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If you have ever experienced a water damage claim at your home or business, you are familiar with all the equipment that it takes to properly dry out a structure. Depending on the type of water loss, you will more than likely have several different pieces of drying equipment positioned across the damaged area to dry the structure. One of the most important pieces of drying equipment used by restoration professionals is a dehumidifier. There are three different types of dehumidifiers that are most commonly used in a water restoration project: Conventional Refrigerant, Low Grain Refrigerant (LGR) and Desiccant.

Conventional Refrigerant Dehumidifiers are the most basic portable dehumidifiers used in the restoration industry.
Refrigerants remove water from the air by condensing the air on cold coils, much like a cold soda can on a humid day.
Because of this, they operate most efficiently in very humid conditions, and between 70 degrees and 90 degrees Fahrenheit.
In ideal conditions, refrigerants are effective in lowering high humidity to a safe level of 40% relative humidity (RH).
Conventional refrigerants do have limitations such as lower water removal rates, low air processing, and they are not able to adequately reduce humidity levels in situations with large amounts of bound water.

LGR Dehumidifiers are the most common type of portable dehumidifier used by water restoration professionals. LGR is an acronym for Low Grain Refrigerant units. Unlike conventional refrigerants, the LGR dehumidifier will continue to remove water below 55 grains per pound or even 40 grains per pound. LGR dehumidifiers contain an enhanced refrigeration system that can dry a space to lower humidity than conventional dehumidifiers. The LGR units feature a double cooling action, as it moves air over a cold surface and a cooling device. They pre cool the incoming air stream with a heat exchanger or heat pipe technology, which removes more water per kilowatt of electricity then its conventional counterpart. It then forces the water vapor to condense at a greater degree of efficiency compared to a standard dehumidifier.

Desiccant Dehumidifiers offer sophisticated technology that uses chemical attraction instead of condensation to extract water. When used correctly, they produce the driest air (lowest GPP) of any dehumidifier and are capable of most closely approximating desert like drying conditions. A desiccant dehumidifier uses a material that naturally absorbs water from the air. There are various desiccant materials, but the most common is silica gel, which is actually a granular substance and not a gel. Desiccant dehumidifiers work by drawing in damp air, absorbing the moisture, then blowing out dry air. The dry air encourages evaporation throughout the area. The desiccant dehumidifier employs a wheel containing the silica gel. As the wheel turns, the gel cycles continuously and repeatedly through absorption and heating stages. The heating stage expels the absorbed moisture from the gel. Desiccant dehumidifiers are great for dense materials like hardwood floors, lath and plaster walls, concrete, or if location temperatures are cooler than 60 degrees Fahrenheit. Desiccants come in all sizes from small, suitcase sized to large trailer mounted units. The size of a desiccant is measured in CMF’s or cubic feet per minute, which is the speed in which it will perform an air exchange.

The type of equipment used on a water restoration project will vary, as every job is uniquely different. An experienced restoration contractor will be able to assess the project and bring the right equipment to make sure you job is dried as efficiently as possible. Until next time my friends, be prepared and stay safe.

Reference: “LGR Dehumidifiers and how they fit the water‐damage/restoration industry” by B‐Air and “How to choose the right dehumidifier for water damage restoration” by Jon‐don