Can a Dehumidifier Really Be Too Big For a Space? (Detailed)

Selecting accurately sized dehumidifier is very important for effective removal of humidity, to protect you, your home and your appliances. A less powerful dehumidifier will be insufficient for removing required amount of moisture from the environment. But what about a dehumidifier that is bigger and larger for a required space. Can a dehumidifier be really too big?

A dehumidifier too big for your room or space can either be useful by reducing electricity consumption and noise or inefficient and inconvenient by causing higher power usage, more noise and excessive dryness. This depends on duration of operation, target humidity and automaticity of unit.

Well, that was the short answer. But let’s find out will it really be better, particularly for you. I have written this article specifically covering this query, so that in the end you can come to the conclusion, either it will improve functionality, effectiveness and efficiency or reduce it.

How To Evaluate Required Dehumidifier Capacity for Your Space

Dehumidifiers are sized based upon the amount of humidity they extract from the environment over the period of 24 hours. This quantity of water is measured in pints.

For example, if your dehumidifier is 50 pints, this means it will extract 50 pints (23.6 liters) of water in 24 hours.

Note: Previously this testing was performed with temperature of 60°F and relative humidity 80%. These standards were updated in 2020, temperature 65°F and relative humidity 60%, to reflect realistic environmental conditions.

Choosing right size for your room is easy. Simply go through the steps below and you will end up with the right capacity of dehumidifier you need:

  1. Make a rough estimate of average relative humidity in the space where you need to use your dehumidifier. Having problem estimating, these indicators below will help give you an idea:
    • Air feels a little heavy (50-60% RH)
    • Musty and moldy smell now and then (60-70% RH)
    • Walls and floors have wet stains (70-80% RH)
    • Water seepage with apparent mold (80-100% RH)
    • You can also use a hygrometer for measuring humidity. By the way, RH above stands for Relative Humidity.
  2. Check temperature of the room where your dehumidifier will operate. Make sure it is above 60°F. Actually, if you run it below this limit of temperature, it may result in frosting of dehumidifier coils.
    Frosting will cause your dehumidifier to intermittently shut OFF and ON and keep filling it quickly, even when dehumidifier is off.
  3. Finally, for the area of the space in your home that you want to dehumidify and estimated relative humidity there, use the table below from AHAM (Association of Home Appliance Manufacturers) to determine required dehumidifier capacity for your needs.
Relative Humidity300 sq ft space500 sq ft space800 sq ft space1,200 sq ft space

30 Pint (Old Standard)
20 Pint (New Standard)
45 Pint (Old Standard)
30 Pint (New Standard)
60 Pint (Old Standard)
40 Pint (New Standard)
70 Pint (Old Standard)
50 Pint (New Standard)

30 Pint (Old Standard)
20 Pint (New Standard)
45 Pint (Old Standard)
30 Pint (New Standard)
60 Pint (Old Standard)
40 Pint (New Standard)
70 Pint (Old Standard)
50 Pint (New Standard)
70-80%40 Pint (Old Standard)
25 Pint (New Standard)
50 Pint (Old Standard)
30 Pint (New Standard)
65 Pint (Old Standard)
45 Pint (New Standard)
80 Pint (Old Standard)
55 Pint (New Standard)

45 Pint (Old Standard)
30 Pint (New Standard)
60 Pint (Old Standard)
40 Pint (New Standard)
70 Pint (Old Standard)
50 Pint (New Standard)
90 Pint (Old Standard)
60 Pint (New Standard)

Problems with Dehumidifier Too Large-Sized for A Room

Generally, it is a good idea to buy a dehumidifier that is a little larger than the requirement. Problems may only arise if the size of your unit is prominently higher than normal or recommended.

If your dehumidifier is a lot bigger than the recommend size, according to the table above, it may increase effectiveness, efficiency and convenience or reduce it.

These are the variables that decide the impact of a large sized dehumidifier:

  • Extent of drop in relative humidity you need
  • Automaticity of dehumidifier operation
  • Mobility of dehumidifier
  • Time duration of dehumidifier operation

I will discuss how these variables affect dehumidifier operation and what kind of impact they will have on various desirable and undesirable aspects of it.

Electricity Consumption

By intuition, a dehumidifier with larger capacity should use more electricity compared to normal sized dehumidifier. However, this is not necessarily true. In fact, usually by using a bigger dehumidifier you will actually reduce power intake.

Well, how is that? Dehumidifier turn Off after desired humidity is achieved in a space. If you have a higher capacity dehumidifier than required, it will complete required dehumidification quicker, turn Off early and save you power.

But there is a catch. There are two scenarios in which larger capacity dehumidifier would actually have a higher electricity consumption.

  1. If you don’t have an automated dehumidifier and you can only select the level of operation (high, medium, low), or humidistat is faulty. Your dehumidifier will constantly run without turning off quicker and for the same duration of time it will use more power.
  2. Very low or practically unattainable value of relative humidity, or let’s say in case of water damage or flooded basement, will cause your dehumidifier to never turn Off. This will spike electric power usage in comparison to normal-sized dehumidifier.

Noise Made By Dehumidifier

A refrigerant dehumidifier has mainly two moving components: compressor and fan. When dehumidifier is running, most of the sound among these two is generated by fan operation.

With a bigger dehumidifier, fan will need to run at lower capacity to perform required dehumidification. This means increased size may actually reduce noise from your dehumidifier.

Quicker operation also means that fan will turn off quicker. Thereby, noise will stay for a smaller time with less intensity.

Note: In case your dehumidifier does not have humidity control and automated fan speed control, it will generate louder noise and run for same duration of time compared to normal-sized dehumidifier.

The solution is to manually adjust fan speed considering oversizing of dehumidifier compared to space.

Excessive Dryness

This again will be a problem with manual constant operation dehumidifier lacking humidity control and automation. Dehumidifier will keep functioning regardless of the desired relative humidity and cause excessive dryness.

Weight and Space Requirements

Generally, a larger capacity dehumidifier will have more weight and cover more space. This will be a problem for smaller rooms mainly. By increased weight, most of the inconvenience would be in mobility. If you are using same dehumidifier for more than one location in your home, a bigger dehumidifier would make movability difficult.

Should You Avoid Using Large-Sized Dehumidifier?

As I said earlier, you may use a dehumidifier of larger capacity than required, in fact, it may be even better. But when the size is a lot bigger for a space, that is when you should take into account other factors.

I recommend that you go through factors I discussed earlier to realize either an oversized unit will improve dehumidification, efficiency and ease for you or reduce it.