Summary: Some insect control can best be done by controlling the environment. Booklice, for example, require high humidity, so reducing the humidity levels below fifty-percent will make the environment less hospitable for psocid. This exterminator did some online searches for the best portable dehumidifier and came up with these results.
First, you need to understand what a dehumidifier is supposed to do. Hopefully, the dehumidifier removes water vapor from the air, lowering the humidity. Air conditioning units lower humidity while they cool the air, but during hot weather, not even the best of air conditioning units can totally remove sufficient amounts of water vapor. Therefore, dehumidifiers act to maintain dry air, helping the AC to work more efficiently, saving you money on cooling bills, too.
Dry air also helps to control mold and mildew, thus reducing allergic reactions for people who are mold sensitive. The dehumidifier works especially well in areas of high humidity such as bathrooms, kitchens and basements. Think about all the mold and mildew products you use in your shower to keep it from looking like the underside of a rock in a stream. All green and slimy.
Here's how a dehumidifier works. It has a hot coil and a cold coil in the same box. A fan draws room air over the cold coil. This causes water vapor to condense like when moisture appears on the outside of a cold glass. The moisture drips into a collection bucket inside the dehumidifier. As the air is pushed through the unit the dry air passes through a hot coil that heats it back up to the same temperature that it was when it entered the dehumidifier. It's sort of an air conditioner with an extra coil that reheats the air.
So, what size dehumidifier is best? Manufacturers of dehumidifiers will tell you what size room a particular unit is designed for, but humidity levels can vary. A more accurate way to determine the size dehumidifier you need is by figuring out how much moisture do you need to remove. Homes with leaky basements or roofs will need a lot more humidity removed than a home without these problems so a larger unit will serve the purpose. If the humidity problem is less severe, a smaller unit will do.
You should probably not try to resolve serious moisture with a room dehumidifier alone. You will never win that battle. The dehumidifier will never meet the demand and you'll end up over-working the dehumidifier and wearing it out long before its advertised life span. A better road would be to fix the roof or plumbing leak and then determine if additional dehumidification is required.
Okay! That said, here's what various consumer guides have to say about portable dehumidifiers. ConsumerGuide favors the Kenmore 70 Pint 54701 unit. This model, sold by Sears, pulls 70 pints of moisture from the air every twenty-four hours. It comes with a 22 pint bucket, which means you'll be visiting your new unit several times a day if you have a lot of dehumidifying to do.
ConsumerSearch likes the Soleus Air CFM 40E. This is a smaller 40 pint per day unit that holds only 12.5 pints. Works great, but it would be the wrong unit if you need much larger capacities. If that is the case, they also like the Frigidaire FDF70S1 which pulls 70 pints per day. However, once again, it has a small collection tank holding only 17 pints. You can set it up to drain into a floor drain. Another down side is that the unit is pretty loud when it is running. A real conversation killer. Amazon.com also likes the Frigidaire unit.
For small places like an RV or storage area, ConsumerSearch likes the Eva-Dry EDV-E-500. It does not use electricity, but instead uses crystals to absorb 8 to 10 ounces of water over several weeks. This is more of a closet unit than anything else.
There are hundreds of sites selling and reviewing dehumidifiers. They all make claims about their products and they all give a one-year warranty, for the most part. That should tell you something about the quality of these units. They are not comparable to whole house dehumidifiers and are not meant to last forever. They usually run continuously and are somewhat noisy. If you need more than a part-time dehumidifier you would be better off looking at having one installed in your HVAC system.