Patent Application
20080182503
The present invention relates generally to the field of crawlspace drying systems for homes and more specifically to a crawlspace system that employs negative air pressure.
There is one consistent problem with almost all crawlspaces, too much moisture, which can cause significant amounts of mold and wood rot. To make matters worse, the results of air sampling show that the same molds in the crawlspace of a home are also found in the interior of the home. When the humidity in a crawlspace rises above 60% relative humidity (RH), conditions are favorable to saturate wood and cause mold to grow. When the moisture content of wood reaches above 16% moisture content (MC) conditions are favorable for mold to grow. When the moisture content of wood elevates between 28% and 35%, wood rot will occur. In the summer time throughout much of the country, the crawlspace moisture content is between 22% and 38% MC. The climate in much of the country during the summer months cause the humidity to be sustained above 60% RH. This moist, stagnant air gets trapped inside of crawlspaces causing favorable conditions for mold growth and wood rot. Further, many times owners of these homes will go to their doctor with an unexplained sickness that they cannot overcome. Today technology has progressed in the medical field to the point that doctors are able to diagnose when patients are sick from mold and mold spores. In the majority of cases, there is no visible mold in the home, until the crawlspace is inspected. In all of these cases, extensive testing has shown that the same molds that are present in the crawlspace are also present inside of the living area of the home. This occurs for two reasons, homes are not built airtight, and all crawlspaces are under positive pressure, meaning that outside air flows into the crawlspace and then filters into the living area of the home. When air from the crawlspace filters into the home, mold spores are carried with the air. The contaminated air is pushed into the home through openings in the floor such as, plumbing holes, wiring holes, and seams in flooring.
A typical crawlspace has over 50,000 mold spores per cubic meter of air. Safe levels for breathable air are well below 1000 mold spores per cubic meter of air. Depending on the type of mold, even levels below 1000 mold spores per cubic meter of air can be harmful. Generally speaking, the molds that grow from saturated wood are harmful, and they include stachybotryis, and aspergillus/penicillium. To properly remediate a crawlspace with moderate mold damage is very labor intensive and costly, typically $15,000.00 to $20,000.00 to remediate a crawlspace on a 2400 SF home. Once the remediation is complete, a drying system must still be installed or the crawlspace will need to be remediated again within two years. Homeowners and restoration companies have recently made lawmakers aware of this problem and some states have implemented codes that require a crawlspace ventilation system in all new homes.
According to the EPA, “the most effective way to improve indoor air quality is to eliminate or control sources of pollution, or to reduce their emissions. Another important approach that goes hand in hand with controlling pollution is using mechanical ventilation to lower the concentrations of pollutants in your home by increasing the amount of outdoor air coming inside. Good ventilation is important because it protects both your health and your home. Good ventilation protects you and your family from unpleasant odors, irritating pollutants, and potentially dangerous gases. Well-planned ventilation also helps prevent the growth of mold and mildew, which can cause allergic reactions and aggravate lung diseases such as asthma. Too much moisture in a home can lead to mold, mildew, and other biological growth. This in turn can lead to a variety of health effects ranging from more common allergic reactions, asthma attacks, and hypersensitivity pneumonitis, to death. Excess moisture can be in the form of high relative humidity, leaks in the roof, walls, or plumbing, air moving from the inside or the outside into the walls, or from the basement or crawlspace. Methods to control moisture include fixing any water leaks; providing ventilation in the home; air-sealing; properly using vapor barriers in wall construction, roofs; and preventing soil moisture from entering the home through basements and crawlspaces.”
The Institute of Inspection Cleaning and Restoration states, “Even high humidity or warm moist air condensing on cool surfaces can trigger mold problems. Create negative pressure to prevent mold from spreading.”
Advance Energy addresses the mold problem as follows: “These symptoms are most often noticed in the humid spring and summer seasons but can occur at any time of the year. Often, the heating and air conditioning contractor is the first person the residents call to deal with the problem. Typically though, the problem is not due to a failure of the air conditioning system; it results from poor moisture control in the crawl space.”
For many decades, building codes and conventional wisdom have prescribed ventilation with outside air as the primary method of moisture control in crawl spaces. In the humid Southeast, however, ventilation with outside air only makes moisture problems worse. Recent research by Advanced Energy and others indicates that a new type of crawl space system, with NO vents to the outside, can provide greatly improved moisture control and significant energy savings when properly installed. Unfortunately, there is no cost effective system currently available to deal with this problem. What is currently available in the industry is a mix of high priced equipment that comes with an even higher maintenance price. Crawlspace dehumidifiers are expensive, one 60 pint crawlspace dehumidifier, capable of dehumidifying about 5,000 cubic ft of air, cost approximately $3,000.00 to install. Crawlspace dehumidifiers have many problems. The sealing process of the crawlspace must be very precise, meaning very time consuming. Any crack or hole in the crawlspace after the sealing process allows outside air in, and results in the dehumidifier trying to dry an endless supply of humid air, which of course, it cannot. Further, a dehumidifier will only reduce the humidity 15 to 20 percent and they do not work properly in temperatures above 90° Fahrenheit. If the outside humidity is over 80% RH, crawlspace dehumidifiers are ineffective at reducing the humidity to a safe level. Moreover, reducing the humidity in the air will not dry previously moist wood and insulation. High static airflow is needed to pull the moisture out that has wicked into materials such as wood and insulation. When high airflow moves over the surface of a porous material, it creates pressure or a draft and pulls the moisture out of the material. Wood is not very porous therefore is absorbs moisture slowly and also evaporates moisture slowly making it even more difficult to dry. To make matters worse, the exhaust of a dehumidifier will create more positive pressure in a crawlspace enabling more contaminated air to enter the living space of the home. Each dehumidifier runs on about 9 to 13 Amps and generates heat, meaning they are not very cost effective in energy consumption. Dehumidifiers also have a high break down rate because of the conditions in which they operate.
A more involved crawlspace drying system is a sealing and dehumidifying process that involves covering over the foundation walls with a heavy duty plastic material and installing a dehumidifier. The cost can be between $8,000 and $20,000. This system requires that the mold in the crawlspace be remediated before installation. The cost for mold remediation can be between $8,000.00 and $25,000. In addition, because of the construction of a crawlspace (the tight working area, ducting and wiring that covers up portions of moldy wood) it is very difficult and near impossible to fully remediate a crawlspace of mold. Moreover, the heat and positive pressure generated by the dehumidifier creates a bad environment under the home. The crawlspace air is forced into the home and creates an unsound environment and additional heat inside of the home. Any spores, dust, dirt particles and other particulate in a crawlspace environment will also be forced into the living area.
Another prior system involves hanging twenty to twenty-five 150 CFM fans from the rafters of the crawlspace. There is no price range of this system due to the fact it is not on the market however, due to the amount of hardware involved the price is expected to be high, along with the energy consumption. The problems with this system include, the system is untested and hot damp air is brought into the crawlspace from the outside. Further, the system's low CFM air movement will not have the capability to pull moisture out of wood.
There is another system that pulls air from the attic and sends it down into the crawlspace. Problems of this system include the following: the fan blowing into the crawlspace creates positive pressure in the crawlspace; there is not enough air movement to pull moisture out of wood; attic air is very hot and humid, typical relative humidity is around 20% higher than that outside; and, hot air forced under the home rises and enters the home along with contaminated air.
Yet another system involves installing larger foundation vents, fans and exhaust fans. The cost for an average home is around $2,000 to $5,000. Problems with this system include the crawlspaces may remain under positive pressure, hot humid outside air is brought into the crawlspace, and on rainy and humid days moisture content will actually increase in the crawlspace. Further, the equipment is visible from the outside and must be installed into the foundation, which involves cutting through brick and/or solid block.
What is needed in the field is a cost effective crawlspace system that dries the crawlspace and prevents contaminated, moldy air in the crawlspace from moving into the home. The ideal system would create high enough air movements that will pull out moisture that has wicked into wood and insulation. The ideal system would also create negative air in the crawlspace thereby eliminating harmful contaminated air from entering the home and creating healthy air exchanges in the living area of the home with fresh air from the outside.
A system for drying the crawlspace of a home and for reducing the mold level in the crawlspace and in the living area of the home. The system creates a negative pressure in the crawlspace that generates beneficial air exchanges in the living area of the home. The system comprises, multiple vent covers, at least one floor register, multiple air movers, and at least on exhaust fan. The vent covers are designed to fit over and seal the existing vents of the crawlspace, so that outside air can no longer freely flow into the crawlspace. The floor register provides controlled airflow from the living area of the home into the crawlspace. The floor register includes an upper portion that at least partially extends into the living area and a lower portion that extends into the crawlspace. The lower portion includes a one-way airflow valve that allows air to flow only into the crawlspace. The air movers are strategically placed around the crawlspace so that a circular airflow is created in the crawlspace. The exhaust fan pulls air from the crawlspace and exhausts the air to the outside. The exhaust fan/fans exhaust air from the crawlspace into the atmosphere thereby creating negative pressure in the crawlspace.
In the preferred embodiment: the floor register and the exhaust fan are located on opposite ends of the crawlspace; the floor register provides airflow from the living area to the crawlspace at a rate of 80-120 CFM; and, each vent cover comprises at least two layers, an outer layer made of a durable material and an inner layer made of an insulating material. Further, each air mover preferably comprises a 16-20 inch fan, and each exhaust fan comprises either two 6-10 inch fans or one 16-20 inch fan.
The present system is economically designed to operate on 10-13 Amps of power, depending on the size and number of fans. The optimum placement for the air movers in a rectangular crawlspace is to have an even distribution and position each air mover so that it has a 42 degree angle towards the wall, from a parallel, and a declination of 5 degrees toward the ground, from a parallel. These angles increase the speed of airflow in the crawlspace and provide for a greater distance of air travel. After the present system reduces the mold level in the crawlspace and in the living area of the home, the system is able to maintain the mold levels at a reduced and safe level. The present N.A.S. Crawl System eliminates two of the five items that mold needs in order to grow; moisture and a stagnate environment. The negative pressure created in the crawlspace by the system propagates to the living area of the home causing outside air to enter the living area, through cracks in doorways and window sills and other openings, thereby generating fresh air exchanges in the living area of the home.
It is an object of the present invention to provide an effective drying system for crawlspaces that uses air movers with a unique two-piece design.
It is another object of the present invention to reduce mold levels in the crawlspace and the living area of a home.
It is still another object of the present invention to change the airflow in a home, of from the crawlspace to the living area, to from the living area to the crawlspace.
It is still yet another object of the present invention to generate a negative air pressure in the crawlspace that subsequently cause healthy air exchanges with outside air, in the living area of the home.
The invention of the present application will now be described in more detail with reference to the accompanying drawings, given only by way of example, in which:
a) shows the airflow in traditional homes with a crawlspace;
b) shows the airflow in a home with the present system installed in the crawlspace;
a) & (b) show an exemplary two-part air mover.
a) shows the airflow in a traditional home 100 with a crawlspace 110. In the traditional home 100, air enters the crawlspace 110 through vents that are provided in the home for the crawlspace. The air becomes heated in the crawlspace, especially in summer months, and enters the living space 105 of the home through cracks, holes and other openings in the floor of the home. Air in the living space 105 of the home gets trapped inside the home and the same unhealthy air re-circulates within the home. Common HVAC filters are not designed to trap harmful particulate that is microscopic like mold. The airflow shown in
b) shows that the airflow is changed in the same home 100 after the present Negative Air Supplied (NAS) Crawlspace system has been installed in the crawlspace 115. The present system creates a negative pressure in the crawlspace 115, relative to the living area 105 of the home, which stops air in the crawlspace from moving into the living area 105 of the home. After the present system is installed, air moves out of the living area 105 of the home and into the crawlspace 115 of the home, and later is exhausted to the outside. The air movement created by the present system dries any standing water in the crawlspace 110, and also wicks moisture out of wood and other materials in the crawlspace 110 to create a moisture free environment, as far as mold is concerned. Mold needs a moisture content (MC) level that is above 16% in order to grow and survive. There are also four other essential elements that must be present in any crawlspace for mold to survive: food, the proper temperature, a stagnate environment, and time. Eliminate any one of the essential elements and mold is stopped. The present N.A.S. Crawl System eliminates two of these essential elements: moisture; and, a stagnate environment.
Closing and sealing the vents eliminates the main reason why crawlspaces retain moisture. The present vent covers keep out the majority of hot humid air, then the air movers of the present system cool and evaporate the remaining air. Air at a high velocity creates friction or a vapor pull on the surfaces it flows over. This pulls the moisture from the porous or semi porous materials in the crawlspace. Dehumidified air (80 to 120 CFM) enters the crawlspace through the floor register and helps cool and evaporate the moisture in the air. Cooler air lowers the GPP (grain per pound) grains of moisture in the air that aids in pulling the trapped moisture out of wood, insulation and other materials in the crawlspace. In addition the lower temperatures created in the crawlspace have a radiant effect on the home that helps keep the home cooler in the summer and helps in energy savings.
After moisture levels are reduced in the crawlspace, mold reduction occurs. High airflow provided by the NAS Crawlspace System pulls mold spores off of the hyphae or stems. Exhausting air sends the mold spores in the air to the outside atmosphere. Air exchanges bring in clean air that replaces the contaminated air. In addition the air in a home that contains mold, dust, pet dander, carbon dioxide, carbon monoxide and other harmful contaminates is also replaced with cleaner air from the outside. The present NAS Crawlspace System is designed to impede moisture intrusion, evaporate present moisture, dry floor joists, sub floors, and insulation, and reduce spore counts in the crawlspace and inside of the home. The present system utilizes multiple drying theories to create a drying chamber in the crawlspace. Air movement and negative air pressure lead to significant reduction in moisture levels, airborne particulate and mold spores. The NAS Crawlspace System is also designed for quick installation and is not labor intensive. This system is the only one of its kind that can guarantee dry conditions in a crawlspace, and reduced spore counts in the air of the crawlspace and in the interior of the home. The system also creates air exchanges inside of the home, as recommended by the EPA. The NAS Crawlspace System is completely hidden inside of the crawlspace. The air movers are specifically designed to operate in this environment. The entire system can operate on as little as 10 Amps of electrical power. The energy savings of a cooler home created by the system will offset the cost of running the system. It is an affordable and effective way to maintain safe moisture levels along with improving air quality. As
The negative air aspect of the present system is generated by the exhaust fans that are used to pull and exchange air from the crawlspace. The CFM of air exhausted out of the crawlspace creates the negative pressure in the crawlspace. The floor register allows the home to have a slight negative pressure that also allows the air in the living area to be exchanged with fresh air from outside. Air in a 2,400 SF home can be exchanged 7 to 8 times per day, with the present system.
a) shows the back of an exemplary vortex creating air mover 310 with novel two-piece housing, or shroud, 320 & 321. The upper half of the shroud 320 releasably engages with the lower half of the shroud 321 along engagement seams 328 & 329. Within the shroud 320 & 321, the fan housing 322 is supported, and held in a central location, by a rotate-able support bracket 323. The bottom connection points 324 & 325 of the support bracket 323 allow for the bracket, and the fan, to rotate when the top of the support bracket 323 is disconnected from the upper half of the shroud 320. The upper half of the shroud 320 includes connecting tabs 326 and 327 that releasably engage the top of the support bracket 323. The CFM for the air mover 310 is between 1460 and 2870, and the Amp draw is from 1.55 to 2.6, both depending upon the fan size and number of blades. The number of air movers used, and the size of the air movers, will depend upon the size of the crawlspace in which the present system is to be installed.
b) shows the assembled lower half of the air mover shown in
The present NAS Crawlspace System provides a cost-effective answer to the mold problem in many homes. The system's high-speed air movement provides efficient drying of all materials, yet the system operates on 10-13 Amps of power. Plus, the cooling effect provided by the evaporation reduces the home's air conditioning bill during summer months, which can offset the cost of running the system.
The foregoing description of the specific embodiments will so fully reveal the general nature of the invention that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept. For example, the present system could include an embodiment wherein two vortexes are created in the crawlspace of an irregularly shaped house. Therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology of terminology employed herein is for the purpose of description and not of limitation.
