How do I Troubleshoot a Pentair 320 Chlorinator?

The Pentair 320 model chlorinator is an in-line device used to inject chlorine into the water of a swimming pool. It is installed in the "return" line of your pool's filter plumbing, connected to the return pipe with a simple tee fitting. In this type of chlorinator, chlorine tablets are placed directly into the canister and are dissolved by the pool water as it flows through the chlorinator.

Clear water in a swimming pool.
Keep your Pentair chlorinator in top working condition to provide a properly sanitized pool.

All chlorinators require regular maintenance and troubleshooting in order to operate at full capacity. To maintain the Pentair 320 chlorinator and others similar in design, the screen at the bottom of the device is cleaned, the check valve is examined for proper flow, and the body is bled of air.

A Pentair 320 chlorinator.
credit: Pool Supply World
An in-line chlorinator, such as the Pentair 320, automatically feeds chlorine to the pool.

Remove the chlorinator's lid. Grasp any tablets still in the chlorinator with tongs and remove them. Wearing rubber gloves or using tongs, reach down into the chlorinator to retrieve the black screen resting at the bottom of the chlorinator.

Step 2

Wash the screen with water to rinse off any debris caught in the screen. To reinstall, apply downward pressure on the screen as it sits inside the chlorinator until you hear it snap into place.

Step 3

Inspect the check valve: Unscrew the small check valve assembly connected to the base of the chlorinator body. Pull the black hose off of the check valve assembly to free it completely. Shake the valve assembly and listen for a clicking noise. A clicking noise at every shake indicates the valve is clean and water is able to flow through it freely. No noise indicates the valve is either clogged or broken and should be replaced or sprayed with a water hose to dislodge any debris stuck in the valve. Reconnect the hose to the valve and screw the valve back into the chlorinator.

Step 4

Reassemble the chlorinator: With the lid of the chlorinator removed, turn on the pump so that water begins to fill the chlorinator body. When water begins to flow over the top, screw the lid back on. This purges air from the chlorinator lines and eliminates the risk of the system becoming vapor-locked.