Using the same example as on another webpage in looking at humidity:
- Air Mass A: Air with 45% relative humidity at a temperature of 95 degrees F.
- Air Mass B: Air with 90% relative humidity at a temperature of 70 degrees F.
- Air Mass A has a dew point of 70 degrees.
- Air Mass B has a dew point of 67 degrees.
Based on this comparison, if Air Mass B was in the crawl space and Air Mass A was outside, then the system would wait to ventilate with fans until conditions improve.
Now, when the temperature and relative humidity outside change in Air Mass A, the calculations will change.
- Air Mass A: Air with 90% relative humidity at a temperature of 60 degrees F.
- Air Mass B: Air with 90% relative humidity at a temperature of 70 degrees F.
- Air Mass A now has a dew point of 57 degrees.
- Air Mass B has a dew point of 67 degrees.
Even though Air Mass A has a much higher relative humidity of 90%, the air temperature has dropped to 60 degrees F. The new dew point of Air Mass A is now 57 degrees and lower than Air Mass B. This would allow the ATMOX System to use outside air to dry.
For proper ventilation for moisture control, it takes the ability to compare the air masses to make sure that the outside air being brought in is actually drier. Moisture control requires the proper measurement tool, in this case dew point.