Question

• How is Grain Depression calculated within Mitigate / MICA?
• Grain Depression isn't displaying expected calculations
• Why is a GD (grain depression) reading negative?

Answer

Grain Depression = refers to the difference in the grains per pound (GPP) of water vapor between two air masses. It’s commonly used in the HVAC and dehumidification monitoring to measure how effectively these systems are drying or adding moisture to the air.

Grain Depression in HVAC and Dehumidification

• For HVAC systems, Grain Depression is the difference between the GPP of the Affected Air (inside air) and the GPP of the air exiting the HVAC system.
• For dehumidifiers (DEHU), it compares the GPP of the Affected Air to the air leaving the dehumidifier.

Calculations

Mitigate/MICA uses standard methods to calculate this value. Grain Depression is calculated by subtracting the GPP of the system (HVAC or DEHU) from the GPP of the Affected Air:

• Grain Depression = Affected Air GPP - HVAC/DEHU GPP

For example:

Affected Air GPP reading: 46

HVAC GPP reading: 115

Grain Depression = 46 - 115 = -69

A negative value in Grain Depression (like the example above) indicates that the HVAC system is adding moisture to the air, rather than removing it.

In dehumidification, a positive Grain Depression is desirable, as it shows that moisture is being effectively removed from the air. Conversely, a negative or very low Grain Depression suggests that the system is not working efficiently and may be introducing moisture into the space instead of drying it.

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