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SKG4 - Gas Fired Humidifier

  • Capacities from 110-810lb/hr of steam
  • Fully Modulating, ranging from 10lb/hr to maximum
  • One of the highest combustion efficencies in the industry
  • Automatic scale removal process (patented) for its heat exchanger
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

SKG4 - Overview

The SKG4 gas fired humidifier generates mineral free, odorless, sterile steam by using the power of natural gas or propane. Cost of operation and its carbon footprint is much lower than electric humidifiers with equivalent control accuracy.

  • Environmentally-friendlySmallest carbon footprint in the industry
  • AFECOptimize the use of boiling water – no unnecessary drain!
  • Ease-of-maintenanceEase of maintenance – clean and re-install in minutes
  • Ease-of-maintenanceModular design – flexible solutions for indoor/outdoor applications
SKG4 OVerview Models
SKG4 OVerview Brands

Advantages of Gas fired Humidifiers

  • Capacities from 110 to 810lbs/hr (50 to 370kg/hr)
  • Turn down ratio of 10:1 (minimum) up to 40:1 (maximum)
  • Functions with Tap, RO or DI water
  • Combustion efficiency: 83% to 87%
  • Easy servicing: clean and re-install within minutes
  • Smallest footprint in the industry
  • Patented Anti-Foaming Energy Conservation (AFEC) System
  • Advanced controller with multiple connectivity options
  • Waste water drained below 140°F (60°C)
  • Self-adjusting burner for altitude compensation

System Overview

SKG4 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

S.A.M. E2


Multi-Steam SD/HD

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
  • Connection can be made from side or through the roof curb
Outdoor Unit

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