Logo Neptronic

SKS4 - Steam to Steam Humidifier

  • Capacities from 17-1250lb/hr (8-570kg/hr) of steam
  • Boiler steam pressure from 5 to 15 psi (34.5 to 103 kPa)
  • Stainless steel 316 heat exchanger
  • Comprehensive scale management system cleans within minutes
Steam Distribution
  • In-duct distribution systems
  • Multi-Steam SD/HD and S.A.M. systems available
  • Custom-made to fit duct or AHU
Outdoor Unit
  • Fully insulated
  • Easy installation
  • Anti-freeze and overheat protection
Designed specifically for the SK4 series
  • One controller
  • One menu across humidifier types
  • Provides consistency and ease of use
Sensors and Controls
  • Higher energy conservation
  • Lower costs and higher values
  • Seamless integration and interoperability
  • Overview

  • Steam Distribution

  • Outdoor Unit

  • Integrated,
    Multi-Platform Controller

  • Humidity Sensors and Controls

SKS4 - Overview

The SKS4 humidifier provides chemical free steam by using an on-site central boiler or steam generating station as a heat source. The raw steam under pressure from the boiler provides the energy to produce clean, sterilized steam through a heat exchanger.

  • Environmentally-friendlyEnvironmentally friendly
  • AFECOptimize the use of boiling water – no unnecessary drain!
  • Ease-of-maintenanceEase of maintenance with comprehensive scale management system
SKE4 OVerview Brands

Advantages of Steam to Steam Humidifiers

  • Capacities from 17 to 1250lbs/hr (8 to 570kg/hr) of steam
  • Stainless steel (for raw steam) heat exchangers
  • Ease of servicing: clean and re-install within minutes
  • Patent-pending water level detection system using 2 sensor technologies
  • Comprehensive scale management system
  • Uses either domestic, RO or DI water
  • For Multi-Steam and SAM in-duct distribution systems
  • Available with BACnet MS/TP or Modbus communication
  • Optional ethernet module for BACnet IP or Modbus IP, and web services
  • Patented Anti-Foaming Energy Conservation (AFEC) System
  • Drain water tempered to below 140°F (60°C)
  • Now available with an OSHPD option – the SKS4 meets the requirements of OSHPD Special Seismic Certification Preapproval (OSP)
  • Supplied with Neptronic actuated globe valve, giving full modulation control of low pressure steam

Linear Actuated Globe Valve

The Neptronic electric linear actuated globe valve provides a modulating output for close humidity control. Each unit comprises a linear actuator that is directly coupled to the valve. The SKS4 sends an analog control signal to the actuator to open and close in proportion to the demand of steam.

  • Electronic feedback from the actuator allows the SKS4 controller to monitor the exact position of the valve
  • Failsafe feature closes the valve when there is a power failure
  • Delivers a maximum of 100 pounds (450 Newtons) force at rated voltage
  • Sizing ranges from 1/2 inch to 2 inches (15mm to 50mm).

For low pressure steam applications, it is necessary to shield the actuator from heat generated by the valve. This is accomplished by a factory installed adapter kit, the DDSTM.

System Overview

SKE4 parts chart

In-Duct Distribution

For Multi-SteamTM SD/HD and S.A.M. in-duct distribution systems.

  • Efficient and economical, S.A.M. and S.A.M. E2 systems are suitable for installations where absorption distances are short (less than 5ft/1500mm) and/or low/restricted duct temperatures are in effect
  • Custom-made to the dimensions of the duct or AHU, the Multi‑Steam™ SD/HD systems are used at critical locations within the air handling systems where absorption distances are extremely short (less than 3ft/900mm) or where low air duct temperatures are present
  • For more information on our Steam Distrbution Systems, please click here




Operation in all climates

  • Hinged doors provide full access (serviceability) from the front, back and top of unit
  • Fully insulated and constructed from heavy duty steel
  • Stainless steel bottom drip pan
  • Zinc primer and polyurethane powder coating for resistance against scratches and corrosion
  • Built-in anti-freeze and overheat protection
  • Easy installation on a roof curb, stand or slab

The SK Controller is configured specifically for your SKE4, SKG4 or SKS4 Humidifier.

  • User-friendly interface consisting of a menu driven 128 x 64 LCD with 8 function buttons for faster configuration and operation
  • User rights management allows for menu to display only functions available to the category of user logged in
  • Quick Config menu allows for faster and easier installation, by displaying only the most commonly used functions and configurations
  • Independent scheduling system for unit operation and drain cycle, configurable via the menu or the BACnet communication interface
  • In-field firmware upgradeable via SD card, USB or BACnet
  • Simple viewing and exporting of trending log and alarm log
controller 2

Optional Features

  • The selectable BACnet MS/TP or Modbus communication interface allows access to over 75 objects/registers for integration with a BMS and IoT(Internet of Things)
  • Ethernet Module
    • Bacnet IP or Modbus IP
    • Web services make it possible to perform humidifier configurations, remote diagnostics and many more functions from any location
controller 2

An updated and highly accurate line of sensors and controls was developed and produced by Neptronic specifically for the new SK4 series.


  • Used to program the SK humidifiers
  • Icon-driven information and 1 line of text information
  • 4 wires between humidistat and SK
  • Programmable PID on humidity


  • BACnet MS/TP (model HROB20 only)
  • 4 analog and 2 dry contact outputs
  • 2 external sensor inputs
  • Alarm and low signal selector input
  • Independently configure PID on humidify & dehumidify ramps
  • Adjustable setpoint with auto reset from external sensor


  • Built-in temperature sensor
  • Plastic cover for wall mount installation
  • 2 analog outputs (0-10 Vdc)
  • High accuracy and stability


  • Built-in temperature and humidity sensor
  • 2 analog outputs (0-10 Vdc)
  • Status LED


  • Built-in temperature and humidity sensor
  • On/Off high limit humidistat with on-board setpoint adjustment
  • 2 analog outputs (0-10 Vdc)
  • Status and high limit LEDs
  • 1 dry contact output