Tools

spa vacSome hot tub repair tools to have on hand include large pliers or channel locks.  These are handy when the heater unions or pump unions need to be opened. Be sure they will span at least a 2″ plumbing connector.  In the absence of proper channel locks, you can try the old hammer and screwdriver method. Also be careful when using cheap screwdrivers that the plastic backing doesn’t break away when you hit it with a hammer.

Other hot tub tools include jet removal tools, PVC glue and primer, a hack saw for cutting pipe that needs to be re-glued or repaired, Phillips head screwdriver for opening the spa pack and accessing the spa electronics and circuit board and a variety of other tools.

Hot Tub Problems with the Pump and Heater

hot tub top viewThe first reaction to the air lock problem may be that “my heater does not work”, but it is actually the pump that is not moving water through the heater. Heaters will not receive power during this condition because of the protective circuit in the hot tub.

Older hot tubs use a flow switch or pressure switch to detect proper water pressure inside the heater manifold, while newer spas have sensors built right into the heater that monitor the water volume and pressure inside the heater tube.  So if the heater is not working, it may be because the pump is not working.

If the pump is getting power, or even humming but no water is moving, there could be a problem with the impeller or other pump part, or there could be an air lock.  On new refills, chances are it may be an air pillow that needs to be purged.

Sometimes the system will automatically clear the problem with repeated manual attempts to prime the pump, while other times opening the main circulation pump union a bit and then closing it again may solve the problem by bleeding trapped air out of the line.

Be sure you are purging air from the main circulation pump or filter pump if your problem is that the spa will not heat and water will not filter or circulate on Pump #1 and not working on the wrong pump.  The main filter pump is connected by hoses or pipes to the filter canister and spa heater.

No or Low Water Flow

pump wet endOther problems that can contribute to no flow or low flow from the water pump is that the impeller is frozen or stuck, or even broken.  The filter may be clogged and dirty. Removing the filter with the spa off and then turning the spa on again should clear the problem.  Be sure to never operate the spa without a filter to avoid contaminants and debris from getting into and damaging the pump. Use a clean filter or clean the existing filter.

Sometimes if the water level in the spa is too low, a sucking sound can be heard as air is sucked into the filter canister. This is a sure way of getting an air pocket inside the spa, so don’t operate the spa until the proper water level is attained by filling the spa with a garden hose.

A tip is to fill the spa from the filter canister with the hose instead of leaving the hose dangling in the foot well of the spa.  This introduces water straight into the plumbing line and lowers the chance of establishing an air pocket in the hose or pipe.

If you have any service valves, especially the slice valves, be sure they are all the way open (up) as sometimes they can get stuck in the half-down position and reduce water flow.

Also, your spa should have the appropriate voltage at the supply side.  Spas don’t work too well during brown outs or low voltage conditions.  Running a spa with improper wiring or low voltage over a period of time can damage pumps and equipment.

Hopefully you were able to solve your air lock problem by purging air from the system. To prevent air locks, fill the spa straight into the filter compartment.

Read more tips and find the hot tub repair tools, supplies and accessories you need at America’s fastest growing online hot tub supply shop, Hot Tub Outpost –

Enjoy your spa!

Pump humming, but no or little water flow? Your spa may have an air lock.