Introducing Dehumidifiers and their Function
Dehumidifiers use a heat pump (similar to an air conditioner's heat pump) or chemical adsorbents to remove moisture from the air without cooling the air.
A heat pump dehumidifier uses a fan to draw indoor air over a heat exchange coil. The coil is almost freezing. The water in the air condenses on the coil and is drained. A second heat exchange coil reheats the air, that your dehumidifier exhausts in to the room.
A heat pump dehumidifier dumps heat lost from the compressor and fan motors into the air. It returns to the indoor air heat generated by the dehumidifier turning water vapour to liquid.
Chemical adsorbent dehumidifiers
This sort of dehumidifier is made for hot, humid climates and is not really suited for used in Canada.
Chemical adsorbent dehumidifiers absorb moisture from the air with a "desiccant"--a drying agent such as for example silica gel. Click here is on a heat exchange wheel. A separate air loop dries the wheel and exhausts the hot, damp air outdoors through special ducting.
A chemical adsorbent dehumidifier uses more energy when compared to a heat pump dehumidifier. It really is only cost-effective when it uses natural gas for heat exchange--and then only if natural gas can be acquired at a minimal summer rate.
Homemade dehumidifier
Some inventive people use bags of road de-icing salt to soak up moisture from the air. The wet salt solution drips right into a pan or floor drain, drying the air. As the salt runs off with the water removed from the air, it should be replaced. The system does not have any moving parts.
If you try this homemade dehumidifier, remember that salt is highly corrosive to metals and quite hard on your skin.
Dehumidifying ventilators
This type of dehumidifier includes a sensor-controller and exhaust fan. You set the sensor-controller to run when humidity reaches a set level. A dehumidifying ventilator is specially effective if the humidity source is in your basement.
Dehumidifying ventilators don't recover heat but they use less electricity than heat pump dehumidifiers. They are not effective in hot, muggy weather, as they bring more outside air into the house. They are often effective in cold weather.
A dehumidifying ventilator depressurizes your basement, which can cause combustion gas spillage. Make sure your heating contractor checks the venting for the gas furnace, water heater and wood-burning appliances. Contemplate using a carbon monoxide warning device if you install a dehumidifying ventilator.
Choosing a Dehumidifier
Dehumidifier purchase costs
Heat pump dehumidifiers are complex, low-production machines and are not low-cost items. Spring is apparently the best time to get: within the last few years dealers have held sales early in the spring with savings of $50 to $100.
The more water a dehumidifier holds --which is measured in litres or U.S. pints a day--the more it costs. You pay more for special features.
In 2000, you will probably pay between $200 and $250 for a unit rated at 10 L (21 U.S. pints or 2.1 imperial gal.) a day--suitable for a small home with a moderate moisture problem. The price rises to between $250 and $350 for a unit with a capacity of 20 L (42 U.S. pints or 4.3 imperial gal.) a day--suitable for a big house with more severe problems.
Running charges for both units are a comparable should they both have the same Efficiency Factor. Another section explains the Efficiency Factor.
Don't try to cut costs by investing in a unit that will not have automatic defrost. In case a room is too cool, a dehumidifier can frost over and stop removing moisture. A frosted-over dehumidifier left running for a long time will break down.
Get a unit with a two-speed fan. They're quieter at lower humidity, which reduces the nuisance factor. Test all units in the store for noise level, especially if you plan to use one in or near a bedroom.