Pentair Autotrol 255 User Manual (English)

Questions and Answers:

B
Brenda NelsonAug 20, 2025
Why is my Pentair Control Unit controller not drawing brine?
- R
  Rachel JacksonAug 20, 2025
  Several factors can prevent your Pentair Control Unit from drawing brine. These include low water pressure (adjust settings accordingly), a restricted drain line (remove the restriction), a plugged injector (clean the injector and screen), or a defective injector (replace the injector and cap). Also, valve disc 2 and/or 3 might not be closed due to foreign matter; remove the matter, check if the disc can close by pushing on the stem, and replace the disc if needed. Lastly, the air check valve might be prematurely closed; momentarily put the controller into brine refill (C8 cycle) and replace or repair the air check if necessary.
L
leegreenAug 22, 2025
Why is my Pentair valve not drawing brine?
- L
  Linda MillerAug 22, 2025
  If your Pentair valve isn't drawing brine, it could be due to several reasons. Low water pressure might be the cause, so set the pump to maintain 1.38 bar (20 psi) at the softener. A restricted drain line could also be the issue; change the drain to remove any restrictions. Additionally, the injector might be plugged (clean the injector and screen) or defective (replace the injector). Finally, the air check valve might be closing prematurely on the 255 valve or brine pickup tube; put the controller momentarily into brine cycle (C2) and replace or repair the air check if needed.
B
Becky EvansAug 25, 2025
What to do if my Pentair Control Unit has hard water leakage after regeneration?
- A
  Andrew PerezAug 25, 2025
  If you're experiencing hard water leakage after regeneration with your Pentair Control Unit, it could be due to improper regeneration. Try controlling the brine dosage setting and repeating the regeneration. Other possible causes include a leaking external bypass valve (replace the bypass valve), a damaged O-ring around the riser pipe (replace the O-ring), or an incorrect capacity (verify the appropriate brine amount and system capacity).
S
Stephanie HarrisAug 26, 2025
What causes a brine tank overflow in my Pentair Control Unit?
- B
  browntaylorAug 26, 2025
  A brine tank overflow in your Pentair Control Unit can be caused by several issues. The brine valve disc 1 might be held open by foreign matter; manually operate the valve stem to flush away the obstruction. Alternatively, valve disc 2 might not be closed during brine draw, causing brine refill; flush out any foreign matter holding the disc open by manually operating the valve stem. An air leak in the brine line to the air check could also be responsible; check all connections in the brine line for any leaks. Additionally, an improper drain control for the injector or a drain control clogged with resin or other debris can cause this.
J
Joseph PetersonAug 28, 2025
Why does my Pentair Control Unit regenerate at the wrong time of day?
- M
  megan77Aug 28, 2025
  If your Pentair Control Unit regenerates at the wrong time, the controller might be set incorrectly. Correct the time setting according to the instructions.
W
William SmallAug 30, 2025
What to do if my Pentair Control Unit will not regenerate automatically?
- M
  meyermariaAug 30, 2025
  If your Pentair Control Unit is not regenerating automatically, check if the AC transformer or motor are connected and connect the power if needed. If they are properly connected, the motor may be defective and need to be replaced.
S
Steven HarrisAug 31, 2025
What to do if my Pentair Control Unit system is using more or less salt than brine setting?
- H
  Heather WilliamsSep 1, 2025
  If your Pentair Control Unit system is using more or less salt than the brine setting, there might be foreign matter in the valve causing incorrect flow rates. Remove the brine controller and flush out any foreign matter. Then, advance the controller to the brine cycle (C2) to clean the valve; afterward, the controller will go to the "2nd fast rinse" cycle (C7) to remove any brine from the tank.
T
Tiffany ThomasSep 2, 2025
What causes intermittent or irregular brine draw in my Pentair system?
- V
  vargasalexandraSep 3, 2025
  Intermittent or irregular brine draw in your Pentair system can be caused by low water pressure, so set the pump to maintain 1.38 bar (20 psi) at the softener. Another cause is a defective injector, which would need to be replaced.
B
Bradley WilliamsSep 4, 2025
What to do if there is no conditioned water after regeneration in my Pentair Control Unit?
- M
  Michael LeonSep 5, 2025
  If you have no conditioned water after regeneration with your Pentair Control Unit, ensure there is brine in the brine tank. If the tank is empty, add brine to the brine tank. Also, the injector might be plugged, so clean the injector and screen. Another possibility is that the air check valve closes prematurely; put the controller momentarily into brine cycle (C2) and replace or repair the air check if needed.
S
scollinsSep 7, 2025
Why is my Pentair Control Unit backwashing or purging at an excessively low or high rate?
- B
  Bryan RandolphSep 7, 2025
  If your Pentair Control Unit is backwashing or purging at an excessively low or high rate, it might be due to an incorrect drain control being used. Replace it with the correct size controller. Another cause could be foreign matter affecting valve operation; remove the drain control and clean the ball and seat.

Pentair Autotrol 255 Specifications

General

Brand	Pentair
Model	Autotrol 255
Category	Control Unit
Language	English

Summary

Generalities

Scope of the documentation

Details the purpose and scope of the manual, including user requirements.

Release management

Tracks document revisions, dates, authors, and publication status.

Manufacturer identifier, product

Provides manufacturer details and the specific product model number.

Intended use

Specifies the product's intended applications and purpose for water treatment.

Abbreviations used

Lists common abbreviations and their meanings used throughout the manual.

Norms and Certificates

Lists applicable directives, standards, and available product certifications.

Procedure for technical support

Outlines the steps for requesting technical assistance and problem resolution.

Copyright and Liability

States copyright information and details limitations of manufacturer liability.

Scan & Service application

Describes a mobile application for accessing product information and service.

Safety

Safety pictograms definition

Explains the meaning of various safety symbols used in the manual.

Serial label location

Shows the location of the product's serial label for identification.

Hazards and Personnel Requirements

Details general hazards, material safety, and personnel qualifications for operation.

Hygiene and Sanitization

Covers sanitary issues, hygiene measures, and disinfection procedures.

Description

Technical specifications

Lists detailed technical specifications and ratings of the valve system.

Valve connections and electrical

Details thread types for valve connections and electrical requirements.

Performance flow rate characteristics

Graph showing flow rate vs. pressure drop for single valve operation.

Outline drawing

Illustrates the physical dimensions and layout of the valve.

Description and components location

Identifies and locates key components of the valve assembly.

Options available on the valve

Lists optional features and kits for the valve system.

Auxiliary Microswitch Kit Installation

Details installation of microswitch kits for electrical signaling.

Top plate mount microswitch

Explains the installation of a top plate mounted microswitch.

System regeneration cycle (8-cycles operation)

Describes the sequence of operations in an 8-cycle regeneration process.

Regeneration cycle diagrams

Illustrates water flow during different regeneration cycles.

Regeneration Sequence for Twin and Lockout Systems

Explains regeneration sequences for twin and lockout configurations.

Twin alternating systems

Details the regeneration process for twin alternating systems.

Twin parallel systems

Explains regeneration sequence for twin parallel systems (Refill off).

Twin parallel system refill options

Details twin parallel system regeneration with refill first option enabled.

Lockout "L" systems

Describes regeneration sequence for lockout systems.

System sizing

Recommendations

Provides general recommendations for system sizing.

Injector/DLFC/Refill flow controler-Valve configuration

Table mapping vessel size to valve components and flow controls.

Cycle time calculation

Explains automatic cycle time calculation by the controller.

Injector flow rates

Graphs showing injector flow rates vs. inlet pressure.

Injector flow rate charts

Flow rate charts for various injector types (J, K, L).

Resin exchange capacity (standard efficiency)

Table of resin capacity based on salt dosage for standard efficiency.

Resin exchange capacity (high efficiency)

Table of resin capacity based on salt dosage for high efficiency.

Installation

Safety notices for installation

Key safety warnings and requirements for installation personnel.

Installation environment

Guidelines for suitable installation locations and environmental conditions.

Mechanical installation

Mechanical installation guidelines and precautions for proper setup.

Outdoor Locations considerations

Specific considerations for installing the unit in outdoor environments.

Integration constraints

Required conditions for integrating the system into plumbing.

Block diagram and configuration example

Illustrates system layout and component connections.

Simplex and Twin systems configurations

Illustrates system configurations for simplex and twin parallel/alternating setups.

Valve connection to piping

Instructions for connecting the valve to the piping system.

Top-mounted valve installation

Guidelines for mounting and connecting the valve to the tank.

Installation compensation and lubrication

Proper compensation and lubrication guidelines for valve installation.

Electrical connections

Details electrical connections for the controller and sensors.

Interconnected systems and Twin wiring

Wiring diagrams for multi-simplex and twin parallel/alternating systems.

Bypassing instructions

Explains the function and installation of bypass valves.

Drain line connection

Instructions for connecting the drain line with air gap requirements.

Overflow line connection

Details how to connect the overflow line to the drain.

Brine line connection

Instructions for connecting the brine line to the valve.

Programming

Display overview

Explains the different elements and indicators on the controller display.

Display indicators

Detailed explanation of display elements like units and symbols.

Controller commands

Describes the function of each button on the controller interface.

Basic programming overview

Overview of the basic programming menu and general notes.

Basic programming 742/762 controllers

Step-by-step guide for basic programming on 742/762 controllers.

Regeneration time and day settings (742/762)

Setting regeneration time, days override, and day of week for 742/762.

Salt amount and capacity settings (742/762)

Setting salt amount, system capacity, and hardness for 742/762.

Basic programming 764 controller

Step-by-step guide for basic programming on 764 controller.

Time, day, and regeneration settings (764)

Setting time, day, regeneration time, and days override for 764 controller.

Salt, capacity, and hardness settings (764)

Setting salt amount, system capacity, and hardness for 764 controller.

Advanced programming overview

Introduction to advanced programming for 8-cycle softener systems.

Advanced parameter details

Details parameters P9-P12: units, clock mode, service interval, remote switch delay.

Advanced parameter details (cont.)

Details parameters P13-Pd: chlorine options, refill/draw rates, reserve, regeneration mode.

Cycle time programming

How to program specific cycle times for the softener.

Diagnostic codes and interpretation

Information on accessing and interpreting diagnostic codes.

Resetting the controller

Procedure for resetting the controller to factory default settings.

Commissioning

Water filling, draining and watertightness inspection

Procedures for filling, draining, and checking for leaks.

System startup and initial regeneration

Steps to initiate the system and start the first regeneration.

Brine tank initial fill and refill cycle

Instructions for initial brine tank fill and priming the refill cycle.

Drawing water from brine tank and tips

Procedure to draw water from brine tank and additional commissioning tips.

Sanitization and System disinfection

Procedures for sanitizing and disinfecting the water softener system.

Hypochlorite and Electro chlorination disinfection

Details using hypochlorite and electro chlorination for disinfection.

Operation

Recommendations for operation

Recommendations for optimal operation and salt usage.

Manual regeneration procedures

Instructions for initiating manual regeneration cycles and advancing/canceling.

Automatic regeneration modes (twin system)

Automatic regeneration modes for twin systems (764 only).

Parallel systems regeneration modes

Explains regeneration modes for parallel systems (P16=0, P16=1).

Parallel systems regeneration modes (cont.)

Describes P16=2 and P16=3 regeneration modes for parallel systems.

Maintenance

General system inspection

Annual inspection checklist for the system's components.

Water quality and mechanical checks

Checking water quality and performing mechanical component checks.

Regeneration test

Performing tests to verify regeneration function.

Recommended maintenance plan

Schedule for maintenance of various components over 5 years.

Recommendations on Parts, Lubricants, and Maintenance

Advice on spare parts, lubricants, and general maintenance instructions.

Cleaning and maintenance procedures

First steps and detailed procedures for cleaning various components.

Troubleshooting

ERR 1-3: Controller and camshaft errors

Troubleshooting for controller power, frequency, and camshaft rotation errors.

ERR 4 and brine tank issues

Troubleshooting camshaft position errors and brine tank overflow.

Water flow and regeneration issues

Diagnosing water flow problems and dripping water after regeneration.

Hard water, brine draw, and timing issues

Resolving hard water leaks, brine draw failures, and incorrect timing.

Conditioned water, flow rates, and overflow issues

Troubleshooting no conditioned water, abnormal flow rates, and brine tank overflow.

Spare parts

Valve parts list

Illustrated list of valve components and their part numbers.

Valve Parts List Details

Detailed listing of valve assembly parts and quantities.

Valve Parts List Details (Continued)

Continuation of the detailed valve parts list.

Options and special kits

Lists controller options and special kits available for the system.

Meter adapter parts

Parts list for meter adapter kits.

Piping boss and manifold parts

Lists various piping boss and manifold components.

Bypass and connection parts

Lists parts for bypass body and various connection adapters.

Interconnecting kit and connection parts

Lists parts for interconnecting kits and connections.

Valve installation kits

Lists components included in valve installation kits.

Disposal

Disposal guidelines

Guidelines for environmentally responsible disposal of the device.

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Pentair Autotrol 255 User Manual

Table of Contents

Questions and Answers:

Pentair Autotrol 255 Specifications

Summary

Generalities

Scope of the documentation

Release management

Manufacturer identifier, product

Intended use

Abbreviations used

Norms and Certificates

Procedure for technical support

Copyright and Liability

Scan & Service application

Safety

Safety pictograms definition

Serial label location

Hazards and Personnel Requirements

Hygiene and Sanitization

Description

Technical specifications

Valve connections and electrical

Performance flow rate characteristics

Outline drawing

Description and components location

Options available on the valve

Auxiliary Microswitch Kit Installation

Top plate mount microswitch

System regeneration cycle (8-cycles operation)

Regeneration cycle diagrams

Regeneration Sequence for Twin and Lockout Systems

Twin alternating systems

Twin parallel systems

Twin parallel system refill options

Lockout "L" systems

System sizing

Recommendations

Injector/DLFC/Refill flow controler-Valve configuration

Cycle time calculation

Injector flow rates

Injector flow rate charts

Resin exchange capacity (standard efficiency)

Resin exchange capacity (high efficiency)

Installation

Safety notices for installation

Installation environment

Mechanical installation

Outdoor Locations considerations

Integration constraints

Block diagram and configuration example

Simplex and Twin systems configurations

Valve connection to piping

Top-mounted valve installation

Installation compensation and lubrication

Electrical connections

Interconnected systems and Twin wiring

Bypassing instructions

Drain line connection

Overflow line connection

Brine line connection

Programming

Display overview

Display indicators

Controller commands

Basic programming overview

Basic programming 742/762 controllers

Regeneration time and day settings (742/762)

Salt amount and capacity settings (742/762)

Basic programming 764 controller

Time, day, and regeneration settings (764)

Salt, capacity, and hardness settings (764)

Advanced programming overview

Advanced parameter details

Advanced parameter details (cont.)

Cycle time programming

Diagnostic codes and interpretation

Resetting the controller

Commissioning

Water filling, draining and watertightness inspection