If you have a large, humid room, you know getting an appropriately sized dehumidifier is important. The efficiency of the device should be a top consideration when shopping for a dehumidifier. But how can you make sure the unit is suitable for your needs?
The PPD or Pints Per Day rating can help you measure the ability of the dehumidifier to remove water vapor. It specifically tells you the amount of excess moisture the device can draw out from the air. It is the standard used to evaluate the efficiency of the dehumidifier.
However, the PPD rating can vary based on specific conditions, which we will cover below. We’ll also teach you the background and history behind this efficiency standard. Finally, we’ll share tips on how to find the correct dehumidifier size for your room.
What Is PPD Rating in Dehumidifiers?
PPD stands for Pints Per Day. It refers to how many pints of water the dehumidifier can remove from the air within 24 hours under specific conditions. It is a standard measurement of efficiency for conventional dehumidifiers.
Dehumidifiers are designed to reduce moisture from the air in a room when humidity is too high. Reducing moisture can help prevent growth of mold, musty smells, and the spread of certain allergens. However, improperly sized devices can trigger different issues instead of addressing them.
The PPD rating helps you choose an appropriately sized model for your needs. For example, if you have a very humid room, you want a dehumidifier with a higher PPD rating for efficient moisture removal. In contrast, selecting a lower PPD rating is best if you have a dry space with cold air.
PPD Rating Background
Dehumidifiers must pass standard tests before home appliance manufacturers can sell them.
The U.S. Department of Energy uses two primary performance ratings—capacity and the energy efficiency metric.
Let’s talk about capacity first, which refers to the amount of water removed daily. In other words, it is the PPD rating of conventional dehumidifiers.
The American Home and Appliance Manufacturers, or AHAM in short, examines dehumidifiers under specific conditions. These circumstances used to be 60% humidity and 80 degrees Fahrenheit. For example, if you have a commercial dehumidifier with a 70 PPD rating, it removes up to 70 pints of water per day once ideal conditions are met.
AHAM chose these figures because they accurately represent real-world situations in which dehumidifiers are used. However, in 2019, the standard testing environment had changed (more on this topic later).
Besides the PPD rating of AHAM, some dehumidifiers undergo the Saturation test. It uses extreme conditions at 90% humidity and 90 degrees Fahrenheit. These do not depict actual circumstances in which dehumidifiers will be used. The main purpose of the Saturation test is to determine the maximum amount of moisture that could be removed in one day.
That said, the Saturation test can be useful if you need to extract a large amount of water vapor in the air. Popular examples include a flooded basement and an industrial setting with constant moisture. These usually require the unit to run continuously over 24 hours.
Energy efficiency indicates the amount of water a conventional dehumidifier can remove per kilowatt-hour of energy used. It uses the Integrated Energy Factor (IEF) as the metric for efficiency.
IEF includes the energy the device consumes when it has cycled off. It offers an accurate representation of how much energy is used to reduce humid air.
PPD Rating Changes
As previously mentioned, the environment in which the dehumidifiers are tested changed in 2019.
Before 2019, dehumidifiers undergo a test under 60% humidity and 80 degrees Fahrenheit. Most dehumidifiers are available in 30-, 50-, and 70-pint capacity or PPD ratings.
Today, all units must be tested at 60% humidity and 65 degrees Fahrenheit. It is 15 degrees lower than in the past.
DOE decided to use cooler, more realistic conditions that are similar to a basement setting. Cooler temperatures mean there is less moisture to remove from the air. As such, the capacities of dehumidifiers have decreased. The standard PPD ratings are now 20-, 30- and 50-pint instead of 30-, 50-, and 70-pint models (which are tested at 80 degrees Fahrenheit).
So, what do these changes mean for consumers?
Nothing much, really.
As long as you know the room size you intend to dehumidify, you can find the suitable unit for your needs.
That is because the dehumidifiers themselves didn’t change. The internal components are more or less the same.
So, if you see a 70-pint model, it is likely that it’s still using the old testing conditions. The new 50-pint units operate similarly as the old 70-pint devices.
What Size Dehumidifier Do I Need?
To determine the size of dehumidifier you need, you must consider the following factors.
- Room size – The larger the room, the higher the PPD rating you need. Make sure to calculate the square footage of the area where you intend to use the dehumidifier. If it is less than 500 square feet, a unit between 20 and 30 PPD is recommended. Rooms more than a thousand feet require 50-pint models to remove moisture.
- Current humidity levels – Consider the existing humidity levels in the room. If it is very humid, you need a dehumidifier with a higher capacity. Basements, laundry rooms, and bathrooms are examples of areas with high humidity.
- Number of people in an area – You must also think about the number of individuals who will spend time in one space. For example, having five people in the dining area increases the chances of releasing moisture into the air. Your best bet is to use a dehumidifier with higher PPD rating to reduce relative humidity.
The PPD rating is the maximum volume of water the dehumidifier will remove per day under specific conditions. Knowing the Pints Per Day rating of the device is important to ensure it can maintain your desired humidity level. It can also indicate the efficiency of the device.
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