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' Fixit-Moisture Problems Page 5 of 6 Due to better building practices,better building materials, upgrades in the building code, and homeowner's weatherization efforts,houses over the past ten years have become "tighter." While this has made the newer homes much more energy efficient, it has also led to moisture problems in homes lacking necessary mechanical ventilation. Here are two options for adding mechanical ventilation: � One: Install a quiet two-speed fan in the attic that will exhaust 100 to 150 cubic feet per minute. The fan should be controlled by a timer to run at low speed whenever the house is occupied, and to automatically switch to high speed during the more active times in your household. The fan should pull air . through sealed ductwork from the bath and kitchen, excluding the range hood exhaust system. The cost for an exhaust-only ventilation system ranges from $500 to $1,000. If you have a fuel-fired water heater or a fireplace,take precautions to prevent back drafting of combustion products by providing a combustion air inlet for both appliances, a booster fan on the water heater, and tight-fitting doors for the fireplace. Two: Install a heat recovery ventilator(HRV), also called an air-to-air heat exchanger. Since these units require routine filter cleaning, they should be � located in the basement. This will require installing some ductwork throughout the house,which adds extra expense in a finished home. The HRV should also have a quiet two-speed fan,but since it recovers heat all the time,the fan is often run continuously at low speed. These systems cost about$1,000 to $2,000. Since an HRV is a "balanced" system, backdrafting of your fuel-fired appliances should not be much of a concern. Adding mechanical ventilation should greatly reduce your moisture problem and improve your indoor air quality. At very cold temperatures, however, you can still expect some condensation on your windows, since it is difficult to keep the surface of the glass warm. Having better performing "low-e" windows, an airtight inner storm window, or shrink-wrap plastic applied on your windows will help, but will not replace the benefits of ventilation. Recommended publications: I l:�m� \f�,i��u,�c. ��`indc,��s nnd �)c��; Back to beginning of or_______ _ . Bathroom moisture How can you determine if a bathroom needs venting for moisture?•A family member has a large Victorian type house built in 1900. It has a boiler/radiator type heating and the house tends to be dry in the winter. Recently a shower was installed in the bathroom, which, of course,produces moisture. As soon as the bathroom door is opened the moisture in the air clears, but a layer of ice coats the window. If left undisturbed, the moisture from the window dissipates eventually. We do not want the window frame to rot, but do not know if it is wise to install a vent with fan. Could that produce other problems? Would just wiping the window with a towel be sufficient? What would be the best solution? Since your moisture problems occur in only one room and are primarily http://www.commerce.state.mn.us/pages/Energy/InfoCenter/FixIt/fixit04.htm 2/16/O1