Equipment Information Page
Below Find Information On:
How Many Pieces Of Equipment You Need For Water Damage Situation
Below Find Information On:
How Many Pieces Of Equipment You Need For Water Damage Situation
This explanation comes from IICRC S500-2006 Guidelines For Water Damage Restoration Page 231.
"Controlling Airflow to Accelerate Evaporation "
"The increased rate of evaporation caused by airmoving devices is directly related to the airspeed
across the wet surface. Airmoving devices used to create a general drying environment, when practical,
should be set up so that continuous rapid airflow is provided across wet surfaces. In many structural
drying situations, one of the most difficult areas to dry is the lower part of the wall where it meets the
floor. One efficient way to create rapid airflow at this point is to install airmovers in a circular airflow
pattern, insofar as is possible. To do this, restorers should install one airmover for each 10 to 16 linear
feet of wall, with the outlet of each airmover pointing in the same direction. With the airmover almost touching the wall, restorers should aim its outlet at the wall at a 15-45 degree angle, depending upon the air-moving device used (centrifugal, axial). In addition, restorers should consider installing at least one air-mover for each small bathroom, closet or other offset or inset. "
Initial Dehumidification Factors
Type of Dehumidifier* Class 1 Class 2 Class 3 Class 4
Conventional Refrigerant 100 40 30 N/A
Low Grain Refrigerant (LGR) 100 50 40 50
Desiccant 1 ACH 2 ACH 3 ACH 2 ACH
*This chart has recommended figures used to determine initial dehumidifier requirements. They may change based on
psychrometric readings and types of materials present. Technician discretion is advised.
Initial Conventional Refrigerant and Low Grain Refrigerant Dehumidifier Calculations
Formula: ft3 of space ÷ divisor from Table = initial ppd required for effective drying.
Example: 1500 sf Class 2 water project @ 12,000 ft3 ÷ 50 pints (LGR) = 240 ppd at AHAM.
If the LGR dehumidifier’s AHAM-rated capacity is 120 ppd, then 2 will be needed initially.
Initial Desiccant Dehumidifier Calculations (based on air exchanges per hour or ACH)
Formula: ft3 ÷ 60 min = cfm x # ACH (see chart) = total cfm required. Divide this number by the
dehumidifier’s process cfm = # units
1. Example: 3000 sf Class 4 project with 12' ceilings = 36,000 ft3
2. 36,000 ft3 ÷ 60 minutes = 600 cubic feet per minute (cfm)
3. 600 cfm x 2 ACH = a requirement for 1200 cfm of desiccant dehumidification
4. 1200 cfm ÷ desiccant dehumidifier output (e.g., desiccant dehumidifier @ 600 cfm) = 2 units
needed for effective drying
Note: The recommendations arrived at using this process form a starting point that is based on research
and observation in IICRC-approved Applied Structural Drying houses. Psychrometric readings recorded
on the Daily Humidity Record dictate decisions about on-going dehumidifier capacity throughout the
drying process. Adjustments may be necessary.
Please note that any information noted here comes from the IICRC S500-2006 edition and it is highly recommended that any decisions made on equipment uses, one must read and understand completely the complete IICRC S500-2006 or up to date edition before making any final decisions.
Type of Dehumidifier* Class 1 Class 2 Class 3 Class 4
Conventional Refrigerant 100 40 30 N/A
Low Grain Refrigerant (LGR) 100 50 40 50
Desiccant 1 ACH 2 ACH 3 ACH 2 ACH
*This chart has recommended figures used to determine initial dehumidifier requirements. They may change based on
psychrometric readings and types of materials present. Technician discretion is advised.
Initial Conventional Refrigerant and Low Grain Refrigerant Dehumidifier Calculations
Formula: ft3 of space ÷ divisor from Table = initial ppd required for effective drying.
Example: 1500 sf Class 2 water project @ 12,000 ft3 ÷ 50 pints (LGR) = 240 ppd at AHAM.
If the LGR dehumidifier’s AHAM-rated capacity is 120 ppd, then 2 will be needed initially.
Initial Desiccant Dehumidifier Calculations (based on air exchanges per hour or ACH)
Formula: ft3 ÷ 60 min = cfm x # ACH (see chart) = total cfm required. Divide this number by the
dehumidifier’s process cfm = # units
1. Example: 3000 sf Class 4 project with 12' ceilings = 36,000 ft3
2. 36,000 ft3 ÷ 60 minutes = 600 cubic feet per minute (cfm)
3. 600 cfm x 2 ACH = a requirement for 1200 cfm of desiccant dehumidification
4. 1200 cfm ÷ desiccant dehumidifier output (e.g., desiccant dehumidifier @ 600 cfm) = 2 units
needed for effective drying
Note: The recommendations arrived at using this process form a starting point that is based on research
and observation in IICRC-approved Applied Structural Drying houses. Psychrometric readings recorded
on the Daily Humidity Record dictate decisions about on-going dehumidifier capacity throughout the
drying process. Adjustments may be necessary.
Please note that any information noted here comes from the IICRC S500-2006 edition and it is highly recommended that any decisions made on equipment uses, one must read and understand completely the complete IICRC S500-2006 or up to date edition before making any final decisions.
For a complete view of the IICRC S500-2006 edition please click here