AHAM Rating of Dehumidifiers


The Association of Home Appliance Manufacturers, oversees many things. One of those things is testing the “output” of condensed liquid from refrigerant dehumidifiers. They  remove moisture from the air by changing vapor to liquid (condensation)

When you buy a refrigerant dehumidifier, the paperwork gives the AHAM rating. This is the amount of water that comes out of the unit in 24 hours of operation.

This output of a dehumidifier is figured by putting the dehumidifier into a chamber, at a temperature of 80 degrees, 60% relative humidity, for 24 hours. The condensation generated, is collected and measured. This becomes the AHAM output of that dehumidifier.

The best reason for doing this is to have a consistent measurement of dehumidifier output that lets us compare one unit to another. When you shop for a dehumidifier, you can compare, not only, the cost of the unit, but, also, the pints of vapor removed, daily.

Having AHAM do the same test, on two different dehumidifiers and get 80 pints/24 hrs, on one unit and 120 pints/24 hrs, on another unit gives you, trustworthy, results.

CAUTION: Sometimes, you will see, “Manufacturers ratings”, listed. This can be a test done in 90 degrees and 70% RH rather than the 80 degrees and 60% RH. With these higher test numbers, the “pints/day” will be higher. Be sure you are comparing AHAM “pints/day” when checking capacity of a dehumidifier.

It’s a simple calculation to figure the cost of each pint the unit removes. Divide the cost of the unit by the pints/day and see how many pints you are getting for each dollar spent. Obviously, there are other things that affect the cost of a unit, which you would, also, consider.


Knowing the capacity of the unit allows the restorer to install the correct number of units to get the job done. There’s a simple formula to figure the number of pints per day, evaporating into a room with wet material.

Let’s use our imagination and say there are 100 pints/day evaporating into a room. We need to, now, remove 100 pints/day. If we know the rating of our dehumidifier is 50 pints/day…….we need to have 2 units running to remove the 100 pints going into this room.


Some Insurance Companies have adopted a policy of paying for a smaller capacity dehumidifier than the “last one” the restorer installed,  because it was more capacity than was needed to remove the vapor in the area. It can be a good idea to purchase some lower capacity units to be able to put a lower capacity unit in rather than getting underpaid for a larger one.


To keep the output of the unit working as good as new, it’s a good idea to clean the coils of the dehumidifier, every so often, depending on the dust conditions on the job. Insulation on the coils is not a good thing! :) Coil cleaner can, often, take care of this.



                     MAKE MONEY!


                     Dennis Klager

                     IICRC Instructor



Copyright 2012 by Dennis Klager