Abstract:
An air circulation system is provided for a building having a plurality of zones to be heated, ventilated or cooled. The system includes an air circulating apparatus arranged to supply either heated, cooled or ventilated supply air to the various zones of the building via a plurality of supply ducts. The apparatus also draws return air from the zones via a plurality of return ducts. A damper is coupled to both the supply and return ducts of each zone, adjacent the air circulating apparatus, to balance the amount of supply and return air in each zone for reducing mixing of air between zones and stratification within a zone. Accurate and independent control of each zone in relation to the other zones in the building is thus permitted. The circular ducts are formed of sealed PVC or other suitable plastic material to improve the efficiency of the air delivery system both by reducing pressure losses and temperature losses conducted through the walls of the ducts.

Description:
FIELD OF THE INVENTION  
         [0001]    This invention relates to an air circulation system for buildings and the like and more particularly to an air circulation system for heating or cooling purposes.  
         BACKGROUND  
         [0002]    The use of an air circulation system in a building which incorporates air heating or cooling is well known for controlling the temperature, quality or quantity of air circulated within a building. The system usually incorporates a main blower which generates a flow of heated or cooled air via metal supply ducts to various zones within the building. Control of the temperature within the building is usually accomplished by varying the cycle duration of cooling or heating components of the circulation system, as called for by a thermostat. A plurality of return ducts returns air from the zones back to the blower through a main plenum. Control of the amount of circulation in each zone is usually accomplished by providing dampers in the branched runs and at the diffusers at the terminal ends of the supply ducts. The rectangular shape of the plenums causing air turbulence and the arrangement of the dampers in the branched runs and at the diffusers of the supply ducts however leads to substantial static pressure losses in the ducts and plenums. The conventional metal ducts are also known to leak due to the limitations of the metal construction and have poor efficiency due to the high conductivity of the metal. When drawing return air from the return ducts in such systems, the amount of air drawn from the respective zones of the building often varies uncontrollably, depending upon leaks in the return ducts and the location of the return ducts in relation to the blower, resulting in frequent and uncontrollable mixing of the air between zones and in zone stratification. This mixing or stratification results in a system which is inaccurate, difficult to control and provides discomfort to the building occupants. Further problems arise when it is desired to adjust the temperature or air quality of one zone in relation to another.  
         SUMMARY  
         [0003]    According to one aspect of the present invention there is provided a method of controlling air circulation in a building having plural zones, the method comprising:  
           [0004]    providing an air circulation apparatus having supply ducting arranged to discharge a flow of pressurised supply air from the apparatus and return ducting arranged to draw a flow of return air into the apparatus;  
           [0005]    providing at least one supply duct associated with each zone;  
           [0006]    coupling each supply duct in communication between the supply ducting and the zone associated with the supply duct;  
           [0007]    providing a damper on each supply duct adjacent to the supply ducting of the air circulation apparatus arranged to control the flow of supply air through the supply duct;  
           [0008]    providing at least one return duct associated with each zone;  
           [0009]    coupling each return duct in communication between the return ducting and the zone associated with the return duct;  
           [0010]    providing a damper on each return duct adjacent to the return ducting of the air circulation apparatus arranged to control the flow of return air through the return duct;  
           [0011]    adjusting the dampers on the respective supply ducts such that each zone receives a desired amount of the flow of supply air delivered thereto;  
           [0012]    adjusting the dampers on the respective return ducts such that the flow of return air through the return ducts of each zone is substantially equal to the flow of supply air delivered through the supply ducts to that zone.  
           [0013]    The supply and return ducting of the air circulation apparatus may comprise a manifold mounted directly on the respective take off plenum of the apparatus or in further embodiments, the ducting may designate collectively a manifold associated with each control region and the ducts extending therebetween. Providing a damper on each duct permits the control of flow through each duct dependent upon design needs.  
           [0014]    According to a second aspect of the present invention there is provided an air circulation system for a building having a plurality of zones, the system comprising:  
           [0015]    an air circulation apparatus having a supply outlet arranged to discharge pressurised supply air from the apparatus and a return inlet arranged to draw return air into the apparatus;  
           [0016]    a supply manifold coupled to the supply outlet of the air circulation apparatus;  
           [0017]    at least one supply duct coupled in communication between each zone and the supply manifold;  
           [0018]    a damper coupled to each supply duct adjacent the supply manifold and being arranged to control a flow of the supply air through the supply duct;  
           [0019]    a return manifold coupled to the return inlet of the air circulation apparatus;  
           [0020]    at least one return duct coupled in communication between each zone and the return manifold;  
           [0021]    a damper coupled to each return duct adjacent the return manifold and being arranged to control a flow of the return air through the return duct.  
           [0022]    According to a further aspect of the present invention there is provided a building having at least one control region comprising a plurality of zones and an air circulation system comprising:  
           [0023]    an air circulation apparatus having a supply outlet arranged to discharge pressurised supply air from the apparatus and a return inlet arranged to draw return air into the apparatus;  
           [0024]    said at least one control region having a supply manifold associated therewith, the supply manifold being coupled to the supply outlet of the air circulation apparatus;  
           [0025]    at least one supply duct coupled in communication between each zone of said at least one control region and the supply manifold associated with said at least one control region;  
           [0026]    a damper coupled to each supply duct adjacent the supply manifold of said at least one control region, the damper being arranged to control a flow of the supply air through the supply duct;  
           [0027]    said at least one control region having a return manifold associated therewith, the return manifold being coupled to the return inlet of the air circulation apparatus;  
           [0028]    at least one return duct coupled in communication between each zone of said at least one control region and the return manifold associated with said at least one control region;  
           [0029]    a damper coupled to each return duct adjacent the respective return manifold of said at least one control region, the damper being arranged to control a flow of the return air through the return duct.  
           [0030]    In practice, each control region of the building will generally comprise a floor, a group of floors of the building or a designated wing of the building. The zones would thus generally comprise one or more rooms within each control region which are joined to form a generally common area. The supply or returns ducts associated with each zone may comprise a single direct duct or may be branched adjacent to diffusers at the terminal ends to supply air to or draw air from different areas or rooms within the zone.  
           [0031]    The use of dampers on both the supply and return ducts adjacent the respective manifolds provides a convenient location to adjust all of the dampers of the system at one time for greater control of the distribution of the air. The use of dampers on the return ducts in particular permits the amount of supply air and return air in each zone to be balanced to reduce mixing of air between zones. This enables adjacent zones to have different air exchange rates and thus different temperatures in a heating or cooling system. Accurate and independent control of each zone in relation to the other zones in the building is thus permitted dependent upon design needs.  
           [0032]    The dampers on both the supply and return ducts are preferably commonly located adjacent the air circulation apparatus.  
           [0033]    The dampers of said at least one supply duct and the dampers of the respective said at least one return duct for each zone are arranged such that the flow of supply air is approximately equal to the flow of return air for each zone.  
           [0034]    There may be provided a single dedicated supply duct and a single dedicated return duct for each zone. The dampers of each dedicated supply duct and the respective dedicated return duct for each zone would preferably be arranged such that the flow of supply air is approximately equal to the flow of return air for each zone.  
           [0035]    The supply ducts and the return ducts may each comprise a rigid tube of circular cross section which is formed of plastic material, preferably PVC material.  
           [0036]    When using conventional PVC tubing, each of the supply and return ducts is formed of plural sections which are preferably sealed therebetween such that the ducts each form a continuous sealed passage from the respective manifold to the respective zone.  
           [0037]    There may be provided a boot on a free end of each supply and return duct arranged to mount the free end of the duct within a supporting surface of the respective zone. Each boot is preferably also formed of PVC material which is arranged to be mounted on the free end of the respective duct formed of PVC material in a sealed configuration therebetween. Canvas collars may couple the plastic tubing to the boots to allow for linear expansion and limit noise transfer due to vibration.  
           [0038]    When the air circulation apparatus comprises a conventional air handler for buildings, the supply and return manifolds are preferably arranged to be mounted directly onto respective supply and return plenum takeoffs of the air handler. The supply and return manifolds in this arrangement are preferably adapted to mount the respective supply and return ducts formed of PVC material directly thereon. Alternatively, a canvas collar may be used at the transition point to mount the PVC material onto the manifolds formed of metallic material, to allow for differing thermal expansion rates between the two materials, to allow for linear expansion and to lessen noise.  
           [0039]    The supply and return manifolds may include the dampers of the respective supply and return ducts mounted directly thereon.  
           [0040]    When the air circulation apparatus is arranged to selectively heat the air, cool the air or both, a thermostat may be associated with each zone. The thermostat could be arranged to control the respective dampers associated with the zone to accordingly control a temperature of the zone.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0041]    In the accompanying drawings, which illustrate an exemplary embodiment of the present invention:  
         [0042]    [0042]FIG. 1 is schematic view of the air circulation system according to the present invention.  
         [0043]    [0043]FIG. 2 is an isometric view of an air circulation apparatus for use with the system of FIG. 1.  
         [0044]    [0044]FIG. 3 is an alternative arrangement for an auxiliary manifold which includes an adjustable damper plate.  
         [0045]    [0045]FIG. 4 is an isometric view of the supply and return ducts in a portion of a building in a heating arrangement.  
         [0046]    [0046]FIG. 5 is an isometric view of the supply and return ducts in a portion of a building in a cooling arrangement.  
         [0047]    [0047]FIGS. 6A, 6B and  6 C are isometric view of various arrangements of boots arranged to mount the terminal end of a duct according to FIG. 1 in a supporting surface such as a wall or floor and the like.  
         [0048]    [0048]FIG. 7 is an elevational view of a collar mounting a terminal end of one of the ducts to a suitable mounting surface. 
     
    
     DETAILED DESCRIPTION  
       [0049]    Referring to the accompanying drawings, there is illustrated an air circulation system generally indicated by reference numeral  10 . The system  10  is arranged for circulating air having a primary control region  12  comprised of plural zones  14  within which the temperature and flow of Heating, Ventilation and Air Conditioning (HVAC) air therethrough are to be regulated. The system  10  may also be adapted for use with a building having one or more auxiliary control regions  16  which is also comprised of plural zones  14  to be regulated. Each control region of the building may comprise a floor, a group of floors of the building or a designated wing of the building whereas the zones generally comprise one or more rooms of the building which are joined to form a generally common area.  
         [0050]    The system  10  includes an air handler which is similar to conventional HVAC units. The air handler  18  includes a supply outlet defined by a supply plenum takeoff  20  for discharging a flow of pressurised supply air therethrough. A return inlet is also provided in the form of a return plenum takeoff  22  which is arranged to draw a flow of return air therethrough. A supply manifold  24  and a return manifold  26  are arranged to be mounted on the respective supply and return plenum takeoffs in place of the plenums found in a conventional system.  
         [0051]    Within the primary control region  12 , one or more supply ducts  28  is coupled between each zone and the supply manifold  24 . Accordingly, within the primary control region, one or more return ducts  30  is connected between each zone  14  and the return manifold  26 . Each duct is arranged to communicate directly between the respective manifold and the respective zone associated therewith. It is preferable to have a single dedicated supply duct in a single dedicated return duct for each zone for optimal control of the air flow through the zone, however it may be more economical to have a single return duct associated with plural supply ducts when the zone comprises a large open area encompassing several rooms.  
         [0052]    Each duct  28  or  30  may also include one or more branched sections  31  adjacent to the diffusers at the terminal ends of the ducts to supply air to or draw air from one or more areas or rooms within a zone. Each individual branched section would include an additional damper therein to be adjusted upon initial installation.  
         [0053]    A damper  32  is coupled to each duct  28  and  30  adjacent the respective manifold which is arranged to mount the damper thereon. In a building having a single primary region  12  both the supply and return dampers are commonly located adjacent the air handler  18 .  
         [0054]    When the building includes one or more auxiliary regions  16  an auxiliary supply manifold  34  and an auxiliary return manifold  36  are associated with each region  16 . The auxiliary manifolds are located adjacent the respective auxiliary region associated therewith remotely from the air handler  18 . An oversized duct  38  communicates between each auxiliary manifold and the respective plenum takeoff  20  or  22 . Supply and return ducts are arranged in the auxiliary regions and coupled between each zone of the region and the respective auxiliary manifold in a similar manner as in the primary region  12  with dampers being located on each duct adjacent the respective manifold.  
         [0055]    As illustrated in FIG. 3, an alternate auxiliary manifold  108  is provided for use when the oversized duct  38  is branched into two ducts  28 . An adjustable damper plate  110  is pivotally mounted between the ducts  28  at the manifold  108  to vary the amount of air diverted to each duct. A control rod  112  is provided to adjust the position of the damper plate.  
         [0056]    Each of the ducts are formed of conventional PVC pipe which is rigid and circular in cross section. The supply and return manifolds  24  and  26  are adapted to mount the PVC pipe directly thereon. As illustrated in FIG. 7, a canvas collar  100  may be provided for mounting a terminal end of one of the ducts designated by reference numeral  102 , to a suitable mounting surface  104 , which may comprise either a boot as illustrated in FIG. 6 and described in the following or one of the manifolds  24  or  26 .  
         [0057]    The ducts are thus assembled from pre-formed sections which are sealed upon assembly between each respective section so as to form a continuous sealed passage between the respective manifold and the respective zone associated therewith. As illustrated in FIG. 4, the oversized duct  38 , which may act as an auxiliary manifold, can also be formed of tubular PVC material.  
         [0058]    As illustrated in FIGS. 6A through 6C, various boots  40  are illustrated for mounting on the respective terminal free ends of the supply and return ducts. Each boot is formed of PVC material similarly to the ducts for securement thereto in a sealed configuration using appropriate sealant. Each boot includes an appropriate male connector  42  or female connector  44  for mounting on the terminal free end of the respective duct. The boots are thus adapted to mount the free ends of the respective ducts in an appropriate supporting surface such as a wall or floor of the appropriate zone associated therewith. As described above in regard to FIG. 7, the boots may also incorporate canvas collars  100  at the transition point between the ducts and the boots.  
         [0059]    The control of the dampers  32  may be arranged manually or through a control system  46 . When manually adjusting the dampers the overall flow requirements of the building to achieve the required heating or cooling within the respective zones of the building must first be determined. With the dampers initially all opened approximately only ¾ of their fully opened position, an operator may manually partially close selected dampers on the supply ducts  28  to any desired degree to achieve a desired flow of supply air to each zone of the building.  
         [0060]    Subsequently each damper on the return ducts  30  is then partially closed by a desired amount to achieve a balance between the flow of return air from each zone with the flow of supply air to that zone. Further adjustment of selected dampers on both the supply and return ducts may be then required to ensure that the combined flow of supply air through all supply ducts in a given zone is substantially equal to the combined flow of return air through all return ducts within that zone.  
         [0061]    When using a single dedicated supply and a single dedicated return duct within each zone the damper on the respective supply duct is arranged similarly to the damper on the respective return duct in order to achieve a balance of supply air and return air within a given zone.  
         [0062]    To monitor the use of the air circulation system, a control system  46  employing programmable logic controllers may be used. The control system  46  would include a thermostat  48  located within each zone  14  of the building. The thermostats  48  would be arranged to monitor the temperature within the respective zones and relay appropriate control signals back to the control system  46  which would then actively open or close selected supply and return dampers to adjust the amount of heating or cooling air being supplied to a given zone. Flow meters could be incorporated into the system to ensure that the flow of return air is substantially equal to the flow of supply air within each selected zone regardless of the different flow requirements among the different zones.  
         [0063]    The air circulation system  10  is intended to be a complete air delivery system which includes both a heating and cooling source. The first step in setting up the system  10  is to perform heat loss or heat gain calculations (as per most North American Building Codes). The geographical location will determine which calculation is necessary, heat loss or heat gain. From that calculation the heating and/or cooling capacities can be determined. The total air volume of the air circulation system  10  can then be determined by the desired heat rise and/or heat fall necessary for a particular geographic location.  
         [0064]    Ideally the air circulation system  10  would utilise a horizontal furnace/air handler to avoid pressure losses from the typical three transitions which are a product of the standard upright version. To simplify the understanding of the air circulation system  10 , an upright furnace/air handler is described and illustrated as these are the most popular style.  
         [0065]    The air circulation system  10  incorporates a custom-made, galvanized steel, vertical supply air plenum or bonnet adapted to mount directly on the air handler  18 . The supply air plenum comprising the supply manifold  24  incorporates turning vanes and/or a gentle corner with an inside radius of at least ⅓ of the duct width to reduce pressure loss. The vertical return air plenum comprising the return manifold  26  will also be made of galvanized steel and includes the same pressure loss reduction methods of vanes and/or gentle tapering at each transition. Both the supply and return plenums may be insulated to lower tempering losses through the conductive metal. The air handler includes a fan motor which is preferably of the centrifugal or ECM type.  
         [0066]    At the metal supply and return air vertical plenums, a transition will take place to solid round ducting, preferably plastics, for example PVC tubing and the like. This transition will take place through the dampers  32  formed of metal on both the supply and return air vertical plenums to carefully control air flow. The supply air plenum may incorporate a plenum box creating a small horizontal facet to the vertical plenum dependent on furnace/air handler orientation. The solid ducting (supply and return) will be completely sealed (preferably glued) right to its targeted zone.  
         [0067]    Transition fittings will be at 45° maximum where possible to minimize pressure losses. Sealing (preferably gluing) is necessary to limit air pressure losses, air mixing, dirt infiltration and supply and return air imbalances. Plastics are the preferred duct medium because of the limited conductive heating and/or cooling losses. The round ducting allows for a reduction of air friction losses due to turbulence caused by rectangular ducts. Round plastic ducting further reduces air friction because of it&#39;s smooth nature, as compared to conventional metal and thus will not accumulate dust and dirt as readily.  
         [0068]    The locations of the air distribution supplies and returns are vital to efficient operation and occupant comfort in the air circulation system  10 . For geographic regions where the primary function of the air circulation system  10  is heating, a duct arrangement for a given zone in the system is indicated generally by reference numeral  60  in FIG. 4. For geographic regions where the primary function of the air circulation system  10  is cooling, a duct arrangement for a given zone in the system is indicated generally by reference numeral  72  in FIG. 5.  
         [0069]    As illustrated in FIG. 4 for heating, the supply outlets  62  should be located in the floor at the outside wall  64 , underneath a window  66  where applicable. This outlet location, together with a diffuser which provides a wide spread in the air jet pattern, will allow for a consistent dilution of the cool air in the stagnant region. Cold air return  68  locations should be at floor levels on side walls  70  opposite to that of the supply, to remove the cooler air from the stagnant area in that particular zone.  
         [0070]    As illustrated in FIG. 5 for cooling, the supply outlets  74  should be mounted high on partition walls  76  opposite the outside walls  78  and/or windows  80  and utilise a diffuser with a non-spreading air jet pattern. That combination of the proper location and type of outlet will allow for consistent dilution of the hot air in the stagnant area. The hot air return  82  locations should also be high on a partition wall  76 , very close to the outside wall  78  and as far from the supply outlet  74  as possible, to remove hot air from the stagnant area in that particular zone.  
         [0071]    In geographic regions where heating and cooling functions are performed by the air circulation system, the heating duct arrangement  60  of FIG. 4 for supply outlet  62  and return outlet  68  locations should be utilised, with the air handler incorporating a 2 speed fan motor which can operate on a high speed in the cooling season. Supply air outlets  62  should be utilised which have both a heating and cooling position. The heating position comprises a wide spreading pattern while the cooling position comprises a non-spreading air distribution pattern.  
         [0072]    The intent of the air circulation system  10  is to relay hot or cold air from a supply source to a targeted destination or zone of a building in an efficient and accurate manner. The air is relayed through a low air resistance medium that also conserves the air temperature. System accuracy comes from controlled supply and return air flows through dampers on both the supply and return vertical plenums right at the air handler  18 . The system  10  will better serve building zones with greater heating or cooling losses, reducing stratification effects and instances of differential temperatures in areas on the same level of a building. Tempered air can be relayed effectively and efficiently through to 2nd floor areas and other auxiliary control regions. Heating/cooling and air flow losses are minimised because of the low thermal conductivity of the air transfer medium and the method of installation. The air circulation system  10  allows heating/cooling sources to be properly sized because of the ability to distribute the tempered air effectively and efficiently to targeted zones. When air handlers of conventional heating, ventilating and air conditioning systems are replaced with the air circulation system  10 , the size of the heating/cooling source can be reduced in many instances.  
         [0073]    The air circulation system  10  is advantageous in many ways as it can improve building occupant comfort, reduce utility costs, produce a cleaner living or working environment and reduce greenhouse gas emissions. Accuracy is accomplished by the ability to damper both the supply and return air ducts at the source. This will allow proper quantities of heating or cooling air to be delivered to different areas of a building dependent on requirements, creating a controllable system. Heating and/or cooling system response times can be instantaneous and ventilation air will be delivered more accurately to the building. Automatic zone control and/or zone customising can be easily performed to provide variations suited to one&#39;s own personal needs. For example, an elderly parent living together with his or her children may require additional heat.  
         [0074]    Selection of PVC duct material provides that duct temperature losses are minimised due to the low thermal-conductivity of the plastic ducts. Since the system is sealed, the only dirt, dust that will enter will be directly from the targeted area. The air circulation system will also not accumulate as much dust and dirt as conventional systems because of it&#39;s smooth nature. Furthermore the ducting material will not deteriorate under varying environmental conditions like: salt water air, high humidity. The PVC ducts are also comparable in cost to a conventional metallic duct system.  
         [0075]    While one embodiment of the present invention has been described in the foregoing, it is to be understood that other embodiments are possible within the scope of the invention. The invention is to be considered limited solely by the scope of the appended claims.