Determining Drying Equipment Requirements

Air Movers

High velocity air movers placed at a 45º angle against the wall every 12-16 linear feet with one air mover placed in the middle of the room facing down at the floor. It is important to use low amperage drying equipment. The wetter the structure materials, the closer you set the air movers.

Dehumidifiers

(use the charts below)

Formula: Cubic feet of affected area ÷ Division factor by Class of Water Loss = # of pints at AHAM * to be pulled in 24 hours.

1. First, the Class of Water Loss must be assessed. Class is not to be confused with the Type of Water Loss. ( More Info ).
2. Calculate the cubic footage of the area to be dried.
• EXAMPLE: Room size of 30' x 50' = 1500 SF x 8' ceilings = 12,000 c.f.
3. Determine how many pints must be pulled per day given Class of Water Loss and type of dehumidifier(s) being used. The chart below shows the correct dividing factor to determine the pints per day that must be removed from the air depending upon the Class of Water Loss and type of dehumidifiers being used. Dividing the total cubic feet of air in the structure by the dividing factor tells us how many pints per day need to be pulled from the structure to achieve an effective drying goal.
• EXAMPLE: Assume this example is a Class 2 water loss and the restorer is using refrigerant dehumidifiers. Divide: 12,000 cf ÷ 50 pints (LGR) = 240 pints at AHAM. This means the dehumidifier must be capable of removing 240 pints of moisture per day.
4. Use the chart below showing the AHAM capacity of various dehumidifiers to determine and justify the exact number of dehumidifiers that are necessary to do the job. After the first or second day, we're dependent on the specific humidity (gpp) produced by a particular dehumidifier to continue effective drying. After the first day, we can determine the adequacy of our drying set-up using psychrometric measurements.
   • EXAMPLE: We know from the previous calculation that 240 pints must be pulled per day. If we are using a LGR that pulls 124 pints AHAM, we will need at least two dehumidifiers on the job. Further, if we only have conventional refrigerants and we divided 12,000cf by 40 for 300 pints per day and were using 64 pint conventional refrigerants, we need at least five units to do the same job.

Phoenix 200HT 140 pints 325 cfm @ 7.5 amps

Phoenix 250HT 150 pints 325 cfm @9.1 amps

* Manufacturer published specifications

* Association of Home Appliance Manufacturers