Crawl space dehumidifier

This tool is necessary in every house that has problems with mold and mildew. There are some characteristics that should be taken into account for choosing a crawl space dehumidifier and you can find some of them below.

Humidity level and air changes

These two elements should be determined for the room where the crawl space dehumidifier will be placed.

You can either use a hygrometer which is not expensive at all or use a “rule of thumb” test. You can obtain the following results:

  •  Moderately Damp – If it smells musty and feels damp in humid weather, the air needs 3 changes per hour.
  •  Very damp – The musty and damp area can be felt on any type of weather; the air needs 4 changes per hour.
  •  Wet – Mold and mildew can be seen; the air needs 5 changes per hour.
  • Extremely wet – You can see water; the air needs 6 changes per hour.

Crawl space volume

After finding out the first 2 requirements, the necessary cubic feet will be next for the dehumidifier. This can be found out easily by multiplying the length, the height and the width.

Air flow

The crawl space dehumidifier will need to be able to create the proper CFM (cubic feet per minute) for the entire space, without running all the time. The CFM can be determined by multiplying the cubic feet with the space times the air changes and the result divided by 60. For example, a space that has 3000 cubic feet and needs 3 air changes per hour will need 150 cubic feet per minute air flow.


Besides the fact that the dehumidifier will create air flow, it also needs to take the moisture out of the air. This measurement can be done by founding the number of pints of water per day that will need to be extracted from the area. It can range from 10 pints of water for 500 square foot space to 51 pints of water for a 3000 square foot space. The pints of water can vary from house to house because you have to take into account the area’s climate, the location and the habits of every family.


After having the measurements for the CFM, cubic feet per minute of air moved and the pints of moisture, you can finally choose the crawl space dehumidifier that has all these capabilities. Also, make sure that the unit will not be too big, it will have energy and the temperature will not create problems.

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