Johnson Controls System 350 Controllers

Johnson Controls System 350APPLICATION MATRIX (click to enlarge chart)

Johnson Controls Electronic Boiler Reset Control

Upgrade to the advantages of a solid state temperature reset controller at a reasonable price!

Reset controls provide the optimum water temperature for heating by balancing the delivered hot water temperature to the conditioned space in proportion to the outside air conditions. The colder it gets outside, the hotter the setpoint becomes inside. The outdoor sensor signals the control which adjusts the supply water temperature. The reset ratio, because it’s electronic, can be set anywhere between 1:5 and 3:1. The A350R is compatible with other System 350 plug-in components so you can add staging, power and display.

NOTE: The built-in outdoor cutoff feature is a big money saver because it allows you to select an outdoor temperature where you don’t feel the building needs to be heated. Once it gets to the outdoor cutoff temperature the occupants can fiddle with thermostats all they want without getting any unnecessary heat! This feature alone makes it an ideal replacement for existing mechanical reset controls, such as the T475 and T678.


  • Power: 24Vac
  • Reset ratio: 1:5 to 3:1 (indoor:outdoor)
  • Relay: SPST, 4A
  • Differential: 1 to 30°F
  • Sensors: (1) indoor, (1) outdoor (included)
  • Warm Weather Shutdown: OFF, 60°F, 64°F, 68°F, 72°F (jumper selectable)
  • Setback: 0 to 30°F (clock terminals included)
  • Min. Supply Temp.: 50 to 160°F


  • Field-adjustable ratio
  • Automation or time clock setback
  • Field-adjustable temperature, offset, differential and setback
  • DIN rail or wall mount
  • Outdoor temperature cutoff
  • LED indication of “ON” and “SETBACK”
  • Minimum supply temperature setting
  • Outdoor sensor can be mounted anywhere with standard wiring
Part # Reset Controller  
EN-EWC10-0 5 Module Locking Enclosure Call... Add to Order
EN-EXP101-0 5 Module Expansion Enclosure Call... Add to Order
FM1D20A-24 External Setback Clock Call... Add to Order

Johnson Controls Humidity Control Module


  • computer rooms
  • clean room
  • pharmaceutical manufacturing process
  • space humidity
  • humidity monitoring and display
  • high/low humidity alarm indication

Johnson Controls Humidity Staging Module

multiple staging for humidification/dehumidification of clean rooms, computer rooms, or space humidity control

Johnson Controls Humidity Display Module

The S351 Humidity Stage Module is used in conjunction with the W351 Humidity Control to add multiple staging capability. Up to five S351’s can be added to the W351 via the 5-pin plug-in connector. Optional cables allow for remote display.

Part # Display Range Cable Length  
WHA29A-600R - 3 ft. Call... Add to Order
WHA29A-603R - 25 ft. Call... Add to Order
WHA29A-604R - 50 ft. Call... Add to Order

Johnson Controls Humidity Sensors for W351

These Humidity Transmitters are used in conjunction with the W351 Humidity Control to provide on/off action for humidification and/or dehumidification equipment.

Part # Mount Descr  
HE-67N3-0N00P Duct Humidity Sensors for W351 Call... Add to Order
HE-67S3-0N0BT Mount Humidity Sensors for W352 Call... Add to Order

Johnson Controls Pressure Control Module

The P352 Pressure Controller is an automatic reset electronic pressure control with SPDT relay output and LED indication. The P352 is designed with a selectable direct/reverse switch, adjustable differential, and replaceable pressure transmitters. Wall- or DIN-rail mounting.


  • condenser fan cycling
  • compressor unloading
  • high pressure indication

Output: SPDT, 10A Input: 24Vac

Johnson Controls Low Pressure Control Module with Modulating Output

Now you have an A350 Series module for very low pressure applications!

Use for low pressure (inches water column) applications when you need a proportional output. Both models shown have a selectable 0–10Vdc or 0–20mA output. Use separately or expand your options with the R353 signal input and S353 staging modules (see System 350 Accessory page).

Johnson Controls Pressure Staging Module

The S352 Stage Module is used in conjunction with the P352 Pressure Control to add multistage capability. Up to five S352’s can be added to the P352 via the 5-pin plug-in connector.


  • multiple staging of condenser fans
  • multiple compressor unloading

Johnson Controls Pressure Sensor for P352


  • direct mounting
  • compact size and light weight allow for mounting by pressure port alone
  • wiring harness required, call us for options
Part # Range Signal  
P399BAC-1-200C 0-500 psi 0-5Vdc Call... Add to Order
MR-C-S-C 0-500 psi 0-5Vdc Call... Add to Order

Johnson Controls System 350 Modular Electronic Controllers

Until now the dependability, accuracy and remote sensing capabilities of electronic controls were expensive and complicated. Now, you can enjoy the benefits of electronic controls without paying for features you don’t want or need. If you need them later, just add them. Display. Transformer. Stage Adders. System 350 can be tailored to meet the application requirements of each customer.

Johnson Controls designed these controls with the convenience of snap-together modularity. A unique five-pin connector makes it possible to add modules quickly and easily without interconnecting wiring. System 350 units feature DIN rail and wall mount capabilities combined in a single case.

Johnson Controls Electronic Temperature Control Module

At the heart of the System 350, the A350 temperature control has remote sensing capability up to 800 feet. And it’s accurate … to within ±1°F. The A350 Series Controllers are automatic reset electronic temperature controls with a SPDT relay output and LED indication—the LED is illuminated when the relay coil is energized.


  • Heat/Cool switch
  • 1 to 30°F adjustable differential
  • Interchangeable temperature sensors
  • Selectable direct/reverse acting


  • Frozen/refrigerated food cases
  • Space temperature control
  • Cooling tower control sensors
  • Beverage coolers
  • Chiller staging

Johnson Controls Electronic Cooling Control Module

The A350E is an on/off electronic cooling only control with SPDT, 10A relay output and LED indication. Besides being a cooling only control, the A350E has two features that differentiate it from the A350: an adjustable minimum setpoint, and short/open circuit protection.


  • minimum setpoint selection allows greater control over the cooling system
  • wide adjustable differential of 1–30°F enables the user to match equipment cycle rate and/or sequencing for a given application.

Johnson Controls Electronic Proportional Plus Integral Temperature Control Module

The A350P Series Controllers are electronic temperature controls with proportional 0–10Vdc or 0–20mA output. Proportional plus integral control is an option to hold setpoint regardless of load shifts on the system.


  • surface or DIN rail mounting
  • minimum output adjustment
  • field selectable proportional only or proportional plus integral control
  • ten segment LED displays percentage of output signal
  • heat/cool switch allows for reverse or direct acting output

Johnson Controls Temperature Display Module

The D350 Display Modules receive their power, sensor and setpoint information from the A350, W351 or P352 sensing modules. A three-digit, LCD (liquid crystal) display gives continuous readout of the sensor temperature, humidity or pressure.

Johnson Controls Staging Module

The S350 Staging Modules are used in conjunction with the A350 temperature controls to add multiple stage capability, receiving their power, setpoint and sensor input from the A350 control module. It has a SPDT output relay and three adjustments, including offset, heating or cooling output, and differential. Up to nine staging modules can be add to the A350 for complete versatility.


  • multiple staging of boilers or chillers
  • staging of refrigeration compressors
  • multiple fan staging for cooling tower

Johnson Controls Modular Electronic Sequencer (Click to enlarge)

The System 350R353/S353 Modular Electronic Sequencer is designed to provide multistage control in HVAC/R applications. The R353 Signal Input Module accepts input signals of 0 to 10Vdc, 0 to 20mA, or 135 to 10K ohm slidewire.


  • Electronic accuracy and repeatability
  • Field selectable direct-, reverse-acting, or mixing applications
  • Field selectable time delay
  • Connect up to ten S353 stage modules
  • Wall or DIN rail mounting
  • Plug-in connection


  • Electronic forced air systems
  • Electric boiler heating element staging
  • Boiler staging
  • Refrigeration and air conditioning capacity control
  • Multi-stage combination heating/cooling systems
  • Heat pump
  • Multi-stage fan systems for farm and industry
  • Heat recovery systems

Johnson Controls 24 Volt Power Module

The Y350R Power Module is a rectified AC power supply module designed specifically for use with the System 350 Modular Controls System. It provides a convenient method of powering the System 350 modules if 24Vac power is not available.

Johnson Controls Temperature Sensors and Accessories

Part # Sensor Accessories  
ADP11A-600R 1/2" EMT conduit adapter (box of 10) Call... Add to Order
SHL10A-600R Sun shield, single sensor Call... Add to Order