Removing Moisture - June 24th 2008
Q: I am having a problem convincing my tenants to leave their bathroom exhaust fan on long enough after they bath or shower. Moisture is accumulating on the windows and there are signs of water drips on walls as well as some paint peeling in the bathroom window sill. They have said that the fans are too noisy to keep running. What can I do to ensure the fan is venting until the moisture is totally removed?
A: Bathroom ventilation is very important in protecting your bathroom against problems caused by too much moisture such as peeling paint and mold forming. To ensure the correct operation of an exhaust fan, remove the single pole toggle switch and replace with an electronic de-humidistat which will enable you to set the required relative humidity level and will automatically turn the fan on if the humidity level is over the humidity setting. For example: For outside temperatures over 0 Degrees Celsius the de-humidistat should be set at 40% relative humidity, For -12 to -18 Degrees Celsius the setting would be 35% and in the summer months you would set at 50% relative humidity.
Consider replacing the fan with a quieter and more efficient one. Chances are the quieter the fan the more it will get used. Two things to consider when choosing a new fan are the CFM and Sone levels. Sound levels are measured by an industry standard called a "Sone." The lower the sone, the quieter the fan. The best fans have sound ratings of 1.0 Sone or less. Units that produce more than 4 Sones or more should be avoided. However, the price goes up as the noise levels go down. For a fan to be effective at removing humidity it needs to be able to move a sufficient amount of air. To choose the proper unit for your bathroom, the rough guide of airflow is one CFM (cubic foot per minute) per square foot for bathrooms of one hundred square feet or smaller. For example, with a sixty square foot bath, you'll want a fan with a rating of 60 CFM or more.