Dehumidifiers
| If your home feels damp, or if you have notice symptoms of high humidity including mould, itchy skin, musty odors, condensation on windows, or rotting wood, then you might want to consider a dehumidifier  to control moisture levels. There are dehumidifiers for all purposes, from small flats to industrial strength. There are three main forms on the market: heat pump dehumidifiers; chemically absorbent dehumidifiers; and dehumidifying ventilators . This guide primarily concerns the first type, the heat pump dehumidifier.
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- Unit Size
- Most units are described by how much water they can remove from a given area, sometimes based on temperature.
- It is usually better to have a more powerful dehumidifier than you need -- it will remove moisture more quickly and will require fewer emptyings.
- Some dehumidifiers are small enough to place in the corner of a living room. Others need to be out of the way and close to the main problem source, such as in a basement.
- Low power dehumidifiers can work in small spaces from 500-1000 sq. feet, which remove up to 8 litres of water in 24 hours. Meanwhile, high power models can work in spaces up to a whopping 4000 sq. feet and can remove more than 45 litres of water a day.
- Your Climate
- Will windows be left open in the area where the dehumidifier will be placed? Dehumidifiers, like air conditioners, work better when the windows are closed.
- For homes near the water, you will want a more powerful model.
- Severity of the Moisture Problem
- Large problems require large investments. These dehumidifiers are often quite noisy and much heavier because they are meant to be more powerful.
- Consider how long the problem has existed. Is it relatively new or has this been a chronic problem? Sometimes for constant moisture issues, a large model that can be placed in the basement is the only solution.
- Usage Location
- Basement, crawl space, or bedroom?
- Consider looks, size, and power to get the best fit. Also, if the dehumidifier is going to be running non-stop, it is probably because there is a large moisture problem. Opt for a large dehumidifier that you can leave running in the basement or other discreet location.
- Anything that will be in the living room or bedroom should be tested for noise level.
- Easy to Empty?
- All that water removed from the air has to go somewhere.
- All models will have some kind of bucket that can be removed and emptied. This bucket is often about half of the maximum volume of water that can be removed in one day.
- If you get a smaller model, it may need to be emptied once or twice a day.
- Some models have the option of attaching a drainage hose; if you can't be there to empty it, this might be an important option for you.
- Some models have an auto-shutoff feature as well, but if you have high humidity you may prefer a self-draining tank.
- Because some of the larger models can be messy, it is advised to consider placement carefully. Avoid areas with carpet, and unsealed hardwood floors, or any other storage area that contains other valuables that can be damaged by water. Usually small models are cleaner and won't cause as much of trouble.
- Other Features
- Electronic humidistat -- lets you program the humidity level you want.
- Auto-defrost controls
- Design and appearance
- Warranty
- Portability (wheels, grips, and handles)
- LCD displays and monitors for humidity control and automatic shut-off.
Purchase Cost vs. Maintenance Cost
Cost range -- £30 and up for smaller models and from £100 for larger capacities. Cost increases as more features are added. Plus, for larger, more heavy-duty models for the whole house or basements, be prepared to spend at least £400. Some commercial or industrial dehumidifiers can cost upwards of £2500. However, unless you have a serious humidity problem or have suffered severe water damage, most of these machines are probably overkill for the home.
Maintenance cost -- includes electric bills. Be careful to look at the EF, or Efficiency Factor, which measures amount of moisture that can be removed compared to operating costs. While higher cost models are initially more expensive, they are less costly in the long run.
Cleaning Procedures -- dehumidifiers need to be properly maintained to ensure quality performance. The coils need to be vacuumed twice a year and the internal filters need to be cleaned every two weeks, or as often as they get dirty. Also, water needs to be drained on a regular basis, depending on how often you run your dehumidifier and on how big the drainage bucket is. (If you have an auto-drain feature, of course, you don't need to worry about this.)
Alternatives
- For relatively little money, you can purchase a bucket of calcium chloride crystals (under brand names such as "Hydrium ") which will readily absorb water from the air.
- Calcium chloride is a highly hygroscopic salt, meaning that it will absorb a lot of water -- so much, in fact, that it will dissolve itself if left in the open.
- These are usually only suitable for small areas, such as as closets or storage areas.
- Require periodic water removal and occasional refills.
- Air conditioners will also remove humidity from the air.
- Some dehumidifiers will also warm the area by a few degrees; air conditioners will cool it.
- There are also whole-house dehumidifiers, which may be a good choice if your house feels muggy and damp year-round.
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