Dehumidifiers are rated according to how many litres of water they can remove from the surrounding air in 24hours, or how many squared metes they can keep dry. Be warned, some guidelines give fantastic sounding dehumidifying values which are set under test conditions with high humidity and high temperature. These guidelines are generally impossible to achieve in real life.

Knowing the cubic volume of the area you want to dehumidify will give you a good idea of which dehumidifier to use. If the size of the area you want to dehumidify is near the top end of a dehumidifiers stated capacity, hire or purchase the next size up.


Size selection of small dehumidifier by a rule of thumb:

  • A 12Litre/24hour dehumidifier will keep a 150sq ft x 8ft space at 55%RH
  • A 16Litre/24hour dehumidifier will keep a 200sq ft x 8ft space at 55% RH

55%RH is a general minimum requirement for most low level storage. For lower RH level like 45-50%RH, reduce the space/floor area by 35%. (The above sizing is based on an unventilated room. Rooms with air conditioning or ventilation systems are generally more difficult to estimate as they can either greatly reduce or increase the relative humidity (RH).


Energy Consumption

Keep energy consumption to a minimum by following these easy steps:

  • Hire or purchase a correctly sized dehumidifier
  • Hire or purchase the most energy efficient dehumidifier
  • Maintain the dehumidifier on a regular basis.
  • Operate dehumidifier according to manufacturers/suppliers instructions