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Autotrol 155 ( 1550-TC ) Valve Leaks - How to solve them
Last Updated: 04/23/2015
Customer writes:
My Autotrol 1550-TC unit leaks water from the control valve body.
Should this be rebuilt or replaced to solved the leaking?

Leaks are easy to fix.
Either the o-rings, or flapper valve discs need to be replaced.
And the upgrade, APK5, would solve all leaks except those coming from the tank adapter, or your by pass connection.

If the leak is from under the valve body and above the tank adapter, it is the 6 orings usually. And not usually the "body" itself.
The o-ring ( little one in the front ) for the brine port could also be leaking - it is one of the orings included in this kit:

Note there are several places the valve body can leak, so be sure to look above any water, in case the "source" is a cap, or the flapper valve discs ( under the top plate ).

The Brine Control Dial could be leaking.

So, there are 3 - 4 areas of the Valve that can develop a small leak.
They may not show an outward water leak, as the Brine section is not under pressure.
Only during Brine Refill is there any out flow.
You can try blocking flow ( at the Air Check outlet ) and put the Valve into the Brine Refill cycle, and perhaps you could force the leak to drip some water to determine the source.

Replacing the orings, or the tank adapter or the brine control dial, might be the solution.

Complete new Valve head replacement would also be a solution to this issue.
And the newer 255 valve can all be connected directly to the older 155 By Pass or Piping Boss / yoke ( whichever you have ).

The Series 155 was replaced by the Series 255 late 1995 ( early 1996 ).
An easy way to tell the difference is, the brine control ( salt dial ) is located on the front ( just beneath the timer housing ) on the 155 and it has been relocated to the right side ( looking from the front ) on the 255.

Another noticeable difference is the Injector Cap, and Injector Screen/Cap are the size of a quarter on the newer 255. They are about the size of a dime on the older model 155.

Note: The Brine Control and the Backwash Flow Control plugs are identical in size on both the 155 and the 255. However, another difference is the location of the Backwash Flow Control Plug ( 25F )is on the right hand side ( looking from the front ) on the 155 and has been moved to the left side on the 255.

Autotrol Series 155 Valve Autotrol Series 255 Valve

(click image to enlarge)

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