Loud bang from Autotrol Water Softener During Regeneration November 17, 2016 16:19


Did somebody just fire a shotgun in the basement or was that the water softener!?

If air is allowed to get into the softening tank of an Autotrol softener, you can end up with some pretty loud noises during the regeneration. Enough to wake you from your sleep. The issue is almost always caused by a failure of the air-check mechanism.  Before we get into the details, here's a little background:

When your Autotrol Softener goes through a regeneration, one of the cycles is the Brine Draw followed next by the Slow Rinse. In Autotrol-speak these are referred to as cycles 2 and 3. The purpose of cycle 2 is to draw the brine solution into the softening tank, and then cycle 3 slowly pushes this important brine solution through the resin bed.

Once all of brine solution has been drawn out of the brine tank an air-check valve prevents the softener from accidentally drawing air into the tank. If this valve fails, you end up with air in the tank and this air is the cause of the loud noises that are waking up the kids.

One complication of troubleshooting this, is that an Autotrol softener can have the air check in one of two places:

Location 1:  The Sight Glass

On the side of your Autotrol softener there is a clear site glass.

autotrol air check sight glass

This sight glass may or may not contain a small plastic marble. If it does, this marble is what acts as the air check. You'll want to take the sight glass apart and make sure that the marble can move freely and that it can seat properly at the bottom of the sight glass.

Location 2:  The Foot of the Safety Float

Your brine tank is where you add the salt to your softener. Inside most brine tanks you'll find a 4" tube with a lid on it. Take the lid off this tube to reveal the safety float. The safety float has two purposes:

  • it has a sort of toilet tank floater that is actuated if the softener tries to add too much water to the brine tank (flood prevention)
  • it has a pickup at the very bottom where the brine solution is sucked into the softener

If your Autotrol softener does not have a floating marble air check in the sight glass it will certainly have one in the pickup. The pickup is at the bottom and is usually a cage of some kind. Inside the cage you'll find the floating marble. Here are some commonly used float assemblies showing the pickup at the bottom:

water softener safety float pickup aircheck

To service the air check, you will want to detach the brine line from the safety float - it usually attaches at the top. Then the safety float can be pulled out. A few of them are attached to the side of the brine tank with a nut - if that's the case you'll need to undue this first. Once the safety float is removed, run the bottom pickup area under hot water and make sure the marble can move freely.

Once you're all done put everything back together, paying special attention to the connection point between the brine line and sight glass, and the brine line to safety float. If either of these are not air tight, the brine draw won't work. Then force a regeneration (on most softeners this is done by pressing and holding the 'regen' or 'next cycle' button). Let the softener run it's course and see if the gun-shot noise is gone.