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How To Fix Hot Tub Flow Errors

What is a hot tub flow error?

A hot tub flow error indicates that there is a problem with the flowing of water through the hot tub heater. Some of the most common hot tub error codes are FLO, FL1 or FL2, and are picked up by flow or pressure switches. The most common causes for this are a dirty or damaged filter, low water levels, air in the pipework or a faulty pump or sensor..

What are hot tub flow switches?

Hot tub flow switches and pressure switches monitor the flow of water through your tub and act as a safety device, turning the heater off if the water flow is interrupted. This safety mechanism is built into hot tubs to prevent damage to your heater and other equipment.

We've put together this troubleshooting guide to help you diagnose and fix your hot tub water flow issues without the need for a hot tub technician.

What is the difference between flow error codes?

The exact error code you will see may vary between manufacturer and model. You should always consult the manufacturers instruction booklet for specific information, however generally it is found that:

  • FL1 hot tub code – indicates that there is an error with the flow switch and it is stuck in the open position
  • FL2 hot tub code – indicates that there is an error with the flow switch and it is stuck in the closed position
  • Flo hot tub code – indicates there is an issue with the water flow

Hot Tub Flow Error Troubleshooting Checklist

There are several checks you can perform to try and resolve your hot tub flo errors including:

1. Does the water 'kiss the pillows'?

The hot tub water line should be touching the bottom of the pillows when no one is in the spa. If your hot tub does not have pillows, then it will have a 'waterline' indicator somewhere on the shell or the filtration skimmer. Ensure that your hot tub water line meets the minimum requirements and top up if necessary. 

2. When did you last clean the filter?

If your filter is dirty it could be restricting the flow of water around the hot tub. Every 10 weeks you should clean and soak your hot tub filters overnight. Whereas, on a weekly basis, you should always try and 'rinse' the large debris out of your filter.

For more information, take a look at our hot tub filter cleaning guide.

3. When did you last get a new filter?

Your hot tub filter may be clean, but with every use, the fibres break down restricting the flow of water.

Hot tub filters should be replaced every 12-18 months and we recommend always having two filters so you can rotate them during cleaning. It is also important to  purchase genuine hot tub filters to ensure that your tub runs more efficiently as this will give you a better circulation of water.

4. Have you recently refilled/changed the spa water?

If you recently filled the spa, where did you put the hose during filling? When refilling a hot tub, you need to put the hose pipe down the filter housing so that the water fills the internal pipework first. If you simply 'drop' the hose into the main spa area it may have been backfilled - causing airlock. Make sure the water is at the required water line before you turn the hot tub on.

What is a hot tub airlock?

An airlock is a large pocket of air trapped within the pipes of your hot tub. It will reduce the circulation of water as it will not properly flow through the hot tub heater.

5. Are all the jets/air controls switched on and are all diverters in their central position?

Closing off these controllers can prevent the flow needed for filtration and therefore cause a problem. Ensure that these are open along with the jets in all seats.

How to fix hot tub flow errors

The following solutions are recommended to try and resolve your hot tub flow errors:

Solution A: Increase the hot tub water level

If the water level is not correct, top up your tub with more water. Switch off the power and remove the filters. After 20 minutes, switch the power back on and run the spa/jets without the filters to see if it clears the flow issue.

If the flow clears, switch off the power again, replace the filter and then switch on the power. Then, if the flow issue returns you know the issue is with the filter and it will need replacing.

Solution B: Remove an airlock in your hot tub heater

As a first step we recommend the following actions to remove an airlock in your hot tub:

  1. Make sure all jets are open
  2. Run the spa pumps without filters and see if it clears

If this does not work try the following:

  1. Switch the spa off
  2. Run a hose pipe to your hot tub, ensuring you place the pipe down the filter housing to try and push the air through

If the flow issue does not clear after solution A or B then it is possible you either have a faulty pump that is not pushing the water through or a faulty pressure/flow switch. If this is the case, we recommend calling a technician to help solve your hot tub problem.  

Alternatively, talk to our team of experts and book a hot tub service here.

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