The role dehumidifiers play in drying a Columbus, Oh home, and how the efficiency is measured!
When drying a structure, the ultimate goal is to remove moisture that does not belong in the building material, be it carpet, drywall, cabinets, or any other material used in the structure. As outlined here, extraction of water is an important aspect of this. After water has been extracted, how can the remaining moisture issues be resolved? Air movement and dehumidification are the most common answers to this question. Air movers are discussed in more detail here, and specialty equipment that may not quite fall under either category is discussed here.
We have all heard the weather man tell us what the likely temperature and humidity will be in a forecast, but few of us have thought about what this means, and how it applies to drying a home. Before I get into the dehumidifiers themselves some basic understanding of temperature and humidity are important.
Temperature is usually thought of as hot or cold or comfortable as it relates to us, but for the purposes of dehumidifiers it is more important to think about it as a vessel for carrying water in the air. As water mitigation specialists, we want to know what the weight of water in the air is so that it can be compared at any temperature. GPP or “grains per pound” is used for this. With this in mind, let’s go back to the container, the temperature. At 0°F and 100% relative humidity the GPP is 6, but at 80°F it only takes 4% relative humidity to get a GPP of 6. Refrigerant type dehumidifiers use this principal to remove moisture in the air by cooling it off to a point where the air cannot hold the excess moisture, and it is then drained off as condensation. Another principal of some dehumidifiers is a more chemical one. Desiccant dehumidifiers have wheels of desiccant filled cells that capture moisture at the temperature of the space that the air is captured from. The moisture is then cooked off of the desiccant when the wheel passes that desiccant past a heater. The hot damp air is exhausted away.
Refrigerant dehumidifiers are much more common because they tend to be cheaper and more power efficient to use. When looking for well rounded dehumidifiers most restoration companies start by looking at Phoenix products or Dri-Eaz products. Some desiccant models have their uses too, and can be an important piece of equipment to have access to in some circumstances. For our purposes here I will focus on refrigerant dehumidifiers, desiccant dehumidifiers as they apply to commercial applications are mentioned here.
Restoration company refrigerant dehumidifiers use what is called an AHAM rating to determine how efficient it is. The AHAM rating simply identifies how many pints of water that dehumidifier can remove in 24 hours if it is put in a chamber with a temperature of 80°F and a relative humidity of 60%. This reflects a more real world condition as opposed to the conditions commonly used to market home dehumidifiers at a local retail store. Even dehumidifiers specifically used for the restoration industry come in a large variety of models, but because they all use the AHAM rating it isn’t very difficult to determine how many dehumidifiers are needed in a defined space. Basically our restoration technicians will measure the cubic space of air that will be processed by the dehumidifier and along with the factor of where the water came from and what portion of a structure is affected can decide how many AHAM pint will be needed in a 24 hour period. That is then used to set the dehumidifiers, because the total AHAM ratings of the combined dehumidifiers in the space should equal or exceed the AHAM pints needed for the 24 hour period.
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