Abstract:
A whole building ventilation system mixing box that mixes exterior air with air from within the building, having one or more exterior air inputs, on or more interior air inputs with one or more mixed air outputs that re-circulates the mixed air to a whole building HVAC system having one or more ventilation fans. The whole building ventilation system mixing box being open to circulation and mixes the return air from the interior air input with the exterior air whether or not the exhaust fan is on so as to equalize pressure between the interior and exterior of the building. In addition a method of sizing a whole building ventilation system mixer box for mixing exterior air from outside the building with interior air from within a building is provided and includes the steps of determining a value one or more variables related to a building or the air around the building then constructing a whole building mixer box with an at least one damper therein that allows operation without the concomitant operation of an intake fan so as to equalize air pressure within the building to ambient outside pressure, then coupling, adjusting, operating the HVAC device to move air and drawing in cooled or heated air and equalizing the air pressure in the building with the addition of exterior air.

Description:
FIELD OF THE INVENTION  
       [0001]    The invention relates to a whole building or home air ventilation/pressure equalization system air mixer with dampers having a first fresh air intake of an at least two intakes as part of the whole building ventilation system, where fresh air is taken into the system via the first intake of the at least two intakes from outside atmosphere and is mixed in an air box with air from a second of an at least two intakes providing air treated by the air handling system, for instance heated air from a furnace or cooled air from an air conditioner. 
       BACKGROUND OF THE INVENTION 
       [0002]    The invention relates to a whole building air ventilation and pressure equalization system. All buildings need ventilation to remove stale interior air and excessive moisture and to provide oxygen for the inhabitants. There has been considerable concern recently about how much ventilation is required to maintain the quality of air in homes. 
         [0003]    As the tolerances in the constructions of buildings has improved, resulting newer constructions are tightly built to save energy, but this can often times have a negative impact on the home without proper ventilation. Air within these “tight” buildings can be up to 10 times more polluted than the air outside. Microbial pollutants like mold, pet dander and plant pollen along with chemicals such as radon and volatile organic compounds (VOCs) create a toxic environment. The build-up of pollutants such as these is shown to lead to allergies, asthma and other health concerns. Research studies have also recently show that standard houses, those less “tightly” constructed, are just as likely to have indoor air quality problems as the newer energy efficient ones. While opening and closing windows offers one way to control outside air for ventilation, this strategy is rarely useful on a regular, year-round basis. Though obviously, the solution of building leaky buildings or maintaining leaky buildings or leaving open windows is not an answer. 
         [0004]    Regardless of the state of the construction, most building researchers believe that no building is so leaky that the occupants can be relieved of concerns about indoor air quality and therefore the air turnover is an issue. The researchers recommend mechanical ventilation systems for all buildings to accomplish the turnover of air or more accurately the ventilation of interior air into the atmosphere and the equalization of the pressures produced by such circulation. 
         [0005]    Ideally the amount of ventilation required depends on the number of occupants and their lifestyle, as well as the design and size of the home. The ANSI/ASHRAE standard, “Ventilation and Acceptable Indoor Air Quality in Low-Rise Residential Buildings” recommends guidelines that buildings have 7.5 natural cubic feet per minute of fresh air per bedroom, plus additional air flow equal to (in cubic feet per minute) 1% of the buildings conditioned area measured in square feet. In addition, the standard requires exhaust fans in the kitchen and bathrooms that can be operated when needed. 
         [0006]    Older, drafty buildings can have natural air leakage of 1.0 to 2.5 ACHnat. Standard homes built today are tighter and usually have rates of from 0.35 to 0.75 ACHnat. New, energy efficient homes have rates of 0.30 ACHnat or less. The problem is that air leaks are not a reliable source of fresh air and are not controllable. Air leaks are unpredictable, and leakage rates for all buildings vary. For example, air leakage is greater during cold, windy periods and can be quite low during hot weather where the air is more still. Thus, indoor air pollutants may accumulate during periods of calm weather even in drafty buildings. These homes will also have many days when excessive infiltration provides too much ventilation, causing discomfort, high energy bills, and possible deterioration of the building envelope. 
         [0007]    Concerns about indoor air quality are leading more and more homeowners to install controlled ventilation systems to provide a reliable source of fresh air. The most basic of these is the direct exhaust vent in kitchens and bathrooms. Nearly all these exhaust fans are ineffective to ventilate a building with “fresh” air, add to pressure differential problems, and are a prime contributor to interior moisture problems in homes. To combat the issue of poor ventilation, many studies from Building Science organizations, government and independent building science experts indicate that homes need whole building ventilation throughout the day to maintain a healthy indoor environment. Whole building ventilation systems usually have large single fans located in the attic or basement. Ductwork extends to rooms requiring ventilation. The air vented from the home by exhaust fans must be replaced by outside air. This “new” or “fresh” air comes into the home either through air leakage or through a controlled inlet. 
         [0008]    Relying on air leaks requires no extra equipment; however, the occupant has little control over the air entry points. Many of the air leaks come from undesirable locations, such as crawl spaces or attics. If the home is airtight, the ventilation fans will not be able to pull in enough outside air to balance the air being exhausted. This pressure differential also adds to the operating load of appliances in the building and can add to drafts in unwanted locations. Providing fresh outside air through inlet vents is a preferable option. 
         [0009]    Outside air can thus also be drawn into and distributed through the home via the ducts for the forced-air heating and cooling system. The blower for the ventilation system is either the air handler for the heating and cooling system or a smaller unit that is strictly designed to provide ventilation air. A slight disadvantage of using the HVAC blower is that incoming ventilation air may have sufficient velocity to affect comfort during cold weather. 
         [0010]    Typically with the existing systems on the market the systems are incorporated in the return ductwork via a small outside air duct that may have a damper which opens when the ventilation fan operates. This however results in a more costly system to operate and one that may or may not be properly balanced to address the pressure issue created by the exhaust from ancillary fans or meet the target fresh air turnover requirements as noted above. These systems also require powered dampers and do not operate continuously, requiring timers or sensors again increasing costs and complexity of the system. 
         [0011]    As noted herein, these existing systems can also result in damage to existing HVAC systems due to inadequate pre-mix of the incoming air and a lack of balancing within the building. The temperature extremes that may exist as between outside air and the interior operating temperatures of a furnace during winter. Similarly, the imbalance created over a prolonged period where the system was not actively engaged, e.g. when the furnace is off, the system may cause a significant pressure imbalance, resulting in increased pressures on the fan moving the air in the building. In each instance, the operational life of the HVAC equipment may be compromised. Similarly, the on again off again pressure differential may result in issues and damage to appliances in the building, for instance stoves and similar appliances that have exhausts. 
         [0012]    There exists a need to provide a means for meeting fresh air inlet requirements with a system that is functioning to provide pressure balancing and air circulation continuously, with or without the air handling fan being on, while also providing a variable and controllable inlet of fresh air and, due to the continuous operation, reduce loading on the air handling equipment and appliances and thereby improve the useful life of the equipment. Such a system would be designed to be more energy efficient than existing systems and will not cause damage to the furnace or AC unit, as other designs can, by being continuously open and utilizing a properly sized air intake mixing box or plenum with intake ducts from the furnace/AC or air handler unit and fresh outside air, mixing the air and sending it through the outgoing duct to the treated air in the return and back into the furnace/AC unit and allowing for it to be distributed throughout the whole building. 
         [0013]    There exists a need to reduce the pressure and temperature gradient within the system as between incoming external air and internal air while maintaining the air flow and balancing pressure to meet appliance and exhaust fan needs, regulate the amount of infiltration points and air, and avoid contaminated air from being forced into the building. 
       SUMMARY OF THE INVENTION 
       [0014]    An object of the invention is to provide a more efficient, passive whole building air circulation inlet and pressurization system which requires little or no electricity to operate and which in part reduces pressure imbalances, improves in home air quality, and improves efficiency in existing equipment and appliances. 
         [0015]    A still further object of the invention is to provide a system where the air handling fan does not need to be in operation to work, the system works when the furnace or HVAC is passive to continue to equalize pressure and allow for mixing of exterior air into the home. 
         [0016]    A further object of the invention is to provide a system which operates with an open duct intake, where exemplary embodiments utilize between about 100% of the opening width and about 25% of the open width of the intake seasonally. 
         [0017]    A still further aspect of the invention is to balance the air pressure in the building at all times, bringing in fresh air as needed, not only when motor or furnace is on and because of this will permit all other appliances will operate more efficiently. 
         [0018]    Yet another object of the invention is to provide a system that is more energy efficient and will not cause damage to the furnace or AC unit, as other design can, by providing adequate mixing in a mixing box or plenum prior to the return of the air to the Furnace or HVAC. 
         [0019]    Another object of the invention is to provide an application specific size mixing box or plenum based on variables which can include square footage of the building and the appliances installed, where the calculation is used to determine the minimum size of the box and the ratio and the size of the duct work connecting the system is determined by the size of the box. 
         [0020]    The invention includes an apparatus, a method for sizing the instant invention, a system and a method for using the apparatus. 
         [0021]    The apparatus of the invention includes a whole building ventilation system mixing box mixing exterior air with air from within the building, having an at least one exterior air input; an at least one interior air input; an at least one mixed air output that re-circulates the mixed air to a whole building HVAC system having an at least one ventilation fan. Where the whole building ventilation system mixing box is open to circulation and mixes the return air from the at least one interior air input with the exterior air whether or not the exhaust fan is on so as to equalize pressure between the interior and exterior of the building. 
         [0022]    The whole building ventilation system of claim having a further an at least one damper, wherein the amount of air admitted by the exterior air input is adjusted based an at least on variable within the building. The at least one variable can be based on at least one of square footage, number of occupants, exhaust flow from non-HVAC sources, and special environmental needs for the building. 
         [0023]    The at least one damper can be set to be at least partially opened during normal operation at all times. The at least one damper can be set to be substantially open during normal operation. The whole building ventilation system further having an at least one deflector to promote mixing of the air from the at least one interior input with the air from the at least one exterior input before moving the air through the outlet to the HVAC system. 
         [0024]    The at least one exterior input is a single exterior input can be a single input and the at least one interior input can be single interior input. The at least one exterior air input, the at least one interior air input and the at least one air output can have, but are not limited to, a diameter of between about 2 inches and about 12 inches. More specifically, the at least one exterior air input, has a diameter of between about 6 inches and about 7 inches. More specifically, the at least one interior air input can have a diameter of between about 4 inches and about 5 inches; the at least one air output have a diameter of between 7 inches and 8 inches. 
         [0025]    The method of the invention includes a method of sizing a whole building ventilation system mixer box for mixing exterior air from outside the building with interior air from within a building, providing the steps of determining a value for an at least one variable related to a building or the air around the building; constructing a whole building mixer box comprising at least one outside air input, at least one inside air input, and an outlet returning air to the building with an at least one damper therein that allows operation without the concomitant operation of an intake fan so as to equalize air pressure within the building to ambient outside pressure; coupling said mixer box to an HVAC device that is further coupled to an air vent system for the whole building; adjusting an inlet of the mixer box with a damper to vary the volume admitted through to the mixer box; operating the HVAC device to move air; and drawing in cooled or heated air and equalizing the air pressure in the building with the addition of exterior air. 
         [0026]    The step of determining a value for an at least one variable can further include determining a value based on at least one square footage, number of occupants, exhaust flow from non-HVAC sources, and special environmental needs such as electronics within the building. 
         [0027]    The step of constructing a whole building mixer box further comprises constructing a box having the at least one outside air input, the at least one inside air input, the outlet returning air to the building can have diameters of between about 2 inches and about 12 inches based on the determined value for the at least one variable related to the building. The at least one exterior air input can have a diameter of between about 6 inches and about 7 inches and the at least one interior air input has a diameter of between about 4 inches and about 5 inches and the at least one air output has a diameter of between 7 inches and 8 inches, based on the calculation of the variables. 
         [0028]    Moreover, the above objects and advantages of the invention are illustrative, and not exhaustive, of those which can be achieved by the invention. Thus, these and other objects and advantages of the invention will be apparent from the description herein, both as embodied herein and as modified in view of any variations which will be apparent to those skilled in the art. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0029]    Embodiments of the invention are explained in greater detail by way of the drawings, where the same reference numerals refer to the same features. 
           [0030]      FIG. 1  shows a plan view of the whole building ventilation system of the prior art. 
           [0031]      FIG. 2  shows a plan view of the whole building ventilation system of the instant invention. 
           [0032]      FIGS. 3A ,  3 B,  3 C and  4  show side views and a cross sectional view of the air flow mixer of the instant invention respectively. 
           [0033]      FIG. 5  shows a cross sectional view of a further embodiment of the air flow mixer of the instant invention having a fire safety damper. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0034]    The instant invention is directed to an apparatus, method and product of manufacture that provides for fresh air ventilation and pressure equalization in a whole building ventilation system having a mixing box or chamber with at least one damper provided on an at least one of the at least one intakes to moderate and/or selectively cease flow into the device. Such dampers would assist in selectively adjusting the volume of the atmospheric air admitted and preventing excessive loss of treated air to the atmosphere when not mixing the treated air. This improves the efficiency of the unit. Additionally a “seal locking” version can lock an airtight seal in place in cases of fires or sensor inputs to prevent fresh air from aiding in fueling a building fire. 
         [0035]      FIG. 1  shows a prior art home ventilation system. An inlet  5  is provided from the exterior of the building, in this instance from a through wall inlet. A conduit  13  provides a line for incoming airflow which passes an electronically controlled valve  11 ,  12 . A return air duct  14  is coupled to a furnace  16 . The return air duct  14  is installed in such a manner that it conducts the flow of relatively cool air from the space being heated back to a furnace  16  by way of an air filter  17 . A blower  18  in the furnace  16  acts to draw into the furnace the return air from the return air duct  14 , as well as outside air through the outside air duct  13 . The air mixture is then heated by the furnace  16  and delivered to the spaced to be heated by way of the hot air duct  19 . 
         [0036]    As noted, such systems do introduce outside air into the system is to ensure that the quality of the air in the structure is maintained such that it does not become stagnant. However, the prior art device operates such that whenever the furnace blower  18  is on, the damper  12  is opened by the furnace or thermostat control. When the blower  18  is off, the damper  12  would be either shut or at rest at a minimum open position. There is no buffering of the airflow, there is no mixing or pre-mixing of what could be very cold air being driven to the furnace. This significantly increases the workload for the furnace  16 . Additionally, the prior art does not account for other pressure imbalancing aspects in the house or building. As noted, these can include exhaust fans, chimney flues, and the like and when in the shut position, though the temperature internally may remain constant, no fresh air is admitted, exacerbating problems with unwanted infiltration sites in drafty structures and causing a negative pressure inside the building in the case of tightly sealed structures. 
         [0037]      FIG. 2  shows a plan view of an exemplary embodiment of the instant invention. The instant invention is directed to a whole building ventilation system mixer and damper system that allows for the draw of air from the environment and the mixing of this air with interior air that is heated or cooled by conventional HVAC systems regardless of the state of the fan. An inlet  50  similar to that of  FIG. 1  is provided. This is coupled to an input branch  60 . This ends in an inlet  110 . The mixer or plenum  100  has an at least one environmental air supply inlet  110  which is coupled to the vent or inlet or louver or similar opening  50  to the exterior or environmental air. This exterior air  70  is drawn in by the pressure difference created between the exterior and interior of the building through ventilation line or input branch  60 . In the case of a typical home, as noted above, a pressure difference is created by things like exhaust fans in the home and temperature variances. Additionally, active circulation in the HVAC system also gives rise to a pressure differential. The mixer  100  of the instant invention functions to balance that pressure differential as well regardless of the state of the HVAC system. 
         [0038]    A further at least one interior or treated air inlet  130  is provided and coupled to an at least one return air duct or conduit or return  210 . The return air duct  210  is coupled to a home building ventilation system and carries treated air, typically air being returned from use in the building in the return air flow  90 , as better seen in  FIGS. 3A-C  and  4 . A further outlet  120  is provided so that the treated air is mixed in the plenum or mixing box  100  and returned into the air handling equipment for recirculation along a mixed air return conduit or duct or branch  220  as mixed air  80 . A filter  230  is provided to filter the mixed air  80 . The mixed air  80  is moved across or through a cooling or heating HVAC unit  240  by the main fan  250 . 
         [0039]    A damper  300  is provided that can be manually adjusted at the inlet  110 . The damper  300  in the exemplary embodiment shown as, but is certainly not limited to, an iris or radial sliding blade damper. As more clearly seen in  FIG. 3B , the damper can be adjusted to occlude a portion of the inlet and adjust flow. This can be done manually in the exemplary embodiment. The adjustment can be made for instance to further refine airflow in the system and tailor it to the building. These refinements can be made to accommodate variables specific to the building, such as, but certainly not limited to, variations at least one of the square footage, number of occupants, exhaust flow from non-HVAC sources, and special environmental needs such as large amounts of electronics within the building. Further variables can be accommodate based on the specific building and are embraced by the spirit of the invention. It can also be done to accommodate seasonal changes and needs. The inlet remains at least in part open at all times. The damper  300  may also be modified to provide fire safety and suppression in a further embodiment, as discussed below in relation to  FIGS. 5 . 
         [0040]      FIGS. 3A ,  3 B,  3 C, and  4  show a front, a back, a side and a cross section view of the exemplary embodiment of the instant invention shown in  FIG. 2 . The incoming exterior air  70  is brought in through the inlet  110  into the mixing box  100 . Damper  300  is provided, as best seen in  FIGS. 3B and 4 , so as to adjust the amount of airflow being admitted. The incoming return air  90  is brought into the mixing box. A deflector  160  is provided to deflect the return air and enhance mixing of the air  150  in the mixing box or plenum  100 . The mixed air  80  then exits via the outlet  120  to the ventilation system as described above. Further dampers (not shown) can also be provided on the incoming air return as well as the outlet. This occurs prior to the ventilation equipment and regardless of whether the principal fan in the HVAC  250  is in operation or not. That is the instant invention, unlike the prior art of  FIG. 1 , is in operation regardless of whether the main HVAC fan  250  creates the pressure differential which requires balancing. This is important, since as noted above, a number of other sources can provide circulation and pressure variances within the building. The instant invention takes advantage of these other sources to provide further fresh air to the building. Furthermore, the instant invention pre-mixes the air so as to reduce the stress on HVAC components that treat the air. That is the outside air  70  is warmed by return air  90  as mixed air or cooled by return air  90  as mixed air depending on the season. The size of the box may be varied based on calculations made which include variables for the building or building size, the number of appliances, the construction, the age of the building, and similar variables. 
         [0041]    Furthermore, the sizing of the mixing box or plenum  100  in an exemplary embodiment is designed for application specific use. That is the size and thereby volume of the mixing box  100  is determined by one or more building variables. These building variables can include, but are not limited to the square footage of the home, the number of exhaust points, the appliances in use, the number of inhabitants and the like. The method of sizing and installing the whole building ventilation system with the instant invention is thus managed by building variables which contribute to the overall size of the mixing box  100 . The size of the mixing box  100  based on these variables dictates the diameter and length of the inlet or input branch  60  from the inlet  50 , the diameter and length of the return branch or air duct  210 , and the diameter and length of the mixed air return branch  220 . 
         [0042]    The instant invention includes a method of sizing a whole building ventilator as well. Specifically, the inputs and outputs must be balanced to provide adequate flow to balance the pressures efficiently. As such, the invention includes a method of using variables from a building site to provide adequate inputs and outputs flow to balance the building. The size of the ducts is selected to correspond with one of several variables, which can include for example but is certainly not limited to square footage, number of occupants, exhaust flow from non-HVAC sources, special needs such as electronics, and other site specific variables related to the building, the occupants and the contents. 
         [0043]    Some non limiting examples of the results for calculation of inputs and outputs sizes for particular exemplary dimensions using the instant invention include, for example, but are certainly not limited to, calculations for a dwelling up to about 2600 sq. ft./air entry volume 427/cfm a fresh air duct or input of outside air input of about 4 inches to about 8 inches, particularly about 6 inches and a mixed air return duct or output from the unit of about between 6 inches and 12 inches, particularly about 7 inches and an interior air return duct or input to return air from the HVAC in the building of between about 2 inches and 6 inches, particularly about 4 inches taking into account four bedroom occupancy and a standard load of exhaust fans in the dwelling. Similarly for dwellings between up to about 3800 sq. ft and up to about 7000 sq. ft, the air entry volume can be but certainly is not limited to between about 500/cfm and about 1400/cfm, respectively. The corresponding ducts can be for example, but are certainly not limited to a fresh air or outside air duct or input diameter of about 4 inches to about 12 inches, particularly about 6 to 8 inches and a duct from the HVAC unit or a return duct or inside air input of about between 3 inches and 8 inches, particularly about 4 to 6 inches and a duct to return or an outlet or an exit duct of between about 2 inches and 12 inches, particularly about 4 to 10 inches. 
         [0044]      FIG. 5  shows a cross-sectional view of a further embodiment of the air flow mixer of the instant invention having a fire safety damper. The embodiment is very similar to that of  FIGS. 3A-4 . The incoming exterior air  70  is brought in through the inlet  110  into the mixing box  100 . The incoming return air  90  is brought into the mixing box. A deflector  160  is provided to deflect the return air and enhance mixing of the air  150  in the mixing box or plenum  100 . The mixed air  80  then exits via the outlet  120  to the ventilation system as described above. This occurs prior to the ventilation equipment and regardless of whether the principal fan in the HVAC  250  is in operation or not. That is the instant invention, unlike the prior art of  FIG. 1 , is in operation regardless of whether the main HVAC fan  250  creates the pressure differential which requires balancing. This is important, since as noted above, a number of other sources can provide circulation and pressure variances within the building. The instant invention takes advantage of these other sources to provide further fresh air to the building. Furthermore, the instant invention pre-mixes the air so as to reduce the stress on HVAC components that treat the air. That is the outside air  70  is warmed by return air as mixed air or cooled by return air as mixed air depending on the season. The size of the box may be varied based on calculations made which include variables for the house or building size, the number of appliances, the construction, the age of the building, and similar variables. 
         [0045]    Additionally, as indicated in the exemplary embodiment shown above, an at least one damper is provided. Here, the at least one damper  300  is supplemented by a further damper  310  that is provided at or near the exterior air intake  110 . The at least one damper  300  allows for the volume of exterior air  70  to be varied for the season and the further damper  310  allows for the air to be shut off completely in a fire emergency. The damper  300  again may be a simple mechanical device that is manually adjusted. In the further exemplary embodiments the further damper  310  may incorporate a more complex spring system and include a sensor or other activator to register heat or other variables for identifying a fire emergency. The sensor  315  can be, but is not limited to, a heat responsive material that has a melting point that would correspond with incoming air at higher than advisable temperatures. The sensor  315  would activate from exposure to the heated air. In this instance, the sensor  315  would melt and release a lanyard or coupling with an at least one spring member  317  which moves an at least one coupling member  320  snapping the further damper  310  into a shut position to prevent air being drawn in to feed the fire. Similarly, an electronic sensor or thermocouple could be used with a small servo motor to release the springs or to automatically close the further damper  310 . 
         [0046]    The embodiments and examples discussed herein are non-limiting examples. The invention is described in detail with respect to preferred embodiments, and it will now be apparent from the foregoing to those skilled in the art that changes and modifications may be made without departing from the invention in its broader aspects, and the invention, therefore, as defined in the claims is intended to cover all such changes and modifications as fall within the true spirit of the invention.