Dehumidification

Dehumidification

A dehumidifier is a household appliance that reduces the level of humidity in the air, usually for health reasons, as humid air can cause mold and mildew to grow inside homes, which has various health risks. Relative humidity is preferably 30 to 50%.[1] Very high humidity levels are also unpleasant for human beings, can cause condensation and can make it hard to dry laundry or sleep.

Processes:

Mechanical/refrigerative

Mechanical/refrigerative dehumidifiers, the most common type, usually work by drawing moist air over a refrigerated coil with a small fan. Since the saturation vapor pressure of water decreases with decreasing temperature, the water in the air condenses, and drips into a collecting bucket. The air is then reheated by the warmer side of the refrigeration coil. This process works most effectively with higher ambient temperatures with a high dew point temperature. In cold climates, the process is less effective.[2] They are most effective at over 45% relative humidity, higher if the air is cold. [3]

Desiccative 

A desiccant dehumidifier is a device that employs a desiccant material to produce a dehumidification effect. As they are more effective for low-temperature and low (relative) humidity levels, they are generally used for these conditions instead of mechanical/refrigerative dehumidifiers - or are used in tandem with them.[3]
Desiccant materials have a high affinity for water vapor. An example of dessicant material is silica gel. Typically their moisture content is a function of the relative humidity of the surrounding air. Exposed to low relative humidities desiccant materials come to equilibrium at low moisture contents and exposure to high relative humidities results in equilibrium at high moisture contents. The process involves exposing the desiccant material to a high relative humidity air stream, allowing it to attract and retain some of the water vapor and then exposing the same desiccants to a lower relative humidity air stream which has the effect of drawing the retained moisture from the desiccant. The first air stream is the air that is being dehumidified while the second air stream is used only to regenerate the desiccant material so that it is ready to begin another cycle. Note that the first air stream's water vapor content is reduced while the second air stream's water vapor content is increased. Typically the low relative humidity air stream is air taken from any available source and heated to reduce its relative humidity. Hence
desiccant dehumidifiers consume heat energy to produce a dehumidifying effect.

In general a desiccant dehumidifier comprises four major components:
the component that holds the desiccant, of which there are several types;
1. a fan to move the air to be dehumidified (process air) through the desiccant holder;

2. a heater to heat the air that will be used to dry the desiccant (regeneration air);

3. a fan to move the low humidity air for drying the desiccant through the desiccant holder.

There are many different companies who have create dehumidifier like as Aprilaire.

Why Do I Need a Whole-House Dehumidifier?

Have you ever experienced any of the following uncomfortable and/or unhealthy conditions:

· Do you have trouble sleeping at night due to clammy skin or stuffiness in the air?

· Have you ever reduced the temperature setting because you're uncomfortable with the stuffy feeling?

· Have your floors or other surfaces ever felt sticky or “sweaty”?

· Are you concerned with mold and mildew growth in your home?

· Do you have musty odors or smells in any area of your home?

· Do you have condensation on your water pipes?

· Have you seen wet stains on walls or ceilings?

· Do you or a family member have allergies (over-moist air can encourage the growth of mold, bacteria, and dust mites—three commonly known household allergens).

Core Benefits

Every Aprilaire product provides important key benefits for your family and home.

Health

Excess indoor humidity provides the perfect breeding ground for mold, mildew, dust mites, bacteria and more. An Aprilaire Whole-House Dehumidifier combats these nasty home invaders, which are linked to asthma, allergies and other serious respiratory problems.

Comfort

Few things impact your home’s comfort more than excess indoor humidity. When you turn up your air conditioner to try and get rid of indoor stickiness, you’re really just making your home uncomfortably cool. An Aprilaire Dehumidifier allows you to wipe out that clammy feeling and say goodbye to musty odors. Plus optional built-in ventilation allows you to bring in conditioned, fresh outside air - ensuring your home remains properly ventilated.

Protection

Excess indoor humidity allows mold and mildew to thrive—ruining carpets, draperies, furniture and even clothing. It also can cause condensation build-up on windows, destroying their finishes and structural integrity. An Aprilaire Whole-House Dehumidifier helps protect your home and its contents by removing unnecessary moisture from your home’s air whenever it rises to an inappropriate and harmful level.

Energy Savings

Many homeowners turn up their air conditioning to get rid of the stickiness or clammy-feeling caused by high indoor humidity. An Aprilaire Whole-House Dehumidifier eliminates the need to over-cool, allowing for a higher thermostat setting for the same comfort level. And because it is more energy efficient than portable dehumidifiers, it uses less energy for the same amount of moisture removed.

Aprilaire Whole-House Dehumidifier Models There are two different models of Aprilaire Whole-Home Dehumidifiers that can solve your home’s excess humidity problems.

· Aprilaire Models 1710 Free Standing Dehumidifier

· Aprilaire Models 1750/1770 Whole-House Dehumidifiers The only truly effective solutions for total home excess moisture control.

Humidification

Humidification

A humidifier is a household appliance that increases humidity (moisture) in a single room or in the entire home. There are point-of-use humidifiers, which are commonly used to humidify a single room, and whole-house or furnace humidifiers, which connect to a home's HVAC system to provide humidity to the entire house.

Evaporative humidifiers:The most common humidifier, an "evaporative" or "wick humidifier", consists of just a few basic parts: a reservoir, wick and fan.
WickThe wick is a filter that absorbs water from the reservoir. Evaporation of water from the wick is dependent on relative humidity. A room with low humidity will have a higher evaporation rate compared to a room with high humidity. Therefore, this type of humidifier is self-regulating: As the humidity of the room increases, the water vapor output naturally decreases. These wicks regularly need cleaning and replacement — if this does not happen, the humidifier stops humidifying the area it is in and the water in the tank remains at the same level.
Fan
The fan is adjacent to the wick and blows air onto the wick, thus aiding in the evaporation of the water within

Other types of humidifiers:Other types of humidifiers include:
Vaporizer (Steam Humidifier) (Warm Mist Humidifier) — Boils water, releasing steam and moisture into the air. A medicated inhalant can also be added to the steam vapor to help reduce coughs. Vaporizers are more healthful[1] than cool mist types of humidifiers because steam is sterile and free from minerals. Vaporizers use more electricity to boil the water.
Impeller Humidifier (Cool Mist Humidifier) — A rotating disc flings water at a diffuser, which breaks the water into fine droplets that float into the air.
Ultrasonic Humidifier — A metal diaphragm vibrating at an ultrasonic frequency creates water droplets that silently exit the humidifier in the form of a cool fog. Ultrasonic Humidifiers should be cleaned regularly to avoid bacterial contamination which may be projected into the air.

Disadvantages and risks:
The use of a humidifier can allow the reproduction of dust mites or the growth of harmful mold, which can be especially harmful for children and the elderly. The relative humidity should be kept between 30% and 50%. [2]. Can also cause Hypersensitivity pneumonitis (humidifier lung) [3]
Some humidifiers now use Microban technology to reduce mold and bacteria growth within the humidifier.
The EPA provides detailed information of the risks as well as recommended maintenance procedures[1]. One of the main concerns cited by EPA regarding ultrasonic or impeller humidifiers is a "white dust" that has been reported by some consumers, which usually spreads over furniture, is attracted to static electricity generating devices such as CRT monitors and possibly affects the lungs. Although EPA does not explain the "white dust" generation mechanism, which is undesired and potentially harmful, some manufacturers claim that not only is it beneficial but also that it is intentionally produced. It is claimed[who?] that the process is associated to the release of negatively charged ions which attach themselves to allergens and dust particles neutralizing and purifying the air, protecting against molds, mildews, fungi, bacteria, viruses and dust mites.

Whole-Home Humidification vs. Portable

Too much humidity can be as much of a problem as too little humidity. Unlike portable units the Aprilaire Whole-Home Humidifier continually monitors relative humidity levels in your home, then works to deliver the right amount of moisture (click here to view an Optimum Relative Humidity Chart) —never too much or too little— to your entire house. Aprilaire Humidifiers don't require the daily cleaning and disinfecting that many portable units require and you never need to worry about the risk of microbial organism growth due to standing water.

“Humidifiers are commonly used in homes to relieve the physical discomforts of dry nose, throat, lips, and skin. The moisture they add to dry air also helps alleviate common nuisances brought on by winter heating, such as static electricity, splitting woodwork, and cracks in paint and furniture.”
Humidistat:A controller that measures and controls relative humidity. A humidistat may be used to control either humidifying or dehumidifying equipment by the regulation of electric or pneumatic switches, valves, or dampers.
An electronic humidistat includes a sensing element and a relay amplifier. The sensing element consists of alternate metal conductors on a small flat plate. An increase or decrease of the relative humidity causes a decrease or increase in the electrical resistance between the two sets of conductors and the change in resistance is measured by the relay amplifier.

There are many different companies who have create humidifier like as Aprilaire.

How It Works:
An Aprilaire Whole-House Humidifier is installed directly to your central new or existing heating and cooling system. Humidity is introduced into your home’s air in the form of water vapor, which prevents minerals from entering the air in your home and potentially into your lungs. Water is supplied to the distribution tray, allowing it to flow evenly across the Aprilaire Water Panel®. The resulting humidified air is then distributed via your heating and cooling system ductwork throughout your home.

Core Benefits:
Every Aprilaire product provides these important key benefits for your family and home.
Health An Aprilaire Whole-House Humidifier can reduce the chance of upper respiratory problems. “Humidity reduces the incidence of respiratory infections and speeds recovery from the common cold.”—William J. Hitschler, MD, Archives of Otolaryngology.Comfort When the air in your home becomes too dry, your body is robbed of precious moisture, leaving you and your family with dry, itchy skin, and dry nose and throat symptoms. An Aprilaire Whole-House Humidifier can help alleviate all of these uncomfortable symptoms and more.Protection Dry air pulls moisture from walls and hardwood floors which leads to damaging, unsightly cracks. Valuable furniture, artwork and electronics are also subject to the adverse effects of dry air. An Aprilaire Whole-House Humidifier can help protect your home and its contents by supplying the correct amount of moisture to your home’s air.Energy Savings Most homeowners turn up the thermostat because they feel cold. An Aprilaire Whole-House Humidifier allows you to feel warmer at lower thermostat settings, saving up to 4% on your heating bill for every degree you lower your thermostat, according to the EPA.

Aprilaire Whole-House Humidifier Models:There are several models of Aprilaire Whole-House Humidifiers, designed to satisfy your family’s specific needs.
· Aprilaire Model 700A Whole-House Humidifier This humidifier features a powered fan to increase air flow for the highest capacity available. Perfect for larger homes.
· Aprilaire Model 600A Whole-House Humidifier Features a built-in bypass damper, which means fewer parts to install.
· Aprilaire Model 500A Whole-House Humidifier This humidifier is designed for use in smaller homes.
· Aprilaire Model 400A Whole-House Humidifier This humidifier utilizes new evaporative technology to minimize the amount of water used.
· Aprilaire Models 350/360 Whole-House Humidifiers These humidifiers are specifically designed for installation in homes with radiators or baseboard heat.