Dehumidifiers work with 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 runs on the fan to draw indoor air over a heat exchange coil. The coil is nearly 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 into the room. A heat pump dehumidifier dumps heat lost from the compressor and fan motors into the air. It returns to the indoor air the 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 actually suited for use in Canada. Chemical adsorbent dehumidifiers absorb moisture from the air with a desiccant--a drying agent such as for example silica gel. Go to this site is on a heat exchange wheel. Another air loop dries the wheel and exhausts the hot, damp air outdoors through special ducting. A chemical adsorbent dehumidifier uses more energy than a heat pump dehumidifier. It really is only cost-effective when it uses 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. Because the salt runs off with the water taken off the air, it should be replaced. The system does not have any moving parts. If you try out this homemade dehumidifier, remember that salt is highly corrosive to metals and quite hard on your skin. Dehumidifying ventilators This kind of dehumidifier has a sensor-controller and exhaust fan. You set the sensor-controller to perform when humidity reaches a collection level. A dehumidifying ventilator is particularly 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 in to the house. They are often effective in winter. A dehumidifying ventilator depressurizes your basement, that may cause combustion gas spillage. Make sure your heating contractor checks the venting for the gas furnace, water heater and wood-burning appliances. Consider using a carbon monoxide warning device if you use a dehumidifying ventilator. Choosing a Dehumidifier Dehumidifier purchase costs Heat pump dehumidifiers are complex, low-production machines and are not low-cost items. Spring seems to be the best time to buy: in 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 can expect to 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 little house 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 large house with more serious problems. Running costs for both units are about the same 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. If a room is too cool, a dehumidifier can frost over and stop removing moisture. A frosted-over dehumidifier left running for some 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 utilize one in or near a bedroom.
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