What Size Dehumidifier Do I Need?

If you are a first-time buyer or new to the idea of using a dehumidifier, then your first question is, What size dehumidifier do I need? The truth is that every one of you will have different needs, room sizes, requirements, and humidity levels, which will determine which size dehumidifier you will need.

Humidity and moisture come from many sources:

  • Infiltration – damp through the fabric of the building, i.e., through floors or walls.
  • Occupants – people and animals exhale moisture as they breathe.
  • Outside – through open doors and windows.
  • Processes – dryers, vats of liquid, materials drying naturally.

The sum of all the possible sources of moisture is called the moisture load or humidity load. To calculate it, the indoor and outdoor humidity levels must be known, along with the amount of moisture contributed by occupants and processes. Once these are known, complex formulas are used to arrive at the size of the dehumidifier required.

A Simpler Way To Decide What Size Of Dehumidifier Is Needed

Step 1: Measure Your Area

First, measure the area you need to dehumidify and then check the manufacturer’s official specifications; in particular, look for what area of sq. footage they cover.

Step 2: Determine Your Humidity Level

You then need to determine how high your relative humidity level is and seek out just to what extent your humidity issues are. You can gather an accurate reading of this with the use of something called a Hygrometer.

Step 3: Use Our Table of Dehumidifier Size Chart Below

We have put together a table below, which should give you a ballpark figure of what pint size you may require. Bear in mind that these are guidelines only as it can be difficult to pinpoint exactly what size dehumidifier do I need, due to everyone’s unique circumstances and requirements.

Square FeetModerately DampVery DampWetVery Wet
500 sq.ft12 Pint14 Pint16 Pint18 Pint
1000 sq.ft16 Pint19 Pint22 Pint25 Pint
1500 sq.ft20 Pint24 Pint28 Pint32 Pint
2000 sq.ft24 Pint29 Pint34 Pint39 Pint
2500 sq.ft28 Pint34 Pint40 Pint46 Pint
3000 sq.ft32 Pint39 Pint46 Pint53 Pint

The table of dehumidifier size chart gives the minimum recommended size of dehumidifier in liters per day for a range of room sizes and conditions. It is important to note these figures assume a sealed room without any ventilation or occupants.

If you live in a coastal area, it would be wise to expect the area covered in the table above to be reduced by up to 50%. Meaning you may need to go up in pint-size. It is also advisable that you seek a pint intake of the higher caliber for highly humid areas such as basements.

For reliable dehumidification and drying, choose a dehumidifier with a higher output than the figure in the table; using the highest output dehumidifier available will generally not cause any problems.

Additional sources of moisture, such as vats of liquid, have also been ignored. If your intended application doesn’t meet these criteria, the table should not be used, and you should consult a specialist for further advice.

How To Choose the Right Dehumidifier – Hints & Tips

Go Larger Than Think You Require

Is bigger better for dehumidifier? It is always a wise decision to invest in a dehumidifier with a larger pint intake than you may need. The reasons for this are:

  1. It will remove moisture from the air much more efficiently over the same amount of area in comparison to a smaller model. The larger models are often much more energy-efficient full stop over their smaller cousins. They may require a larger energy output, but they will get the job done a lot better and quicker.
  2. They future-proof your home. Would you rather risk having a dehumidifier too small or not powerful enough to handle your requirements? Or one that handles your humidity effortlessly with room to spare?
  3. It will save you money: An example would be that if you are using a 30-pint dehumidifier in a highly humid basement that requires 40 or more pints to be removed, the unit will be in an on/off cycle, constantly trying to catch up; which increases your energy consumption. In comparison to a larger model reaching your desired humidity level and automatically shutting off.

What is a Good Middle Ground?

For most situations, we would say 30+ pints is an ideal sweet spot. However, everyone will have different requirements, so we do advise assessing your needs beforehand. If worst comes to worst and you buy one too large, you simply have a future-proof and efficient dehumidifier.

My Entire House Is Suffering From Humidity? What Can I Do?

If your house as a whole or a high amount of rooms are suffering, it may be a good idea to consider a whole-house dehumidifier. They are by far the better option to combat a humid household.

Practical Advice On Positioning And Using Portable Dehumidifiers

The room to be dehumidified should be made air-tight. This means doors and windows should be kept closed and ventilation holes sealed. Any cracks in the walls and ceiling should be filled, as should any gaps around doors and windows.

If one dehumidifier is used, position it in the middle of the room. For larger rooms where more units are used, space them equally around the room. Dehumidifiers should be positioned so that their airflow is unrestricted.

Faster Drying Using Ventilation Fans And Electric Fan Heaters

If faster drying is required, portable ventilation fans can be used with dehumidifiers to increase air circulation and the rate of evaporation.

Electric fan heaters can be used to raise the air temperature and increase the rate of evaporation. If electrical fan heaters are used, they must not blow in the direction of the dehumidifiers.

Note that drying out an area too quickly can lead to shrinkage and cracking; slow drying over several days is usually preferable to rapid drying.

Worked in IT for 10 years, specialising in computer measurement, resource and performance management and complex problem solving. Changed careers to HVACr in 2015.

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