| Dehumidifiers use a heat pump (similar to an air | | | | Dehumidifying ventilators don't recover heat but |
| conditioner's heat pump) or chemical adsorbents | | | | they use less electricity than heat pump |
| to remove moisture from the air without cooling | | | | dehumidifiers. They are not effective in hot, |
| the air. | | | | muggy weather, as they bring more outside air |
| A heat pump dehumidifier uses a fan to draw | | | | into the house. They can be effective in cold |
| indoor air over a heat exchange coil. The coil is | | | | weather. |
| almost freezing. The water in the air condenses | | | | A dehumidifying ventilator depressurizes your |
| on the coil and is drained. A second heat | | | | basement, which can cause combustion gas |
| exchange coil reheats the air, which the | | | | spillage. Make sure your heating contractor checks |
| dehumidifier exhausts into the room. | | | | the venting for your gas furnace, water heater |
| A heat pump dehumidifier dumps heat lost from | | | | and wood-burning appliances. Consider using a |
| the compressor and fan motors into the air. It | | | | carbon monoxide warning device if you install a |
| returns to the indoor air the heat generated by | | | | dehumidifying ventilator. |
| the dehumidifier turning water vapour to liquid. | | | | Choosing a Dehumidifier |
| Chemical adsorbent dehumidifiers | | | | Dehumidifier purchase costs |
| This type of dehumidifier is designed for hot, | | | | Heat pump dehumidifiers are complex, |
| humid climates and is not really suited for use in | | | | low-production machines and are not low-cost |
| Canada. | | | | items. Spring seems to be the best time to buy: |
| Chemical adsorbent dehumidifiers absorb moisture | | | | in the last few years dealers have held sales early |
| from the air with a "desiccant"--a drying agent | | | | in the spring with savings of $50 to $100. |
| such as silica gel. The desiccant is on a heat | | | | The more water a dehumidifier holds --which is |
| exchange wheel. A separate air loop dries the | | | | measured in litres or U.S. pints a day--the more it |
| wheel and exhausts the hot, damp air outdoors | | | | costs. You pay more for special features. |
| through special ducting. | | | | In 2000, you can expect to pay between $200 |
| A chemical adsorbent dehumidifier uses more | | | | and $250 for a unit rated at 10 L (21 U.S. pints or |
| energy than a heat pump dehumidifier. It is only | | | | 2.1 imperial gal.) a day--suitable for a small house |
| cost-effective when it uses natural gas for heat | | | | with a moderate moisture problem. The price |
| exchange--and then only if natural gas is available | | | | rises to between $250 and $350 for a unit with a |
| at a low summer rate. | | | | capacity of 20 L (42 U.S. pints or 4.3 imperial gal.) |
| Homemade dehumidifier | | | | a day--suitable for a large house with more |
| Some inventive people use bags of road de-icing | | | | severe problems. |
| salt to absorb moisture from the air. The wet salt | | | | Running costs for both units are about the same |
| solution drips into a pan or floor drain, drying the | | | | if they both have the same Efficiency Factor. The |
| air. Because the salt runs off with the water | | | | next section explains the Efficiency Factor. |
| removed from the air, it must be replaced. The | | | | Don't try to save money by buying a unit that |
| system has no moving parts. | | | | does not have automatic defrost. If a room is |
| If you try this homemade dehumidifier, | | | | too cool, a dehumidifier can frost over and stop |
| remember that salt is highly corrosive to metals | | | | removing moisture. A frosted-over dehumidifier |
| and quite hard on the skin. | | | | left running for a long time will break down. |
| Dehumidifying ventilators | | | | Get a unit with a two-speed fan. They are quieter |
| This type of dehumidifier has a sensor-controller | | | | at lower humidity, which reduces the nuisance |
| and exhaust fan. You set the sensor-controller to | | | | factor. Test all units in the store for noise level, |
| run when humidity reaches a set level. A | | | | especially if you plan to use one in or near a |
| dehumidifying ventilator is particularly effective if | | | | bedroom. |
| the humidity source is in your basement. | | | | |