Series EHU-700 Electronic Steam Humidifiers



Very sensible indeed. Internal software routines automatically monitor the operation of the EHU and display messages to indicate the condition. The unit will report on 10 different conditions.


Accurate, reliable humidity control is a sensible precaution to protect your investment in materials, equipment and personnel. Increasing the temperature of indoor air without adding moisture decreases its relative humidity (RH). And when RH falls to levels commonly found in heated indoor environments, moisture-retaining materials such as wood, paper, textile fibers and a wide range of food and chemicals begin to deteriorate.

Indoor air quality, proper control of moisture output, efficiency and ease of maintenance. Since steam scores high on all of these factors, a steam humidifier is clearly the best choice. And an Armstrong EHU may just be the smartest.


An Armstrong Series EHU converts ordinary tap water to steam and distributes it to bring the relative humidity up to the desired level. It is ideal for humidifying areas where no steam supply is available or where a steam source is too remote for easy or economical piping.

When the humidistat senses the need for humidity, a microprocessor converts the demand signal into an amperage requirement. Voltage is applied to the electrodes, and the fill valve begins to fill the tank. Water enters the bottom of the steam generator tank and rises until it reaches the electrodes. Upon contact, electrical current flows through the water, causing it to boil and produce steam. As the water level rises, increased current flows through the water, producing more steam. This increase continues until the required output (amperage requirement) is reached.

When the required output has been reached, the fill valve will cycle to maintain the required amperage. When the humidistat senses the additional moisture in the air, the demand for humidity begins to drop. As the demand falls, the output modulates down by decreasing amperage and, therefore, steam flow.

NOTE: This product is available with the Armstrong Temp-R-Drain, a device that mixes hot condensate and cold water to maintain a drain outlet temperature suitable for drainage directly to any plumbing system. Contact Armstrong factory representatives for more information.

Armstrong has been producing an EHU series for over 35 years with over six different series upgrades. We can truly say the 800 series is the smartest of them all. The brains of this unit is the 24VAC main PC board with an on board controller. The PC board is connected to the digital display and keypad, making the unit user friendly as well as making a plethora of information visible on the display. Taking it one step further, this unit also comes standard with native Modbus Controls, which creates a gateway for the information to be visible on your desktop. See below for some of the Features & Benefits that can be found in the EHU-800 series.

Digital Display w/ Keypad: Digital display that has the capability to see 50 different screens from current amp draw to when the unit will drain again, etc.

Self Diagnostics: The unit continuously monitors the operation through self diagnostics.If it sees an issue the unit first tries to fix it itself and then if the problem persist it will display one of eight messages to indicate the condition.

Adjustable Output: The EHU-800 series units are fully modulating, but the unit also has the ability to limit the maximum output. If anything in your system is to change such as the CFM, temp, ect, the output of the unit can be capped to accommodate each application.

Cleanable Tank: The tank provided with the EHU-800 series combines economical maintenance and convenience. You can easily disassemble and inspect the steam generator tank. The digital display will also alert when maintenance is needed. The onboard controller will analyze the amount of run time based on demand. When it is necessary, you have the option to clean the tank or replace it entirely.

Standard Communications: As mentioned above, all EHU-800 series unitscome standard with Modbus communications (RS485 connection). This allowsthe user to communicate with the humidifier through the Building ManagementSystem (BMS). The humidifier can be controlled and monitored from a remotelocation. Everything that is accessible through the front display of the humidifier,will be visible through the BMS. With being native Modbus, the unit can be easilyconverted to BACnet or Lonworks with the use of a protocol translator.

Onboard Controller: This series also features an onboard controller, which gives the user the capability to install sensors instead of a standard humidistator modulating high limit. This makes wiring easier as the sensors that are used to monitor the space conditions with the BMS can also be used to control the humidifier.

External connections: The water and drain connections are easily accessible points on the bottom of the unit to make installation much simpler and easier. This also eliminates some connection points inside the cabinet to help reduce the risk of electric failure due to moisture in the cabinet.

Smaller footprint: Over the years the EHU series has been the smallest of all the atmospheric steam generators. The width of the EHU-800 is slightly smaller than its predecessors, making it even easier to install.

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