NexSys Dual System Controller for Boiler and Cooling Tower Water Treatment

Boiler and cooling tower control system that seamlessly integrates with Building Management Systems.
NexSys Controller Image

A NexSys dual system controller provides the flexibility to meet each site’s specific needs. It is designed for both boiler and cooling tower water treatment, offering greater efficiency. 

The NexSys boiler and cooling tower controller can easily communicate with Building Management Systems right away. It can be integrated into their total systems. This allows a water treater to become an asset to your customer.

From high schools to large commercial buildings, facility engineers use Building Management Systems to collect data from thousands of points throughout their site.  Easily become part of their network by ordering a NexSys controller today! 

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NexSys Boiler and Cooling Tower Water Treatment Controller Overview

  • Each unit can control up to 2 cooling towers or up to 4 boilers simultaneously – lowering your capital cost for the entire site.
  • Building Management System connectivity.
  • You determine the inputs you need for your system, including: Conductivity, pH, ORP, Water Meters, Flow Switches, Trace Chemistry, and any 4-20 mA input.
  • Six output relays are standard, and every NexSys may be expanded to ten output relays total.
  • Sensor inputs connect to Smart Nodes – small circuit boards in a compact design. 
  • The nodes become an internal NexSys network that expands as you need it.
  • The nodes can be located as much as 400 meters / 1300 feet from the NexSys controller– giving you flexibility and leveraging the power of this datalog water treatment controller.

NexSys Boiler and Cooling Tower Controller Updates

  • In late 2020, Lakewood updated the graphical interface for the NexSys systems, giving a more modern appearance, and clarity to the user experience.
  • We have also made some simplifications in the BACnet/IP interface, eliminating the need for external components for Building Management System integration.

Standard Features

  • Color touch screen.
  • Datalogging.
  • Onboard graphs.
  • Six output relays expandable to ten output relays for user configurable operations such as:
    • Feed by percent of blowdown time
    • Feed by setpoint with percent of time feature as part of spaced feed
    • Trace chemistry control
    • By makeup totalized gallons
    • By blowdown totalized gallons
    • By percent on-time
    • By scheduled feed by day and time
  • Up to eight active 4-20mA input readings
    • 2 tower conductivity inputs
    • 2 makeup conductivity inputs
    • pH and ORP inputs
  • Two flow switch inputs configurable to any relay output
  • Two water meter inputs with field expansion capability to four

Additional Features

  • LonWorks, MODbus, and BACnet communications interface
  • Ethernet capability through an HTML interface
  • The capability to send E-service reports to a subscribed service
  • The ability to display operating values with time and date stamps on color coded graphs with zoom and scroll features
  • Trace chemistry capable
  • Enclosure is NEMA 4X rated
  • Ability to add four digital inputs
  • Ability to mount every sensor/input up to 400 meters away from the controller via 4-wire twisted pair
  • Ability to provide complete water quality control for two cooling towers or up to four (4) boilers at the same time
  • On-board help screens with wiring, programming and maintenance instructions
  • Left or right exit plumbing assemblies available

Product Documentation

Cooling Tower Controller Application

Boiler Water Treatment Controller Application


  • Type: NexSys Dual Control System
  • Conductivity Sensor: Optional conductivity sensor
  • pH Sensor: Optional pH sensor
  • ORP Sensor: Optional ORP sensor
  • Make-up Conductivity: Optional make-up conductivity sensor
  • Output Relays: Optional relays
  • Flow Switch: Optional flow switch
  • Water Meter: Optional water meter
  • Analog Input: Optional 4-20 mA input
  • Output Signal: Optional 4-20 mA output signal
  • Remote Display: No remote display
  • Mounting plate: Optional mounting plate
  • Conductivity Range: 0 – 5,000 μS
  • Maximum Pressure: 140 psi (9.65 bar) @ 100 °F
  • Process Temperature: Max 140°F (60°C)
  • Ambient Temperature: -4° to 158°F (-20° to 70°C)
  • Conductivity Resolution: 10 μS
  • Conductivity Accuracy: ± 40 μS
  • pH Range: 2-12 pH
  • pH Accuracy: ± 0.05 pH
  • pH Resolution: 0.01 pH
  • ORP Range: -1000 to +1000 mV
  • ORP Accuracy: ± 5.0 mV
  • ORP Resolution: 1 mV
  • Accuracy & Repeatability: ± 1.0% of scale
  • Deadband/Setpoint: User programmable
  • Enclosure: NEMA 4X, ETL
  • Timer: Relay run time exceeded
  • Power: 120/240 VAC 50/60 Hz
  • Relay Ratings: 120VAC 3A each, 15A total

Have questions? Get in touch with us!


Customer Testimonial:

“Morning Joel, Ed,

I wanted to thank you both for assisting Sean Stanwood in the installation and programming of the NexSys modem yesterday. 

With a quick phone call, Sean was able to connect the modem to the NexSys controller and demonstrate to our customer how the system can be monitored and controlled remotely. 

Our customer was thrilled by the ease of which we did the install and demonstration of the modem’s abilities. Very impressed!!

We also were confronted with an error code on the water meter recorder and totalizer. We showed them how to use the reset button in the back of the panel and the system corrected itself and started working perfectly, counting feed water flow and total gallons passing the paddle wheel meter. 

Again, we thank you for your support of our field representative, as it helps our professional image.”

– Bill Stanwood, Owner, NW Water Technology.

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