FRESH AIR VENTILATION CONTROL SYSTEM
This disclosure relates to a fresh air ventilation (FAV) controller. The FAV controller may include multiple input devices for setting a target fresh air ventilation flow rate (FAVFR), an operating FAVFR for an air handler, an operating FAVFR of a first ventilation appliance, an operating FAVFR of a second ventilation appliance. The FAV controller further includes electric interfaces adapted to couple to the air handler and a thermostat for controlling the air handler, a sensor for monitoring an operation of the first ventilation appliance, the second ventilation appliance, a thermometer for monitoring temperature of fresh air in a ventilation path to the air handler, and a motorized damper disposed in the fresh air ventilation path. The FAV controller may be configured to monitor operation times of the air handler, the first ventilation appliance, the second ventilation appliance, and the thermometer via the electric interfaces, and to control the air handler and the motorized damper, and/or the second ventilation appliance via the electric interfaces.
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This application is based on and claim priority to U.S. Provisional Application No. 62/550,878, filed on Aug. 28, 2017 and entitled “Fresh Air Ventilation Control System”, the entirety of which is herein incorporated by reference.
TECHNICAL FIELDThis disclosure relates to fresh air ventilation control (FAVC) and directs particularly to a versatile FAVC device and method for balanced and constrained ventilation.
BACKGROUNDAir-conditioned and sealed residential or commercial constructions may be required under applicable building codes to implement proper fresh air ventilation (FAV). FAV is traditionally achieved via a fresh air duct connected to a return path of a central air handler for drawing outside air into the building when a central fan of the central air handler is activated. Alternatively or additionally, FAV may be provided via unsealed openings, windows/doors that are intermittently opened, and/or the fresh air duct when other exhaust appliances, such as a bathroom exhaust fan, a water heater, a dryer, a fireplace, and a range hood, are in operation. The ventilation by the central fan and the ventilation by other exhaust appliances, however, are independent of one another.
SUMMARYThis disclosure is directed to a FAVC device and method for balanced and constrained fresh air ventilation.
In one implementation, an FAV controller is disclosed. The FAV controller may include a first input device for setting a first fresh air ventilation flow rate (FAVFR) as a target for a continuous fresh air ventilation, a second input device for setting a second FAVFR of an air handler when in operation, and a third input device for setting a third FAVFR of a first ventilation appliance when in operation. The FAV controller may further include a first electric interface adapted to couple to the air handler and a thermostat for controlling the air handler, and a second electric interface adapted to couple to a sensor for monitoring an operation of the first ventilation appliance. The FAV controller may further include a system circuitry configured to, in a consecutive first cycle and second cycle of multiple control cycles, monitor an effective FAVFR of the first ventilation appliance during the first cycle based on the third FAVFR and an operation time of the first ventilation appliance during the first cycle measured via the second electric interface; monitor, via the first electric interface, an effective FAVFR of the air handler during the second cycle based on the second FAVFR and an operation time of the air handler during the second cycle under the control of the thermostat; and generate a control signal for obtaining supplemental fresh air ventilation during the second cycle when a sum of the effective FAVFR of the ventilation appliance and the effective FAVFR of the air handler is less than the first FAVFR.
In an alternative implementation, another FAV controller is disclosed. The FAV controller may include first input device for setting a first fresh air ventilation flow rate (FAVFR) as a target for a continuous fresh air ventilation, a second input device for setting a second FAVFR of an air handler when in operation, a third input device for setting a third FAVFR of a first ventilation appliance when in operation, and a fourth input device for setting a fourth FAVFR of a second ventilation appliance when in operation. The FAV controller may further include a first electric interface adapted to couple to the air handler and a thermostat for controlling the air handler, a second electric interface adapted to couple to a sensor for monitoring an operation of the first ventilation appliance, a third electric interface adapted to couple to the second ventilation appliance, a fourth electric interface adapted to couple to a thermometer for monitoring temperature of fresh air in a ventilation path coupled to a return path of the air handler, and a fifth electric interface adapted to couple to a motorized damper disposed in the fresh air ventilation path. The FAV controller may further include a system circuitry configured to monitor operation times of the air handler, the first ventilation appliance, the second ventilation appliance, and the thermometer via the first, the second, the third, and the fourth electric interfaces; and control the air handler and the motorized damper, and/or the second ventilation appliance via the first, the third, and the fifth electric interfaces.
Fresh air ventilation (FAV) is essential for maintaining indoor air quality in residential, commercial, industrial, and other settings. In the U.S., for example, ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers) Standard 62.1 specifies various residential FAV requirements and recommendations to builders and building code designers. In particular, ASHRAE Standard 62.2 specifies an average continuous FAV flow rate recommendation of a residence according to a total floor area and number of rooms or sections. FAV may be obtained by activation of exhaust appliances such as a central air handler, water heaters, exhaust boosters, bathroom exhaust fans, a dryer, a fireplace, and a range hood. The air exhausted by these appliances may be replaced with fresh air via a window, door, and other unsealed openings, and additionally, via a FAV duct coupled to a central air handler and installed with a controllable motorized damper. Further, appliances with high exhaust flow rates or air consumptions, such as certain types of fireplaces and kitchen range hoods, may require makeup air, necessitating an installation of fresh air intake ducts by most building codes.
The various appliances above, when activated, may produce various exhaust flow rates. The activation of these devices may or may not be controllable by a central device. For example, a bathroom exhaust fan may be manually turned on and off at any time for random durations rather than being automatically controlled. On the other hand, an FAV resulting from fresh air drawn into the building by running the central air handler may be controllable by a thermostat coupled to the central air handler. Some exhaust fans may be installed with dedicated controllers that automatically turn on and off the exhaust fans based on, e.g., humidity (in a bathroom for example), temperature, and other parameters.
The FAV duct coupled to the central air handler may draw outside fresh air into an air return path of the central air handler when a central fan of the central air handler, alternatively referred to as a central air blower, is activated. In additional to the central fan for inducing FAV (as well as internal air circulation), the central air handler may further include a combination of a furnace plenum and a cooling coil or a single heat pump coil for conditioning temperature of the inside air. The cooling coil or heat pump coil may be coupled to an exterior compressor and an expansion valve for circulating refrigerant. Cooling and heating cycles may be controlled by a thermostat having a thermometer for measuring the indoor temperature. The fresh air that flows from the FAV duct into the return path of the central air handler may be excessively moist and may induce condensation in the central air handler. While the cooling coil or heat pump coil may be built to handle condensation as a norm and thus may be affected very little by humid return air, condensation on a fossil fuel based furnace plenum, however, may cause gradual life-shortening corrosion.
The disclosure below relates to FAVC devices that can be custom configured to interface with the central air handler, the thermostat, the motorized damper, and other exhaust appliances for setting, monitoring, and controlling these appliances in a holistic manner to achieve a balanced FAV that satisfies an average continuous FAV flow rate target specified by the ASHRAE Standard 62.2, subject to humidity and temperature constraints. The FAVC device disclosed below may be adapted to integrate with and control a wide range of exhaust appliances, including energy recovery ventilation (ERV) or heat recovery ventilation (HRV) systems. Further, the FAVC devices disclosed below are flexibly configured to function with a central air handler having fossil fuel based furnace plenum as well as a single heat pump coil, and to control the ventilation to protect the furnace plenum from condensation-induced corrosion. Other advantages and improvements of the disclosed FAVC devices over traditional ad hoc ventilation systems will become apparent in the detailed description below.
The central air handler 110 may include a port 111 for returning air from the residence to the central air handler, a port 117 for supplying and distributing air to various locations in the residence, a central fan 112, a furnace with plenum 114, a heat exchanger with cooling coil 116 coupled to a compressor for refrigerant 118 disposed outside of the residence 102. When the central fan 112 is in operation, the return air in port 111 flows through the furnace plenum 114 followed by the cooling coil 116 and is distributed throughout the residence. The furnace may be coupled to and controlled by the thermostat 150 disposed in a suitable location in the residence 102. The thermostat 150 may include temperature and humidity sensors for controlling the central air handler 110 to providing heating and cooling. The central fan 112 may operate at different speed for cooling and heating. The furnace or furnace plenum 114 may be based on combustion of fossil fuels such as oil and natural gas. The furnace thus may need to draw combustion air from the residence to be mixed with the fossil fuel. The required combustion air may be drawn into the furnace combustion chambers through a furnace grill. The combustion exhaust may be taken out of the residence via a furnace exhaust duct 115. A draft pipe from the outside of the residence to a location near the furnace for replenish combustion air may further be installed (not shown in
The central air handler may be further coupled to an FAV duct 120 at the return path 111. The FAV duct 120 may be extended to exit to outside of the residence 102. A motorized damper 124 may be installed in the FAV duct 120 to facilitate the control of flow of fresh air into the return path 111 of the central air handler from the outside. The motorized damper 124 may be placed close to the exit or a vent hood of the FAV duct 120, or alternatively, may be disposed anywhere along the FAV duct 120. An outdoor temperature (ODT) sensor or thermometer 126 may be installed in the FAV duct 120 to measure the temperature of the air flowing from outside of the residence into the return path 111 of the central air handler. Sensor or thermometer 126 is referred to as an outdoor temperature sensor but does not need to be installed outdoors. The purpose of the ODT sensor 126 is to monitor the incoming fresh air temperature before being mixed with the air returning to the central air handler 110. As such, the ODT sensor 126 may be installed after the motorized damper 124 but before the location of the coupling between the FAV duct 120 and the return path 111 of the central air handler 110. For example, a ¼ inch hole may be drilled into the FAV duct 120 and the ODT sensor may be inserted into the FAV duct via the drill hole and the drill hole may then be sealed with metal duct tape.
The exhaust fans 128 and 132, for example, may be installed in bathrooms. They may be controlled by traditional manual wall switches. Alternatively and additionally, an ERV/HRV system may replace, e.g., the exhaust fan 128, the exhaust duct 130, and the FAV duct 120. For example, as shown by 170 of
Other appliances such as clothes dryer 136, kitchen range hood 140, and fireplace 190, when in operation, may take air out of the residence with high flow rates. Some of these appliances, such as the fireplace 190 and/or the kitchen range hood 140 may require makeup air, which may be sufficiently supplied by natural drafting for large residence, or may require a makeup air duct in tandem operation with these appliances (not shown in
A central component of this disclosure, the FAV controller 160, monitors and controls at least some of the multiple appliances above to achieve ventilation requirements specified in the ASHRAE Standard 62.2 while maintaining quality of indoor air and protecting the furnace plenum from excessive moisture and condensation. The FAV controller 160, for example, may monitor and control the FAV periodically, e.g., in 30 minutes cycles, so that ventilation requirement is satisfied on average and in each ventilation cycle.
Ftarget=0.03Afloor+7.5(Nbr+1) (1)
where Ftarget is the required or target continuous ventilation rate in cfm (cubic feet per minute), Afloor is the floor area of the residence (ft2), and Nbr is the number of bedrooms (not to be less than 1) in the residence. As such, a 4-bedroom residence having 3000 ft2 requires about 130 cfm ventilation on a continuous flow basis. The FRSD 202 may be set accordingly.
FRSDs 204 and 206 may be used to set operational flow rates for the central fan in heating and cooling modes, Fheat and Fcool, respectively. The FRSDs 204 and 206 may be used to set Fheat and Fcool in a range of, for example, from 25 cfm up to 700 cfm. These operational flow rates may only include the flow rate of fresh air into the residence via the FAV duct 120 of
The FRSDs 210, 212, 214, and 216 may be used for setting operational flow rate of various exhaust appliances other than the central fan. As will be described in more detail later, operation of the various exhaust appliances may be monitored by the FAV controller 160 and the fresh air ventilation as a result of such operation during a ventilation cycle may be tracked by the FAV controller and credited towards and reduce ventilation required in one or more future ventilation cycles. The FRSDs 210, 212, 214, and 216 may each be configured with various flow rate-setting ranges for monitoring different types of exhaust appliances. For example, FRSD 210 may be configured as a rotary dial with multiple settable levels between 25-225 cfm for monitoring a bathroom exhaust fan. For another example, FRSD 212 may be configured as a rotary dial with multiple settable levels between 20-140 cfm for monitoring another smaller bathroom exhaust fan. The FRSD 214 may be configured as a rotary dial with multiple settable levels between 80-400 cfm for monitoring medium high flow rate exhaust appliances such as the clothes dryer 136 of
As further shown in
Continuing with
The FAV controller 160 may further include an outdoor temperature (ODT) monitoring interface with terminals S (260 of
Continuing with
The FAV controller may further include a mode selector 250 for setting various mode of ventilation control operation. In one exemplary implementation, the mode selector 250 includes four dipswitches 252, 254, 256, and 258 (positions 4, 3, 2, and 1). For example, as shown in Table 1 below, the dipswitches at positions 1 and 2 may be used for specifying a climate setting; the dipswitch at position 3 may be used for specifying a central fan circulation control mode; and the dipswitch at position 4 may be used to specify an energy mode for the FAV controller 160.
Specifically, the climate mode specified by the dipswitches at positions 1 and 2 of the mode selector 250 may be used to determine constraints and conditions on the ventilation control by the FAV controller 160 during each ventilation cycle based on climate. The effect of these constraints and conditions will be described in more detail below. The central fan circulation control mode specified by the dipswitch at position 3 of the mode selector 250 may be used to determine whether the FAV controller needs to bypass the thermostat fan control and force the central fan to turn on when the FAV controller detects an operation of a particular exhaust appliance. In one exemplary implementation, the central fan circulation control mode may be tied to an appliance monitored by the appliance monitoring terminals A3/AC3 (245 and 246 of
The energy mode set by the dipswitches at position 4 of the mode selector 250 specifies whether the FAV controller controls ventilation in a normal mode or in an energy saving mode. In the energy saving mode, for example, additional ventilation required in each ventilation cycle after taking into account the ventilation by the central fan under the control of the thermostat during heating or cooling calls may be obtained by controlling an exhaust appliance (e.g., an exhaust appliance coupled to an efficient ERV/HRV setup such as 170 of
The FAV controller of
As illustrated by the exemplary implementation 500 of
Specifically, if the monitored operation time for an exhaust appliance coupled to terminals A1/AC1 (terminals 241 and 242 of
tA1-Normalized=tA1-actual*FA1/Ftarget (2)
where Ftarget is the target continuous flow rate as specified by the ASHRAE Standard 62.2 via Equation (1) and set in the FAV controller 160 by the FRSD 202 of
In one implementation, the normalized operational times tA1-Normalized, tA2-Normalized, tA3-Normalized, and tA4-Normalized (or the credit timer values) may be capped. For example, appliances with relatively small ventilation flow rates, such as those exhaust fans monitored by the A1/AC1 and A2/AC2 terminals of the FAV controller, may be limited to 30 minutes, or one ventilation cycle worth of credit. Appliances with medium ventilation flow rates such as a clothes dryer monitored by the A3/AC3 terminals of the FAV controller may be capped at 60 minutes, or two ventilation cycles worth of credit. Appliances with high flow rates such as those monitored by the A4/AC4 terminals of the FAV controller, on the other hand, may be limited to 240 minutes, or eight cycles worth of credit.
In some other implementation, the normalized operation times tA1-Normalized, tA2-Normalized, tA3-Normalized, and tA4-Normalized (or the credit timer values) may further be weighted downwards considering that some appliances may not obtain the full specified ventilation flow rates, when, for example, the motorized damper is closed when the appliances are in operation, and draft of fresh air into the residence may not be sufficient for the appliances to exhaust at the specified flow rates. The weighting factor may be predetermined for each appliance. The operation state of the damper may be further monitored (via the V terminals of the FAV controller of
In one implementation, the appliance monitoring process 508 may be used to enable other functions and controls by the FAV controller 160. For example, a high flow rate appliance requiring makeup air may be monitored by the A4/AC4 terminals of the FAV controller. The FAV controller may be configured to force the motorized damper to open via the V terminals of the FAV controller and force the central fan to operate when it detects that the high flow rate appliance is in operation, irrespective of whether a fresh air ventilation call is needed during the ventilation cycle, whether heating/cooling is active, or whether there are any humidity and temperature constraints. For another example, some high flow rate appliance, such as a clothes dryer, may cause local ventilation that is unbalanced at the level of the entire residence. This type of appliances may be monitored by the A3/AC3 terminals of the AV controller. By setting a central fan circulation control mode specified by the dipswitch at position 3 of the mode selector 250 of
Continuing with the logic flow of
Optionally in one implementation, when a beginning of a heating or cooling call is detected in process 504 of
Continuing with
In process 502, once all the credit timers lapse during the current ventilation cycle (after tc, 519), the FAV controller may perform ventilation call 512 for a duration tv (514) such that the ventilation target for the current cycle is satisfied. During the ventilation call, various constraints and conditions may be monitored (516) by the FAV controller and the ventilation call may be terminated or the ventilation duration may be reduced when the constraints and conditions prohibit a full ventilation for, e.g., the protection of the furnace plenum from condensation. Once the ventilation target is satisfied, the ventilation call ends and the ventilation cycle continues for an idle period ti (518) until the current ventilation cycle ends and the FAV controller enters the next ventilation cycle.
The process 509 of
tv=(ttarget−tc)*Ftarget/Fexp (3)
where Fexp is an expected ventilation flow rate during the ventilation call. The expected ventilation flow rate depends on which and how many ventilation appliances are expected to be in operation for the ventilation call.
Thus, as shown in
However, if the FAV controller detects that heating/cooling is not active (branch 603 of
Continuing with
Continuing with
Following step 622 of
Following step 626 of
The ventilation call 512 of
As shown in
For another example in
For another example, the FAV controller may be further configured to prohibit ventilation when it determines that the mixed ventilation air and return air at the central air handler is below a low mixed air temperature threshold Tlow-mixed, e.g., Tlow-mixed=55° F. The FAV controller may determine the mixed air temperature using the ODT sensor reading and its built in indoor thermometer 310 of
Further, as shown in
The various thresholds temperatures and threshold RHs in
In the implementations described above with respect to
Compressor monitoring further allows for improved conditional and/or constrained ventilation (process 516 of
Examples of conditional/restrained ventilation based on temperature for these implementations utilizing the compressor signal are described below. When the ODT sensor (126 of
Examples of conditional/restrained ventilation based on relative humidity for these implementations utilizing the compressor signal for ODT temperature above 70° F. are further described below. When the indoor RH is below, e.g., 50%, the FAV controller may not further restrict ventilation beyond what was described above for temperature restriction. When the indoor RH is above 50% but below, e.g., 55%, the FAV may require compressor to be active for ventilation via the V terminal (234 of
Examples of conditional/restrained ventilation based on relative humidity for these implementations utilizing the compressor signal for ODT temperature below 70° F. are further described below. When the indoor RH is below, e.g., 50%, the FAV controller may not further restrict ventilation. When the indoor RH is above 50% but below, e.g., 55%, a dehumidification function may be enabled but not active unless outdoor temperature is below 40° F. When the indoor RH is above 55%, a dehumidification function may be activated and ventilation may be permitted if heat (W) or compressor (Y) signals are present. The dehumidification process requires that indoor RH drops during a timed duration while ventilation is active. If humidity levels rise, while dehumidification process is active, ventilation will be disabled until indoor RH falls below 50%. When outdoor temperature rises above 40° F., the dehumidification mode may be disabled and ventilation may not be permitted.
An exemplary logic flow for ventilation call conditioned on compressor signal Y for ODT higher than 70° F. as described above is shown as 800 in
An exemplary logic flow for ventilation call conditioned on the compressor (Y) and heating (W) signal for ODT lower than 70° F. is shown in
The FAV controller disclosed above is configured to independently monitor up to four exhaust appliances. The FAV controller may monitor a wide range of types of appliances, with their operational flow rate flexibly configured via the FRSDs. Each of the four pairs of monitoring terminals may be wired to monitor a group of appliances rather than a single appliance. As such, the FAV controller disclosed above may be capable of monitoring more than four individual appliances, as long as the sum of the flow rates within each appliance group does not exceed the maximum setting of the corresponding FRSD. The FAV controller further provides control over a single or a group of exhaust appliances and control over the central fan, bypassing the thermostat if needed for ventilation. The ventilation is controlled periodically to satisfy a target continuation FAV flow rate subject to constraints and conditions designed to protect the furnace plenum from condensation. The constraints and conditions are monitored by the FAV controller via various humidity and temperature sensors. The monitored operation of various exhaust appliances is credited to the ventilation target, providing energy savings and preventing over ventilation. The FAV controller further provides a dual mode ventilation control (normal mode and energy saving mode) and multiple climate modes.
In some other implementations, a progressive restraint on ventilation druing ventilation calls may be used depending on the RH level. For example, the progressive ventilation may be implemented in a plurality of progressive levels (rather an a two-level implementation of either 25% or 100% discussed in the implementations above). In particular, when the FAV controller determines to proceed with a ventilation call during a ventilation cycle, it may calculate the ventilation run time and then reduce the run time according to the RH level as monitored by the FAV. For example, when the RH is below 50%, the ventilation run time may not be reduced. When the RH is between e.g., 50% and 52%, the ventilation run time during the current ventilation cycle may be reduced to 75%. When the RH is between e.g., 52% and 55%, the ventilation run time during the current ventilation cycle may be reduced to 50%. When the RH is between e.g., 55% and 60%, the ventilation run time during the current ventilation cycle may be reduced to 25%. When the RH is above e.g., 60%, the ventilation may be prohibited during the current ventilation cycle. The progressive ranges of RH and corresponding amount of ventilation reduction above are mere examples and are not limiting. Progressive ventilation with finer granularity or continuous progression may be similarly implemented. The progressive ventilation may be implemented in the cooling mode or both in the cooling mode and heating mode. Such progressive ventilation may be particularly relevant to the cooling mode because throttling the amount of ventilation progressively downward depending on RH levels would provide less damaging condensation at the furnace plenum during cooling where the furnace is not active.
In yet some other implementations and when a ventilation prohibition condition occurs (e.g., when RH is above 60%, or under any other prohibition condition discussed or not discussed above), the ventilation would be prohibited but the FAV controller may allow forced ventilation when the prohibition period persists longer than a preset threshold. For example, if the prohibition condition persists for more than, e.g., 4 hours, the FAV may allow one or more cycles of ventilation. For example, the FAV may reset a timer and begin countdown when a prohibition starts. If the prohibition condition persists and no ventilation is performed during the countdown, the FAV may allow ventilation after the timer counts down to zero. Such forced ventilation may be permitted for one or more ventilation cycles and if the prohibition condition persists, the FAV may restore prohibition, reset the timer, and begin a next countdown. Such ventilation under prohibition condition is aimed at providing at least some amount of ventilation during an otherwise long prohibition stretch. In some implementations, such ventilation may be provided at a reduced level, e.g., 25%. In order to reduce potential life-reducing damage to the heating/cooling system, in some implementations, such ventilation may only be allowed when cooling or heating is active as monitored by the FAV controller as discussed above.
In the detailed disclosure above, terminology may be understood at least in part from usage in context. For example, terms, such as “and”, “or”, or “and/or,” as used herein may include a variety of meanings that may depend at least in part upon the context in which such terms are used. Typically, “or” if used to associate a list, such as A, B or C, is intended to mean A, B, and C, here used in the inclusive sense, as well as A, B or C, here used in the exclusive sense. In addition, the term “one or more” as used herein, depending at least in part upon context, may be used to describe any feature, structure, or characteristic in a singular sense or may be used to describe combinations of features, structures or characteristics in a plural sense. Similarly, terms, such as “a,” “an,” or “the,” again, may be understood to convey a singular usage or to convey a plural usage, depending at least in part upon context. In addition, the term “based on” may be understood as not necessarily intended to convey an exclusive set of factors and may, instead, allow for existence of additional factors not necessarily expressly described, again, depending at least in part on context.
The illustrations of the implementations described herein are intended to provide a general understanding of the structure of the various embodiments. The illustrations are not intended to serve as a complete description of all of the elements and features of apparatus and systems that utilize the structures or methods described herein. Many other implementations may be apparent to those of skill in the art upon reviewing the disclosure. Other implementations may be utilized and derived from the disclosure, such that structural and logical substitutions and changes may be made without departing from the scope of the disclosure. Additionally, the illustrations are merely representational and may not be drawn to scale. Certain proportions within the illustrations may be exaggerated, while other proportions may be minimized. Accordingly, the disclosure and the figures are to be regarded as illustrative rather than restrictive.
Claims
1. A fresh air ventilation control (FAVC) system comprising:
- a first input device for setting a first fresh air ventilation flow rate (FAVFR) as a target for a continuous fresh air ventilation;
- a second input device for setting a second FAVFR of an air handler when in operation;
- a third input device for setting a third FAVFR of a first ventilation appliance when in operation;
- a first electric interface adapted to couple to the air handler and a thermostat for controlling the air handler;
- a second electric interface adapted to couple to a sensor for monitoring an operation of the first ventilation appliance;
- a system circuitry configured to, in a consecutive first cycle and second cycle of multiple control cycles: monitor an effective FAVFR of the first ventilation appliance during the first cycle based the third FAVFR and an operation time of the first ventilation appliance during the first cycle measured via the second electric interface; monitor, via the first electric interface, an effective FAVFR of the air handler during the second cycle based on the second FAVFR and an operation time of the air handler during the second cycle under the control of the thermostat; and generate a control signal for obtaining supplemental fresh air ventilation during the second cycle when a sum of the effective FAVFR of the ventilation appliance and the effective FAVFR of the air handler is less than the first FAVFR.
2. The FAVC system of claim 1, further comprising:
- a fourth input device for setting a fourth FAVFR of a second ventilation appliance when in operation;
- a third electric interface adapted to couple to the second ventilation appliance; and
- a mode selector for setting the FAVC system to one of a normal mode and an energy-saving mode,
- wherein the control signal is sent to the second ventilation appliance via the third electric interface for obtaining the supplemental fresh air ventilation and is prevented from being sent to the air handler when the mode selector is set to the energy-saving mode, and is sent to both the second ventilation appliance and the air handler for obtaining the supplemental fresh air ventilation when the mode selector is set to the normal mode.
3. The FAVC system of claim 2, wherein a duration of the control signal is determined by:
- a difference between the first FAVFR and the sum of the effective FAVFR of the ventilation appliance and the effective FAVFR of the air handler; and
- the fourth FAVFR when the mode selector is set to the energy-saving mode or a sum of the second FAVFR and the fourth FAVFR when the mode selector is set to the normal mode.
4. The FAVC system of claim 1, further comprising a fourth electric interface adapted to couple to a motorized damper disposed in a fresh air ventilation path coupled to a return path of the air handler, wherein the system circuitry is further configured to keep the motorized damper open during the supplemental fresh air ventilation.
5. The FAVC system of claim 4, further comprising:
- a third electric interface adapted to couple to a second ventilation appliance,
- wherein the system circuitry is further configured to monitor the second ventilation appliance via the third electric interface and keep the motorized damper open when the second ventilation appliance is in operation.
6. The FAVC system of claim 1, further comprising a fourth electric interface adapted to couple to a thermometer for monitoring temperature of fresh air in a ventilation path coupled to a return path of the air handler, wherein a duration of the control signal for obtaining supplemental fresh air ventilation is dependent on the monitored temperature.
7. The FAVC system of claim 6, wherein the duration of the control signal is reduced to zero when the monitored temperature is lower than a first predetermined temperature threshold or higher than a second predetermined temperature threshold.
8. The FAVC system of claim 1, further comprising:
- a fourth electric interface adapted to couple to a thermometer for monitoring temperature of fresh air in a ventilation path coupled to a return path of the air handler; and
- a humidity sensor for monitoring relatively humidity of a return air of the air handler,
- wherein a duration of the control signal for obtaining supplemental fresh air ventilation is dependent on the monitored temperature and relative humidity.
9. The FAVC system of claim 8, wherein the duration of the control signal is reduced by a predetermined proportion for a predetermined set of ranges for the monitored temperature and relative humidity.
10. The FAVC system of claim 1:
- wherein the thermostat controls the air handler to operate in one of a cooling and a heating mode;
- wherein the second input device comprises a first input component and a second input component for independently setting a cooling FAVFR of the air handler when operating in the cooling mode and a heating FAVFR of the air handler when operating in the heating mode;
- wherein the system circuitry is further configured to monitor an operating mode of the air handler via the first electric interface; and
- wherein the second FAVFR comprises one of the cooling FAVFR and the heating FAVFR in correspondence with the monitored operating mode of the air handler.
11. A fresh air ventilation control (FAVC) system, comprising:
- a first input device for setting a first fresh air ventilation flow rate (FAVFR) as a target for a continuous fresh air ventilation;
- a second input device for setting a second FAVFR of an air handler when in operation;
- a third input device for setting a third FAVFR of a first ventilation appliance when in operation;
- a fourth input device for setting a fourth FAVFR of a second ventilation appliance when in operation;
- a first electric interface adapted to couple to the air handler and a thermostat for controlling the air handler;
- a second electric interface adapted to couple to a sensor for monitoring an operation of the first ventilation appliance;
- a third electric interface adapted to couple to the second ventilation appliance;
- a fourth electric interface adapted to couple to a thermometer for monitoring temperature of fresh air in a fresh air ventilation path coupled to a return path of the air handler;
- a fifth electric interface adapted to couple to a motorized damper disposed in the fresh air ventilation path; and
- a system circuitry configured to: monitor operation times of the air handler, the first ventilation appliance, the second ventilation appliance, and a measurement of the thermometer via the first, the second, the third, and the fourth electric interfaces; and control the motorized damper, and/or the air handler, and/or the second ventilation appliance via the first, the third, and the fifth electric interfaces.
12. The FAVC system of claim 11, wherein the system circuitry is further configured to keep the motorized damper open and keep a central fan of the air handler on when the second ventilation appliance is in operation.
13. The FAVC system of claim 11, wherein the system circuity, when configured to control the air handler and the motorized damper and/or the second ventilation appliance, is configured to control air handler and the motorized damper and/or the second ventilation appliance in periodic ventilation cycles.
14. The FAVC system of claim 13, wherein the system circuitry is configured to control the air handler and the motorized damper and/or the second ventilation appliance to meet a predetermined ventilation target in a ventilation cycle.
15. The FAVC system of claim 14, wherein the system circuitry is configured to credit the monitored operation time of the first ventilation appliance in a first ventilation cycle to the predetermined ventilation target of a second ventilation cycle following the first ventilation cycle.
16. The FAVC system of claim 11, further comprising a mode selector for setting the FAVC system into either a normal control mode or an energy saving control mode.
17. The FAVC system of claim 16, wherein, when the FAVC system is set in the energy saving mode, the FAVC system is configured to control the motorized damper and/or the second ventilation appliance and is configured to leave a control of the air handler to the thermostat unless the air handler is idle for a predetermined idle time.
18. The FAVC system of claim 16, wherein, when the FAVC system is set in the normal mode, the FAVC system is configured to control the motorized damper and the second ventilation appliance, and is further configured to control the air handler in conjunction with the thermostat.
19. The FAVC system of claim 11, further comprising a humidity sensor for monitoring a relative humidity of air in the return path of the air handler, wherein a set of constraints based on the monitored relative humidity and the measurement of the thermometer is applied when the FAVC system is configured to control the motorized damper, and/or the air handler, and/or the second ventilation appliance.
20. The FAVC system of claim 11, wherein the system circuitry is further configured to disable control over the motorized damper, the air handler, and the second ventilation appliance when the measurement of the thermometer is above a predefined high temperature threshold or below a predefined low temperature threshold.
Type: Application
Filed: Aug 17, 2018
Publication Date: Feb 28, 2019
Applicant: Field Controls, L.L.C. (Kinston, NC)
Inventors: Eric A. Hokanson (Kinston, NC), Timothy K. Begoske (Brighton, MI), Mark R. Lundberg (Greenville, NC)
Application Number: 16/104,553