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.
Step 1. First, the Class of
Water Loss must be assessed. Class is not to be
confused with the Type of Water Loss. (Category
1, 2, or 3).
Step 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.
Step 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.
Step 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.
| Dehumidifier * |
Pints/Liter at AHAM
* |
CFM/amps |
| Drizair 80-pint conventional refrigerant |
40 pints/18 liters |
150 cfm @ 8 amps |
| Ebac BD-80-XE conventional refrigerant |
40 pints/18 liters |
360 cfm @ 8 amps |
| Drizair 110-pint conventional refrigerant |
58 pints/29 liters |
150 cfm @ 5 amps |
| Drizair 1200 (120-pint) conventional refrigerant |
64 pints/31 liters |
227 cfm @ 6.4 amps |
| Evolution LGR (120-pint) conventional refrigerant |
70 pints/33 liters |
160 cfm @ 5 amps |
| Drizair 200-pint conventional refrigerant |
108 pints/51 liters |
450 cfm @ 12 amps |
| Ebac Orian 200-pint low grain
refrigerant (2 speed) |
100 pints/47 liters |
450 cfm @ 8 amps |
| Driair 2000 (200-pint) low grain refrigerant (LGR) |
110 pints/52 liters |
320 cfm @ 8 amps |
| Phoenix 200-pint low grain refrigerant (LGR) |
124 pints/61 liters |
250 cfm @ 7.2 amps |
| Dry Air Atlantic low grain refrigerant (LGR) |
140 pints/ 66 liters |
320 cfm @ 7.4 amps |
| Drizair 2400 (240-pint) low grain refrigerant (LGR) |
148 pints/70 liters |
365 cfm @ 11 amps |
| Phoenix 300-pint low grain refrigerant (LGR) |
176 pints/ 83 liters |
540 cfm @ 12 amps |
| Dritec 150-cfm desiccant |
48 pints/23 liters |
110 cfm @ 10 amps |
| Dritec 325-cfm desiccant |
135 pints/64 liters |
250 cfm @ 16 amps |
| Air Quest 1200 desiccant |
416 pints/ 196 liters |
900 cfm @ 25-40 amps |
