Control of humidity through humidification and dehumidification systems

Humidity is the moisture content in the air.

Air at a given temperature can hold just so much moisture. Anything over 100% will give us condensation or rain.

Relative humidity is a percentage of that 100% capability.

Higher temperature air can hold more moisture. At lower temperatures this moisture is condensed out of the air.

As it’s being condensed out the relative humidity is at 100%. The point where condensation occurs is called the dewpoint temperature of the air.


70deg F and 70deg dewpoint gives us 100% Rh

As the temperature increases for this dewpoint the Relative humidity percent goes down because the air can hold more moisture. (Example 80 deg F @ 70 deg dp is less then the 100% RH at 71.6% RH)

When the temperature decreases the dewpoint starts going down with the temperature. The relative humidity stays at 100% and moisture is condensed out with the decrease in temperature.

When we remove that moisture say down to 55deg F and 55 deg dewpoint we’ve removed the moisture contained in the 70 deg dewpoint air down to 55 deg. It’s still at 100% RH but at 55 deg F.

Then if we reheat that air back to 70 deg F, we then have 70 deg F air at a 55 deg Dewpoint and a lower Relative Humidity 58.9% RH. Heating the air an additional 5 deg F to 75 degree F. would result in a 49.8% RH.

Removing moisture in the air by cooling then reheating it is called a DeHumidification & Reheat System

To get back to the 100% relative humidity at 70 deg F we would need to add moisture to raise that dewpoint from 55 deg to 70 deg which raises the relative humidity from 58.9% to 100% RH.

Adding humidity to the air is a Humidification System.

People and processes all rely on humidity control.

Offices look at Summer (Dehumidification) and Winter (Humidification) humidity control.

Process would look at controlling the space for their product. This could entail both humidification and dehumidificaiton or one of the above.

Each of the systems have different levels of equipment and controls depending on the relative humidity tolerances that we’re trying to be achieve.

Additional information to follow in the future.