Knowledge Base:  
Autotrol 155 or 255 - Injector Size / Color - Why BLUE is sometimes used on 8 inch tanks
Last Updated: 01/28/2019
Often you will find a Blue Injector ( AP28F-BB, 1032971 ) installed in an Autotrol Valve used on an 8 inch diameter tank,

Most valves come from manufacturer with the BLUE injector installed ( since most common residential tanks are 9" or 10" diameter ).

And it's not "necessary" to down size ( White Injector has smaller internal holes for reduced flow rate ).
The slightly large internal ports ( holes ) of the BLUE injector will allow better / more water flow through the Valve and Tank.
And less likely to "clog" internally.

And this is beneficial when the Valve is used on well water that has lower pressure ( like 20 - 40 psi, or even 30 - 50 psi ).
It just makes sense to use the next size up, for better flow rate during the 50 minute Brine Rinse ( suction and rinse ) Cycle.
You don't want to leave any of the Salty Water in the Resin tank. You want it completely rinsed through and out of the tank.
That is the main reason for different Injector Size / Colors.
The larger the tank ( diameter ) the more FLOW is required to properly suck in the Salt / Brine water, and Rinse if all out, in the normal 50 minute cycle time.

It's been common practice in South Florida to do this on Well Water ( use BLUE instead of WHITE ), as the common above ground shallow well jet pumps often only reaches 40 or 50 psi.

But since you only "need" the White Injector, when pressure is good ( 50+ psi ), and all "city" water, and most submersible pumps provide this,
We install the Injector size / color as specified by the manufacturer in all Autotrol 155 ( replacements ), which is the 255.
When you order the APK5 or AP24NC.
And also, the Newer "logix" controlled versions, use matching sized injectors based on
tank diameter too.

Model 155...........................................................................................Model 255

How do I know if I have an Autotrol 155 ( 1550-TC ) or a model 255 Valve?

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.

Please Rate the Usefulness of this Article


Related Articles
 > # 1 FAQ = High Water in Brine Tank - Problem -Softener does not remove the water from my salt tank or overflow
 > 3 ways the Backwash cycle could be "blocked" in an Autotrol system
 > 440 - 460 Output Gear Repeatedly Breaking After Replacement.
 > 440 or 440i - Which Timer Assembly Do I Have - How to Tell
 > 440 or 440i or 460TC - Cycles controlled by the Camshaft used
 > 440 Timer Rebuilding / Repair / fix Guide
 > 440 Tripper Arm Gear Repeatedly Breaking After Replacement.
 > 440 Upgrade to 760 metered demand Logix Timer - How?
 > 440i motor replacement guide
 > 440i Sticking in Backwash or Brine Refill
 > 460i Timer RESET if it is Regenerating EVERY NIGHT
 > 460TC or Logix 740 - Which Timer Replacement is Best?
 > 460TC Timer Off Set When Multiple Valves Used
 > 740 and 760 Logix Timer Programming Instructions
 > 940 and 960 Timer Obsolete - Replacement Options when used on 255 Valve
 > Air Check - Ball seated or dropping early during the BRINE/SLOW RINSE -Autotrol 155 or 255 Series
 > Air Check Autotrol Old 36F or Newer Style - How to Tell - How to Clean
 > APK5 - 255 Upper Valve Module - Brine Suction / Brine Tank Overflow after replacing the Top part of the Valve
 > Autotrol 155 ( 1550-TC ) Valve Leaks - How to solve them
 > Autotrol 155 or 255 - How to Tell Which You Have
 > Autotrol 155 or 255 High Water in Brine Tank - Problem No Suction or Overflowing
 > Autotrol 155 with 440 Upgrade to 740 Day timer or 760 metered demand Logix Timer - How?
 > Autotrol 163 or 168 Rebuild Kits
 > Autotrol 163 or 168 replacement Valve Recommendation is Performa 263 or 268
 > Autotrol Date Codes - Serial Numbers
 > Autotrol Valve Flow Rate Problem - Either Resin in Tank or Valve Discs not Opening Enough
 > Autotrol Valve Leaking to Drain after Replacing Valve Discs
 > Backwash Plug and Injector Cap Removal Tool
 > Backwash Plug Number - Autotrol How can I tell what number of backwash plug I need?
 > Brine Refill after Autotrol 155 or 255 Repair - Purge Air from the Valve head, Brine line & Air Check
 > Brine Refill Problem - No water in salt tank - Autotrol
 > Brine Tank Assembly - Questions, Answers, Video Link
 > By Pass - Autotrol Old Style - How to Use
 > By Pass - Autotrol Old Style - Leaking When Connected to New Autotrol Valve
 > Calender Over Ride setting for 760 and 762 Logix Timer Programming
 > Can an Autotrol 255 valve be converted from softener use to filter ( carbon ) use?
 > Err 3 on 740,742,760, or 762 Logix Timer
 > Fittings Measurements Different Then Expected ( 1/4 and 3/8 fittings )
 > Freeze Damage to Air Check Body Autotrol 255
 > Gears, Housing, Motor Inside the 460i and 460TC timers - What is the difference?
 > Hard water when Autotrol Valve is working and using Salt properly - By Passing the RESIN?
 > How To Repair A Logix Controller - Replacing Back Up Capacitor on the Board
 > Media ( Resin, Carbon, Greensand, Calcite, etc ) Getting Up Into the Valve Head - Causes
 > Model 172 and 180 are Obsolete - Commercial Autotrol Valves and Parts
 > Model 360, 363 and 368 Autotrol Valves and Parts
 > NovRam, 460i and 460TC timers - What is the difference?
 > Performa Valves Keep Breaking 440i Timers - Solution is...
 > Pump Pressure Low or Cycles OFF and ON ( Well Water )
 > Screen shows 1.1 on 740,742,760, or 762 Logix Timer - Button Test Mode
 > Setting Time of Day with the Autotrol 440 Tripper Arm Gear 99F
 > Tank Diameter - How To Measure and Why It Matters
 > Technetic - Series 1010 Bypass Valve
 > Technetic 1000, Plus, 1100i replacement Valve Recommendation
 > Top Distributor Modifications - MD1203 used with Performa 263 and 268
 > Turbulator - Why Would Someone Use This Over A Standard Bottom Distributor Basket / Riser Pipe?
 > Water Soft WSCB-32D water softener = Autotrol Valve Links