Factors Affecting Greenhouse Humidification

Most greenhouse applications require artificial humidification to maintain moisture levels that provide an ideal growing environment. High-pressure misting systems are a practical and effective option for controlling greenhouse humidity levels. 

Before considering the type of humidification system or system design, a good understanding of the environment is required. The factors to consider include the size of the structure, the humidity level required, the amount of air exchange, the seasonal ambient temperature and relative humidity, and the racking structure within the greenhouse.

Once the important factors have been accounted for, an appropriate mist system design can be created. In some cases, the design will include mist lines mounted overhead. In other cases, it will include a fan that incorporates an air stream into the mist to achieve a higher evaporation rate and better distribution of humidity.

Consider these factors when choosing a greenhouse humidification system:

• If the greenhouse is empty, the volume of air to be humidified increases dramatically. Do not expect the same results from a system in a full greenhouse as compared to a system in an empty greenhouse.

• If there is too much air exchange, humidity levels will not increase beyond a certain point. That maximum achievable humidity level is directly related to the introduction of fresh air and the output capacity of the system.

• Restricting air exchange (or increasing mist system output) affects how quickly the required humidity level is achieved, and how often the system will cycle. Over a certain period of time (as long as fresh air is not constantly introduced), the mist system can provide humidity levels in excess of 90%. If the time it takes to accomplish the needed humidity level is too long for a specific application, the system flow should be increased.

Tips for Choosing the Correct Humidification System

In the past, controlling humidity was a challenge because hygrometers did not have a control system that required constant monitoring and manual adjustments to increase or decrease humidity. Hygrometers also tended to be inaccurate — at least until technology advances led to amazingly accurate sensors and controllers.

Today, automated microprocessor can both complete the measurement of moisture content in the air and automatically signal the system to adjust. This works exactly like the relay of electronic information and signals between a thermostat and a heater or air conditioner.

With modern, high-quality humidity controllers in place, your system can be set and maintained for humidity levels in a specific zone. These systems also have external sensors that can be wired into the system, allowing the controller and the sensor to be in different locations and still communicate.

The system itself has two output relays and comes complete with a fully programmable delay start and stop. This allows the system to be set for your specific needs with the option to reconfigure the system as required as often as needed.

There are two different options for humidity sensors: low and high humidity sensors. In environments where the humidity will be maintained at a level of 10 to 70%, low humidity sensors will provide control for the vast majority of environments. 

There is also the option of high-humidity sensors. Using standard sensors in high-humidity environments will damage the microchip. The high-humidity sensor is recommended where the humidity levels exceed 70%. These units are designed with specialized filters to protect the microchip, even in very high humidity environments.

High-humidification systems can be used in greenhouses or other types of applications where humidity levels may reach as high as 97%. These sensors, even at this humidity, will be accurate to plus or minus 2%, which is considered one of the most accurate available today.

As with all of our products, Fogco humidity controller units are fully compatible with all of our fan systems. We also sell a full line of accessories for our sensors, controllers, and systems, including shielded cable, pin connectors, and conductor cables, providing everything you need to complete installation.

Contact Fogco online or call us at 800-607-6478 if you have questions. We would be happy to help design a system for you.