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Rule of thumb formulas for water damage restoration

7 min read
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Even for water damage restoration experts with decades of experience, it is nearly impossible to calculate every dehumidification requirement with 100% accuracy.

There are many factors that need to be taken into account in order to determine the best dehumidification load for your water damage restoration project. And while every situation is different, the empirical data below provides a helpful rule of thumb guide to work from.

W refers to the amount of water drawn from the air in grams per hour (g/hour).

V refers to the volume of the room in m3.

Please note that concerning drying out a newly constructed building it all comes down to the specific building materials used for walls, floors and roofs. The water content of various building materials differ so much that a simple rule of thumb would not make sense.

1. Establishing a comfortable indoor climate

If the desired RH-value is to be approx. 50% RH use this formula:

W = V * 2.0 (g/hour)

Example: V = 500m3> W = 2.0 * 500 = 1,000g/hour.

Recommendation: Two CDT 40 units. Capacity: 0.65 litre/hour at 20ºC/50% RH.

2. Preserve and protect goods and materials

If the desired RH-value is to be approx. 50% RH use this formula:

W = V * 1.2 (g/hour)

Example: V = 450m3 > W = 1.2 * 450 = 540g/hour

Recommendation: CDT 40. Capacity: 0.65 litre/hour at 20ºC/50% RH.

3. Repair water damage

Assuming a drying process of 8-12 days and an average condition of t = 20ºC/50% RH (starting at 60% RH ending at 40% RH) use this formula:

W = V * 4.0 (g/hour)

Example: V = 280m3 > W = 4 * 280 = 1,120g/hour

Recommendation: Two CDT 40S units. Capacity pr. unit: 0.60 litre/hour at 20ºC/50% RH. We recommend that you use S-models with extra air volume and built-in 1kW heaters to force the evaporation and speed up the dehumidification process when dealing with water damage.

Room volume (V)
CDT 30S
CDT 40S
CDT 60
CDT 90
< 200m3
2 units
1 unit
1 unit
1 unit
200m3 - 300m3
3 units
2 units
2 units
1 unit
300m3 - 500m3
5 units
3 units
3 units
2 units
500m3 - 750m3
7 units
4 units
3 units
2 units

For more advice on water damage restoration and choosing the best system for your requirements, don’t hesitate to get in touch.

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