There are typically 12 different answers from the 12 "teams."

The bottom line is that Restoration Companies have absolutely no clue how their equipment operates, or how their equipment will perform on the job.

For our house, affectionately named, "Chuck's House," it calls for 2 Phoenix 200's on the first day, then 1 for the second and third day.

The last class said it would take up to 5 Phoenix 300's and up to 7 Standard 120's!

There is NO WAY in the world that they could ever dry our building. Too much dehumidification is detrimental to the job, mainly because the heat generated by the excessive DH's only heat up the environment until they can no longer pull water.

(*Remember: Refrigerant DH's ONLY work in the temperature range of 70 to 90 degrees.)

That is leaving the carpet and pad in the structure to dry.

It gets WORSE when we ask them how much dehumidification they would put on the job if we were to remove the wet carpet and pad from the structure before drying.

9 times out of 10 they say they would leave it the same...

Why does this matter?

Because 90% of the water left in a structure after extraction is located in the carpet and pad.

By removing the bulk of the water needed for dehumidification, you also remove the need for as many dehumidifiers.

So, What's The Answer?

There Are 2 Formulas For Figuring DH Requirements:

1) REFRIGERANT DEHUMIDIFIERS

2) DESICCANT DEHUMIDIFIERS

Refrigerant Dehumidifiers actually convert the water vapor into

a liquid, therefore, these types of dehumidifiers are rated by

manufacturers in PINTS.

Desiccants do not convert the vapor to a liquid and, therefore, manufacturers rate this type of dehumidifier by CFM of airflow. The following formulas will help you learn to calculate PINTS of dehumidification necessary for Refrigerant Dehumidifiers, and CFM of airflow necessary for Desiccant Dehumidifiers.

1) Refrigerant Dehumidifiers:
HOW TO DETERMINE REFRIGERANT DEHUMIDIFICATION
There Are Four (4) Pieces Of Information Necessary For Determining Refrigerant Dehumidification Requirements:

1) The Cubic Feet Of Airspace In The Affected Area To Be Dried
2) The Classification Of Water Damage (Class 1,2,3 or 4)
3) The Division Factor
4) The Number Of Pints That Your Dehumidifier Will Pull At AHAM.

Here's How It Works:

1) The first step is to calculate the total airspace that is to be dried. This is obtained by multiplying: Length X Width X Height

2) Once the Cubic Feet has been calculated, the next step is to determine the Class of water damage you are dealing with. (AFTER EXTRACTION)

The Classification of Water Damage is Determined By How Much Water Remains In The Structure After Extracting/Physically Removing All Possible.

There are 4 different classifications of water damages:

Class 1 - Minimum amount of water in structural components. Small Area Of Carpet And Pad Wet, Not The Whole Area. Often will have hard surface flooring. Water has wicked up walls less than 24 inches.

Class 2 - Substantial amounts of water left in structural components. Will Have Wet Carpet and Pad Covering Majority of Area. Water wicked up walls less than 24 inches. Crawlspaces with dirt flooring also come under this class.

Class 3 - Maximum amount of water left in structural components. Entire Area Has Wet Carpet And Pad. Water might have come from overhead. Walls and ceilings are wet.

Class 4 - Specialty Drying Situations. (Similar in Amount of Water to a Class 1) Very little water in structural components, however, the materials being dried release water slowly. (I.E. Hardwoods, Plaster, Brick, Concrete, Stone, Sub-Flooring) Requires VERY LOW GPP's (Specific Humidity.) Cannot Use Standard/Conventional Dehumidifiers.

TIP: Most Jobs Will Be Either A Class 1 Or A Class 2!

3) Find The Division Factor For The Appropriate Class & Dehumidifier On The "Determining Dehumidification" Chart And Divide The Cubic Feet By The Factor.

THIS WILL GIVE YOU THE NUMBER OF PINTS OF DEHUMIDIFICATION THAT IS NECESSARY FOR YOUR JOB.

Each class has a different division factor based on the type of DH that will be used on the job.

EXAMPLE: For a Standard DH in a Class 2, the division factor will be different than an LGR's.

Refer to the "Determining Dehumidification" Chart found HERE.

4) Find The Number Of Pints Of Water Your Dehumidifier Will Pull At AHAM On The Chart, Then Divide Your Pints Required By That Number.

THIS WILL GIVE YOU THE NUMBER OF DEHUMIDIFIERS NECESSARY FOR YOUR JOB.

TIP: ALWAYS ROUND UP!

WHEN THE NUMBER CALLED FOR IS A PERCENTAGE OF THE NEXT NUMBER UP, (IE: 2.34) ALWAYS ROUND UP TO THE NEXT PIECE OF EQUIPMENT (2.34 = 3)

2) Desiccant Dehumidifiers
How To Determine Desiccant Dehumidification
Calculating Desiccant dehumidification is the same in formula to the refrigerant equation.
The Desiccant formula, however, will be figuring the number of CFM of airflow you will need from your DH instead of PINTS necessary.

The equation is based upon the number of times per hour that the total cubic feet of air in the affected area must be "exchanged" (pass through the machine) per hour.

This term is referred to as an "ACH" = Air Exchange per Hour

For 1 ACH, You divide by 60

To achieve one air exchange per hour, you divide the cubic feet of airspace by the number of minutes in an hour (60).

(In other words, the total cubic feet of air must pass through that machine once in 60 minutes.)

For 2 ACH, you divide by 30.

(The air must be "exchanged" ((pass through the machine)) every 30 minutes)

For 3 ACH, you divide by 20.
(Air exchanged every 20 minutes.)

It is still a four-step process:
1) Calculate The Cubic Feet Of Airspace To Be Dried
Length X Width X Height

2) Determine The Class of Water Damage
(See #2 Above on Classes)

3)Find The Division Factor (ACH)

(See Chart Found HERE)
Class 1 - Divide By 1 ACH (60)
Class 2 - Divide By 2 ACH (30)
Class 3 - Divide By 3 ACH (20)
Class 4 - Divide By 1 ACH (60)

Divide the Cubic Feet of Airspace to be dried by the Division Factor.

This gives you the TOTAL # CFM OF DEHUMIDIFICATION NECESSARY.

4) Find The Desiccant DH You Will Be Using On Your Job.

Divide the CFM of Dehumidification Required by The Amount of Air The Desiccant You Will Be Using Will PROCESS (Blow Out, Not Take In).

This Gives You the Number Of These Machines You Will Need To Dry This Job.

TIP: Always Round Up!