Dehumidifier

[1] This is done usually for health or thermal comfort reasons or to eliminate musty odor and to prevent the growth of mildew by extracting water from the air.

Large dehumidifiers are used in commercial buildings such as indoor ice rinks[2] and swimming pools, as well as manufacturing plants or storage warehouses.

Cheap domestic units contain single-use hydrophilic substance cartridges, gel, or powder.

These newer technologies may aim to address smaller system sizes or reach superior performance.

The dehumidification process is the inverse of adding water to the room with an evaporative cooler, and instead releases heat.

The balance of the air then passes into the evaporator coil of the heat pump where it is cooled and the moisture is condensed.

Instead, the refrigerant is pumped by the compressor to a condenser which is located outside the room to be conditioned, and the heat is then released to the outside air.

To be effective as a dehumidifier, an air conditioner must be designed or modified so that most or all of the water that condenses is drained away in liquid form, rather than re-evaporated.

Even if condensate is drained, a modified air conditioner is still less efficient than a single-purpose appliance with a design optimized for dehumidification.

In extreme cases, the ice can deform or distort mechanical elements, causing permanent damage.

An alternative design senses the impeded airflow and shuts off the cooling coils in a similar manner.

Thermoelectric dehumidifiers use a Peltier heat pump to cool a surface and condense water vapor from the air.

The most efficient configurations save energy by using two membranes that isolate a vacuum pump from ambient air.

An ionic membrane can be used to move humidity into or out of a sealed enclosure, using chemical reactions rather than condensation or selective materials.

This approach provides a low power, steady-state dehumidifier for enclosed areas where long-term maintenance is difficult.

SPE systems generally do not have high dehydration capacities, but because the water vapor is removed through electrolysis, the process is maintenance-free.

SPE dehumidifiers are typically used to protect sensitive electrical components, medical equipment, museum specimens, or scientific apparatus from humid environments.

The SPE consists of a proton-conductive solid polymer electrolyte and porous electrodes with a catalytic layer composed of noble metal particles.

Today, warm condensation technology, based on the concept of over-saturated steam inside a closed environment,[clarification needed] makes it possible to dehumidify air at sub-zero temperatures.

In a warm humid environment, these buckets will generally fill with water in 8–12 hours, and may need to be manually emptied and replaced several times per day to ensure continued operation.

Many portable dehumidifiers can also be adapted to connect the condensate drip output directly to a drain via a hose.

Some dehumidifier models can tie into plumbing drains or use a built-in water pump to empty themselves as they collect moisture.

Alternatively, a separate condensate pump may be used to move collected water to a disposal location, when gravity drainage is not possible.

Central air conditioning units typically need to be connected to a drain, because frequent manual emptying of multiple containers of condensate water extracted by such systems is impractical.

Air handlers located below grade level, e.g. the basement of a house, may need to use a condensate pump to lift the water to a surface drain.

The devices are primarily intended to produce pure water, and the dehumidifying effect is viewed as secondary to their operation.

Condensate collection trays and containers may need occasional cleaning to remove debris buildup and prevent clogging of drainage passages, which can cause water leakage and overflow; if large amounts of certain particulates or dust are collected, then this may need to be performed frequently to avoid microbial growth.

[20] Dehumidification within buildings can control: Dehumidifiers are also used in construction areas and renovations of indoor space to remove excess humidity or mildew.