The climate control is of primary importance in the mushroom growing. There are several parameters which affect and need to be kept in very narrow range during different stages of the production process in order to guarantee the quality of the mushrooms.

CO2 as most important parameter

One of the most important parameters, which needs strict control, is the CO2 concentration in the air. It is measured in ppm and is the major factor for obtaining good quantity, quality, and size of the produced mushrooms. The values of this parameter vary for different kind of mushrooms.
Normally, during spawn run, the level of CO2 concentration may reach very high levels – it may surpass the number of 10 000 ppm. While these CO2 values are acceptable at this phase, they must be seriously decreased during next stages of growing.

CO2 concentrations for champignon mushroom

For white mushrooms for instance, during pin heading and fruit body development, the values of the CO2 concentration may vary somewhere in between 1200-1500 ppm. When the pin reaches 1 cm in height, its cap and stem must be equal in diameter. If the cap is smaller than the stem, then this is an indication that the aeration is not enough and CO2 concentration is above the norms. On the other hand, if the cap is bigger than the stem, this means that the quantity of fresh air in the room is more than the necessary volumes.

The solutions with TCW220, TCW181B-CM and TSG200

In order to maintain the parameters within certain limits, different combinations of hardware and software can be used. Each of them has its pros and cons. This article will discuss a system installed and functioning in a specific project.
The system consists of two controllers – TCW181B-CM и TCW220, a CO2 sensor – TSG200 and software for control working under WIN OS. The system may control the CO2 levels in two different growing rooms.
In order to secure the safety and the smooth operation of the sensor, it is mounted in an appropriate place outside of the growing rooms. One sensor operates for two growing rooms. The controlled air is brought into the sensor through a system consisting of plastic tubes, valves, and a compressor.
The TCW220 controller manages both pneumatic valves. The CO2 sensor is attached to the controller. The controller itself is run by a software through SNMP protocol and periodically opens and closes the corresponding pneumatic valves through its relay outputs. Thus the controller brings in air from different growing rooms to the sensor and at the same time provides data on the measured concentration of CO2.
TSG 200 is a precise sensor for carbon dioxide measuring. The device itself uses a built-in non-dispersive infrared element (NDIR), which is responsible for the monitoring of the CO2 concentrations. The communication with the controller is carried out by a 1-Wire interface.
The software sends instructions and commands to the mechanisms for ventilation, after analyzing the data on the CO2 concentration in the rooms and taking into account the rest of the parameters which affects mushroom growth. The communication is carried out through SNMP protocol with the help of the relay outputs of the TCW181B-CM controller.
A block-scheme of the system regulating the CO2 concentration in the growing rooms can be seen below: