Radio frequency enabled control of environmental zones

A system, apparatus and method for controlling environmental zones in a residence or other building using radio frequency enabled environmental controllers. At least one damper is associated with each of the various zones. From each environmental controller, a command is wirelessly transmitted, where the command includes an environmental control command and a respective unique identifier associated with the environmental controller. The command is received at a zone controller, and each environmental controller is bound with a respective one of the zones using the respective unique identifier associated with the environmental controller. The damper(s) associated with the zone that is bound with the environmental controller associated with the unique identifier from the command are operated in response to the zone controller. Environmental adjustment equipment is operated, which is responsive to the zone controller to execute the environmental control command.

FIELD OF THE INVENTION

This invention relates in general to environmental control systems, and more particularly to a system, apparatus and method for facilitating installation and enhancing flexibility of multi-zone environmental control systems.

BACKGROUND OF THE INVENTION

Commercial and residential environmental control systems generally involve controlling any one or more environmental characteristics such as temperature, humidity, air filtration, and the like. While a single environmental control system may control an entire residence (or other facility), various portions of the residence may not be environmentally controlled to the liking of occupants of those portions of the residence. For example, some rooms in a home may be a longer distance from a central heating, ventilation and air conditioning (HVAC) system, and are not cooled and/or heated as well relative to other rooms closer to the HVAC system. As another example, some rooms may be physically located such that heating or cooling those rooms is more difficult. More particularly, a basement room may require less air conditioning during summer months due to it being underground. Similarly, a south-facing room on an above-ground floor may naturally be warmer than other rooms due to direct sunlight. In yet other situations, occupants of some rooms may simply prefer a higher or lower temperature than occupants of other rooms.

In any of these types of situations, environmental control of particular rooms or other areas of a residence may prove to be difficult. For example, temperature differences in various parts of the home may result in repeated thermostat adjustments, damper adjustments, the use of portable heating/cooling devices, etc. In order to address these issues, homes or other facilities may use “zoning” to allow for independent control of each of the various established zones. For example, a home may be divided into two different zones, where each zone is controlled by its own thermostat or a thermostat that is configured to independently control each of the zones.

However, dividing homes or other facilities into zones and providing separate thermostats for each zone requires additional wiring. This may be particularly burdensome in residences where a single-zone system is to be upgraded to a multi-zone system. Invasive wiring of thermostats and zone control systems into existing walls and other structures can be expensive and inconvenient for the homeowner. For example, multiple thermostats may need to be wired to a zone control panel, which in turn is wired to the HVAC or other environmental control system.

Accordingly, there is a need in the environmental control industry for a manner of alleviating the cost and inconvenience of installing and utilizing multi-zone environmental control systems. The present invention fulfills these and other needs, and offers other advantages over prior art approaches.

SUMMARY OF THE INVENTION

To overcome limitations in the prior art described above, and to overcome other limitations that will become apparent upon reading and understanding the present specification, the present invention discloses a system, apparatus and method for controlling environmental zones in a residence or other building using radio frequency enabled environmental controllers

In accordance with one embodiment of the invention, a method is provided for controlling environmental conditions in a plurality of zones using a corresponding plurality of environmental controllers. The method involves associating at least one respective damper with each of the plurality of zones. From each environmental controller, a command is transmitted via unidirectional wireless communication, where the command includes an environmental control command and a respective unique identifier associated with the environmental controller. The command is received at a zone controller, and each environmental controller is bound with a respective one of the zones using the respective unique identifier associated with the environmental controller. The method further involves operating the damper(s) associated with the zone that is bound with the environmental controller that is associated with the unique identifier from the command, where the damper(s) is operated in response to the zone controller. Environmental adjustment equipment is operated, which is responsive to the zone controller to execute the environmental control command.

According to more particular embodiments of such a method, each environmental controller may be positioned within the zone that is bound with the environmental controller. In another embodiment, binding each environmental controller involves performing such binding in connection with an installation procedure. In another particular embodiment, the command is transmitted using a Manchester encoding with binary amplitude modulation at a center radio frequency of approximately 345 MHz, and where the command includes a preamble. In yet another particular embodiment, the command is transmitted more than once to increase the probability that the zone controller receives the command. In other embodiments, the command is transmitted in response to user input, environmental conditions at the environmental controller deviating from and/or returning to desired conditions, the expiration of a predetermined time interval relative to a previous transmission from the environmental controller, etc.

In still other particular embodiments of such a method, the command may include a cyclic redundancy check to detect corruption of the command. Such a method may further involve checking the command received by the zone controller using the cyclic redundancy check, and if corruption of the command is detected, the command may be discarded before binding each environmental controller, operating the damper(s), and directing the environmental adjustment equipment. Further, a respective time interval may be associated with each of the zones, where the command is associated with the time interval of the zone bound to the environmental controller that is associated with the unique identifier from the command. If corruption of the command is not detected, the method of such an embodiment involves starting the time interval associated with the command in connection with the receiving of the command. Otherwise, each time interval exceeding a predetermined limit may be treated as receiving a command having the environmental control command of an idle command.

In another particular embodiment, binding each environmental controller involves further comprises, for each zone, operating a respective binding switch associated with the zone. An association is established between the zone and the environmental controller that is associated with the unique identifier from the command, thereby binding the environmental controller that transmits the command with the zone. Further, a visual indication may be initiated after operating the respective binding switch, and this visual indication may be terminated after establishing the association.

In another embodiment of the method, a value of the environmental control command includes any one or more of a heat command, a cool command, a fan command, an auxiliary heat command, an emergency heat command, an auxiliary cool command, a humidity control command, an extra command, an idle command, an error command, an air quality alarm command, an air quality venting command, a motion detection command, or a service alarm command. In one embodiment the damper(s) is opened in connection with the operating the damper(s) in response to the environmental control command having the value that is not the idle command, and the damper(s) is closed in connection with operating the damper(s) in response to the idle command. In another particular embodiment, directing the environmental adjustment equipment involves operating at least one of a heat relay, a cool relay, a fan relay, an auxiliary heat relay, an emergency heat relay, an auxiliary cool relay, a humidity control relay, an extra relay, a first stage pump relay, a second stage pump relay, or a changeover valve relay.

In still other embodiments of such a method, the zone controller may resolve a conflict between the command received from a first one of the environmental controllers and the command received from a second one of the environmental controllers, by sequentially directing the environmental adjustment equipment to execute the command received from the first one of the environmental controllers and the command received from the second one of the environmental controllers.

In accordance with another embodiment of the invention, a zone controller is provided, and is arranged to control the environmental conditions in a plurality of environmental zones. The zone controller includes a radio frequency receiver adapted to receive commands transmitted from the plurality of zones, where each command includes an environmental control command and a unique identifier. A plurality of binding switches is provided, where each is adapted to bind a respective one of the zones with a respective one of the unique identifiers. The zone controller includes a plurality of damper output ports, each arranged to operate at least one respective damper associated with a respective one of the zones. An equipment output port is arranged to operate environmental adjustment equipment. The zone controller further includes a zone sequencer adapted for each command to control the equipment output port based on the environmental control command, and to control the plurality of damper output ports based on the environmental control command and on the zone bound to the unique identifier.

In a more particular embodiment, the zone controller includes an error check circuit adapted to detect corruption of each command, and to discard each command with detected corruption. In another embodiment, a visual indicator is arranged to indicate that a binding operation is in progress, where the binding operation is initiated by activating at least one of the binding switches. In another embodiment, the zone sequencer includes at least one relay coupled to the equipment output port, where the relay(s) comprises any of a heat relay, a cool relay, a fan relay, an auxiliary heat relay, an emergency heat relay, an auxiliary cool relay, a humidity control relay, an extra relay, a first stage pump relay, a second stage pump relay, or a changeover valve relay.

In another embodiment, the zone controller includes at least one controller input port, where each controller input port associated with a respective one of the zones, where each controller input port is arranged to receive at least one environmental control signal. In such an embodiment, the zone sequencer is further adapted for each controller input port to control the equipment output port based on the environmental control signal(s), and to control the damper output ports based on the environmental control signal(s) and on the zone associated with the controller input port.

In another embodiment, an HVAC system is provided, which is arranged to control the environmental conditions in a plurality of zones. The system includes a plurality of wireless environmental controllers, an HVAC subsystem, a plurality of dampers, and a zone controller. Each of the plurality of wireless environmental controllers is adapted to transmit commands, where each command includes an environmental control command and a unique identifier for the wireless environmental controller transmitting the command. Each of the zones is respectively associated with at least one of the dampers. The zone controller includes a radio frequency receiver adapted to receive each command, a plurality of binding switches each adapted to bind a respective one of the zones with a respective one of the unique identifiers, and a zone sequencer. The zone sequencer is adapted for each command to control the HVAC subsystem based on the environmental control command, and to control the plurality of dampers based on the environmental control command and on the zone bound to the unique identifier.

DETAILED DESCRIPTION OF THE INVENTION

Generally, the present invention provides control of environmental zones in a residence or other building using radio frequency enabled environmental controllers. Environmental controllers such as thermostats are equipped with wireless transmitters. Commands issued from the thermostats include respective unique identifiers associated with its respective thermostat, where the unique identifier is used to bind the particular thermostat with a respective zone in a multi-zone environment. A zone controller capable of wirelessly receiving these commands controls HVAC equipment such as dampers in the zone associated with the transmitting thermostat. In this manner, environmental control of various zones may be effected using wireless means, thus obviating the need to introduce wiring between the thermostats and zone controller.

FIG. 1is a block diagram of an embodiment for control of a plurality of environmental zones102104106by radio frequency enabled environmental controllers108110112. Each zone102104106is typically a room or group of rooms in a building such as a residence or office building. Each zone102104106has a respective environmental controller108110112that is typically physically located within the zone. Environmental controller108is located within zone-1102, environmental controller110is located within zone-2104, and environmental controller112is located within zone-N106.

Each environmental controller108110112detects the environmental conditions local to the respective zone102104106and transmits commands to adjust the local environment to the zone controller114. For example, a heat command is transmitted by the environmental controller108for a zone102when the temperature in the zone102falls below an acceptable level. For this example when the temperature in zone102recovers to an acceptable level the environmental controller108transmits a command to end the heating cycle for zone102. Example environmental conditions that may be controlled are temperature, humidity, and air quality including carbon monoxide concentration. The commands are sent from each environmental controller108110112to the zone controller114via a radio frequency transmission. The radio frequency transmissions are unidirectional from each environmental controller108110112to the zone controller114. There are no transmissions from the zone controller114to any of the environmental controllers108110112.

The zone controller114directs the opening and closing of dampers116118120in response to the commands received from the environmental controllers108110112. The zone controller114and the dampers116118120are typically located near the heating, ventilation and air conditioning (HVAC) system128. Each damper116118120is associated with a respective environmental zone102104106by a respective duct or ducts122124126. Damper116is associated with zone-1by duct122, damper118is associated with zone-2104by duct124, and damper120is associated with zone-N106by duct126. For example, when environmental controller108in zone-1102commands for heat delivery, then damper116is opened by the zone controller114so that heat can be delivered from the HVAC system128to zone-1102. For this example the other dampers118120may be open or closed depending upon whether environmental controllers110112are also calling for heat delivery.

The zone controller114resolves any conflicts between the environmental controllers108110112. For example, environmental controller108may be transmitting heat commands while environmental controller110is transmitting cool commands. This may happen for example on a cool sunny day when the windows of zone-2104are receiving abundant sunshine while zone-1102is shaded. Typically the HVAC system128cannot heat and cool simultaneously. The zone controller114resolves conflicting commands by sequentially performing the conflicting commands. In the absence of conflicts the environmental control decisions are made by the environmental controllers108110112and not by the zone controller114. The zone controller114resolves conflicts and also may direct the changeover between conflicting commands, such as a time delay required by the HVAC system128when switching from heating to cooling. The zone controller114may have additional timers such as a timer that activates emergency heat when the duration of a heating cycle exceeds a specified limit.

Using radio frequency enabled environmental controllers108110112and dampers116118120located near the HVAC system128permits adding environmental zones102104106to retrofit an existing HVAC system128using the existing ducts122124126and wiring. Ducts122124126and wiring within the living space are difficult to modify, but the HVAC system128is typically located outside of the living space where modifications may be made. For the retrofit application the required duct122124126and wiring modifications are localized to the vicinity of the HVAC system128when radio frequency enabled environmental controllers108110112are used. For new construction the radio frequency enabled environmental controllers108110112simplify the required wiring. The radio frequency environmental controllers108110112also permit a mobile location for each of the environmental controllers108110112within the corresponding zone102104106for both retrofit applications and new construction.

In one embodiment, the dampers116118120when open allow forced air heating or air conditioning to be delivered from the HVAC system128via ducts122124126to the zones102104106. In another embodiment, the dampers116118120are valves in a hot water (or other fluid) HVAC system128with the ducts122124126being pipes that circulate the hot water/fluid to radiators in the respective zones102104106.

FIG. 2is a system diagram of a representative embodiment for control of environmental zones202204206and a HVAC system208by hardwired environmental controller210and radio frequency enabled environmental controllers212214. In such an embodiment, the environmental zone-1202is controlled by a hardwired environmental controller210. This may be useful in a retrofit application where there is an existing environmental controller that is in an appropriate location for one of the zones. In general, each zone202204206may have an environmental controller that is either hardwired or radio frequency enabled.

The line transformer216provides power to the HVAC system208and the zone controller218. Typically the line transformer216provides power of 24 volts alternating current. For some systems multiple transformers are used to provide the function of the line transformer216such as separate transformers for the zone controller218, the heating portion of the HVAC system208, and the cooling portion of the HVAC system208. The zone controller218controls the power to open and close the dampers220222224. The zone controller218may also provide power to the hardwired environmental controller210. Alternatively, the hardwired environmental controller210may be powered by an independent power supply such as a thermocouple or a battery, or the hardwired environmental controller210may be may be an electromechanical controller that does not require power for operation. The radio frequency enabled environmental controllers212214are typically powered by respective supplies such as a local line transformer, a battery, a solar cell, or a combination thereof.

The HVAC system208shows a representative embodiment of a heat pump installation with two stages and emergency heat. The zone controller218directs the HVAC system208in response to commands received from the environmental controllers210212214in the respective environmental zones202204206. When the zone controller218receives a heat command from one or more of the environmental controllers210212214, the zone controller218puts the changeover valve226into heat mode and then activates the pump relay228. The zone controller218may need to delay the beginning of this heating cycle when a previous cooling or heating cycle was recently completed. The zone controller218also opens the dampers220222224corresponding to the zones202204206currently calling for heat. When the zone controller218receives an auxiliary heat command from one or more of the environmental controllers210212214, the zone controller218additionally activates the second stage compressor relay230to provide additional heat. When the zone controller218detects that the duration of a heating cycle has exceeded a specified time limit without restoring environmental conditions in one or more zones202204206, then the zone controller218may also activate the emergency heat relay232to provide extra additional heat such as an electrical heating element. Alternatively, when the zone controller218receives an emergency heat command from one or more of the environmental controllers210212214, the zone controller may activate the emergency heat relay232.

When the zone controller218receives a cool command from one or more of the environmental controllers210212214, the zone controller218puts the changeover valve226into cool mode and then activates the pump relay228. The zone controller218may need to delay the beginning of this cooling cycle when a previous heating or cooling cycle was recently completed. The zone controller218also opens the dampers220222224corresponding to the zones202204206calling for cooling. When the zone controller218receives an auxiliary cool command from one or more of the environmental controllers210212214, the zone controller218additionally activates the second stage compressor relay230to provide additional cooling. When the zone controller218receives a fan command from one or more of the environmental controllers210212214, the zone controller218activates the fan relay234. The zone controller218also opens the dampers220222224corresponding to the zones202204206calling for the fan.

When the zone controller218receives an idle command from one of the environmental controllers210212214the zone controller218closes the one of the dampers220222224corresponding to the zone of this environmental controller. If this damper closing causes all dampers220222224to be closed, before closing this damper the zone controller218completes the current cycle by deactivating all relays226228230232234. The zone controller218also manages conflicts between the commands received from the various environmental controllers210212214as previously discussed.

FIG. 3is a diagram of an example command packet300transmitted by a radio frequency environmental controller. The command packet300includes the fields of a preamble field302, an identifier field304containing a unique serial number, a command field306, and a cyclic redundancy check (CRC) field308. The fields304306308can appear in any order in the command packet300although the CRC field308is typically the last field in the command packet300. The command packet300may be transmitted with a Manchester encoding using binary amplitude modulation at a center transmission frequency of 345 MHz.

The preamble field302announces the beginning of the packet300. The preamble field302is transmitted at the beginning of every command packet300. The same value is used for every preamble field302. A receiver of the packet300uses the preamble field302to synchronize the reception of the packet300. For one example the preamble field302is 16 bits long.

The identifier field304contains a unique serial number. Each radio frequency environmental controller is given a serial number during manufacture. The serial numbers may be assigned to environmental controllers in a pseudo-random order. The manufacturer unilaterally attempts to ensure that only one radio frequency environmental controller using the same encoding, modulation, and center transmission frequency has a particular serial number. The serial number is not necessarily unique among all radio frequency environmental controllers or radio frequency transmitters. The identifier field304contains the serial number of the radio frequency environmental controller transmitting the command packet300. The identifier field304in the packet300allows the source of the packet300to be determined. One use for the unique identifier field304is to prevent interference from an independently installed environmental controller in a neighboring building. In one embodiment, the identifier field304is 24 bits in length.

The command field306may be composed of individual command bits. The command field306for this example is 8 bits long with up to 8 possible commands. These 8 commands are the heat command310, the auxiliary heat command312, the emergency heat command314, the humidity command316, the cool command318, the auxiliary cool command320, the fan command322, and the extra command324. Not all 8 commands may be implemented in a particular model of radio frequency environmental controller. An idle command has no command bits set. An idle command is transmitted by an environmental controller for a zone while the zone has an acceptable environmental condition.

It will be appreciated that alternative command encodings may be used and the command306may have more or fewer than 8 bits. For example, simultaneously sending a heat command320, the cool command318, and the fan command322may indicate an error command. In another embodiment, rather than having individual command on/off flag bits310,312,314,316,318,320,322, and324, the command306could be encoded such that an operational code is defined for some or all values of the entire command306. As a more particular example, a command306having 8 bits results in as many as 256 operational codes, potentially allowing a greater number of specific commands. Other such commands may include, for example, an air quality alarm or venting operation when smoke or carbon monoxide is detected by the environmental controller, a motion detector on the environmental controller to activate occupied zone environmental control that may be different from the unoccupied zone environmental control, and a service alarm from the environmental controller that is automatically generated or generated in response to user input and may cause an alarm or a telephone call to summon service such as a maintenance service, police, or an ambulance.

A receiver of a command packet300may receive a command packet300that has been corrupted. The corruption may be caused by interference from other radio frequency transmitters in the vicinity. The CRC field308allows corrupted command packets300to be detected by the receiver. The CRC field308is calculated over the command field306and typically also the identifier field304, but not the preamble field302. A receiver of a command packet300recalculates the CRC and compares the recalculated CRC with the CRC308received in the packet. When these CRC differ, a receiver typically discards the corrupted packet. To help ensure that an individual command is not lost, one embodiment involves transmitting each command packet300multiple times every time a command update is needed. For one example the CRC field308is 16 bits long.

FIG. 4is a flow diagram of an example process for binding a radio frequency environmental controller to a zone. The binding process forms an association between the serial number of an environmental controller and the zone corresponding to the environmental controller. The binding process is repeated for each environmental controller.

The binding process typically begins with the user or installer bringing the radio frequency environmental controllers to the location in the building of the zone controller. All environmental controllers are powered off. The user closes a binding switch for a particular zone number on the zone controller at step402and selects an environmental controller to correspond to the zone. Typically the user writes the zone number and the zone name on a label affixed to the back of the selected environmental controller. An example zone name is living room. The zone number is determined by the binding switch that was closed. The zone name is determined by the damper coupled to that zone number and the environmental zone associated with that damper by the ducts. At step404the zone controller provides feedback that binding is in process by starting the blinking of a LED corresponding to the zone number.

At step406the user powers on the selected environmental controller to cause it to issue a command packet. Typically the environmental controller transmits a command packet immediately after power on and this packet is successfully received by the zone controller. Occasionally additional packets are needed and the user may cause additional packets to be transmitted by the environmental controller by toggling the fan setting on the environmental controller. At step408the zone controller receives a command packet that passes the CRC check.

At step410the identifier is extracted from the command packet received by the zone controller. At step412the extracted identifier is compared with identifiers from any existing bindings. When the extracted identifier matches an existing binding the extracted identifier is ignored by returning to step406. This ensures that there is an environmental controller for each zone and allows the previously bound environmental controllers to remain powered on during the binding of additional environmental controllers. When the extracted identifier does not match any existing binding the process proceeds to step414.

At step414the zone controller binds the new extracted identifier to the zone number and thereby the associated environmental zone. A command packet received thereafter with this identifier is processed as a command for the zone of the binding. The zone controller provides feedback that the binding is complete for the environmental controller by stopping the blinking of the LED corresponding to the zone number at step416. After a binding is completed, the binding switch for the zone remains in the closed position.

After all bindings are complete the user typically returns the environmental controllers to their designated environmental zones. The user may verify the bindings by toggling the fan command on each environmental controller and checking fan operation in each environmental zone. If it is determined that an incorrect binding was made for a zone, the binding switch for that zone number is opened causing the zone controller to erase the binding. A new binding may then be made for the zone.

FIG. 5is a block diagram of a representative embodiment of a radio frequency environmental controller502with a thermostat function. A humidistat function can similarly be provided. The environmental controller502transmits command packets to a receiver via antenna504. The environmental controller502is only a transmitter. The environmental controller502contains no circuitry to receive packets. The environmental controller502is located within an environmental zone. While command packets are unidirectional transmissions, control of the environmental zone is closed loop control since feedback is provided by the commanded adjustments to the environmental conditions in the zone.

An analog to digital comparator506is used to translate an analog temperature reading from the thermistor508into a digital format. The comparator506is used to measure the RC time constant of the thermistor508and a capacitor. The RC time constant is measured by counting the number of clock cycles needed to charge this RC circuit to a trip point set by a resistor divider. The RC time constant of the precision calibration resistor510and the same capacitor is similarly measured. The calibration resistor510is selected to have a resistance equal to the thermistor508at a center temperature near the middle of the desired measurement range. The difference between the two measurement counts provides a digital value for the difference between the center temperature and the environmental temperature. To reduce power consumption the temperature measurement is performed intermittently and the measurement circuits including the comparator506are powered down between measurements.

The microcontroller512controls the environmental controller502via programs and data stored in the RAM/ROM514. A clock generator516provides the clock for the microcontroller512. This clock is a low frequency clock to minimize power consumption by the microcontroller512and associated components. A user interface is provided by the keypad518and liquid crystal display (LCD)520. The keypad allows the user to specify the setpoints for the humidity, the regular and auxiliary cooling, and the regular, auxiliary, and emergency heating. The keypad allows the user to turn the fan on and off.

Command packets are assembled by the microcontroller512to adjust the environmental conditions in the zone as specified by the user settings. The command packets are transmitted by the radio frequency transmitter522. To reduce power consumption packets are sent only when command updates are needed in response to changing environmental conditions, user input is received, or at least every 10 minutes. Between packets the transmitter522is powered down to further conserve power.

The aggressive power management allows the environmental controller502to be powered for more than a year in a typical application using ordinary alkaline AA batteries.

FIG. 6is a connection diagram for one embodiment of a zone controller with three zones. The illustrated zone controller includes an antenna602, a radio frequency receiver604, and a zone sequencer606. The receiver604and the zone sequencer606are typically separated to allow the zones to be individually controlled by either a hardwired environmental controller or a radio frequency enabled environmental controller. For example to use a hardwired environmental controller for zone-1, the connections shown for the zone-1environmental controller connection block608on the zone sequencer606are replaced with connections to the hardwired environmental controller and the terminals of the zone-1connection block610on the receiver604are unconnected. For this example the connection blocks612614on the zone sequencer606respectively remain connected to the connector blocks616618on the receiver604.

The receiver604decodes command packets received from the environmental controllers via the antenna602. Each command packet contains an identifier field containing the serial number of the environmental controller that transmitted the packet. The bind switches620and zone LEDs622are used during installation to bind the environmental controllers to the zones. To bind an environmental controller to a particular zone, the bind switch for that zone is closed by the installer. The receiver604responds by starting the blinking of a corresponding zone LED. The installer powers on the environmental controller causing the environmental controller to send a packet. The receiver604receives the packet and binds the identifier in the packet to the zone, and stops the blinking of the corresponding zone LED. Thereafter whenever a packet is received with the bound identifier, the command is routed to the output connector block of the connector blocks610616618that corresponds to the bound zone.

The connector blocks610616618on the receiver604and the connector blocks608612614on the zone sequencer606contain terminals labeled R, C, W1, Y1, G, W2, and Y2for power624, ground626, heat628, cool630, fan632, auxiliary heat634, and auxiliary cool636respectively. Emergency heat, humidity, and extra commands are not supported by this embodiment of the receiver604or by this embodiment of the zone sequencer606. The zone sequencer606can be enabled to generate a call for emergency heat in response to exceeding a specified time limit for the duration of a heating cycle.

The receiver604checks that a packet is received from each environmental controller at least once every 30 minutes. The receiver604handles the case of no packet received from an environmental controller for 30 minutes as an implied idle command from the environmental controller.

The mode switches638configure the operation of the zone sequencer606. The mode switches638allow the zone sequencer606to support various HVAC systems such as a heat pump and gas burner with air conditioner. The status LEDs640indicate the current command being executed by the zone sequencer606or changeover purging. Some HVAC systems require a changeover purging period between conflicting commands. The status LEDs640also indicate the zone or zones with open dampers.

The three dampers642644646are respectively connected to the damper connectors648650652. The zone sequencer606supports dampers of type power open and power close642, power open and spring close644, and spring open and power close646.

FIG. 7is a diagram showing an example of unidirectional transmission of command packet702from an environmental controller704to a zone controller706. The environmental controller704in this example is designed to be battery powered, allowing the environmental controller704to have a flexible or mobile location within zone-1708. A battery powered environmental controller704requires a careful design to minimize power consumption, especially if ordinary alkaline batteries are used. A design with aggressive power management has the majority of the power consumed by the radio frequency communication circuits. This is true even when the environmental controller704has a complex control function such as multiple setpoints over a seven day schedule.

To reduce the power consumption of the radio frequency communication circuits the environmental controller704does not have a radio frequency receiver. The environmental controller704only transmits packets702. The transmitter in environmental controller704is powered down between packets702to further conserve power. Packets702are sent only when command updates are needed in response to changing environmental conditions, user input is received, or 10 minutes have elapsed since the last packet702was transmitted. To conserve power the idle command may be transmitted only near the beginning of a time period of acceptable conditions in the environmental zone708, since the receiver716typically treats not receiving a packet702for 30 minutes as an implied idle command for the zone708. In additional to transmitting packets702only intermittently, the length of the packet702is minimized to conserve power.

Putting the results of control decision in the command packet702instead of the data that is used to make these control decisions, such as the current temperature, produces shorter packets702that need to be sent less frequently. As an example, a drop in temperature does not necessarily result in a control decision to call for heat. Overall power consumption of the environmental controller704is reduced by using these command packets702even though the environmental controller704may need to have more complex control logic.

For this example the temperature in zone-1708has just dropped below the minimum desired temperature. The environmental controller704makes the control decision to generate a heat command. The environmental controller704transmits the heat command packet702to the zone controller706via antenna710. The command field712of the packet702contains the value for a heat command. The environmental controller identifier field714contains the identifier for the environmental controller704in zone-1708. The receiver716in the zone controller706receives this command packet702via the antenna718. For this example the command packet702passes the CRC check. The receiver716recognizes from the identifier field714that this packet702is from zone-1708. The receiver716sends the heat command to the zone-1input of the zone sequencer720of the zone controller706. Currently for this example the zone sequencer720has no conflicts such as another zone calling for cooling. Currently for this example the zone sequencer720is not imposing a changeover delay from a previous heating or cooling cycle. Since there are currently no conflicts and no changeover delay, the zone sequencer720executes the command by signaling the HVAC system722to generate heat and opening the zone-1damper724.

FIG. 8is a flow diagram of a representative embodiment of a process for control of a plurality of environmental zones. The process begins at step802with the establishment of environmental zones by the installation of a damper for each zone. The dampers are typically located near the HVAC system. The installation can be either a retrofit application or new construction. Installation continues at step804by binding an environmental controller with each zone using the serial number of the environmental controller as a unique identifier for the environmental controller. The environmental controllers are located in the corresponding zone.

At step806during normal operation, an environmental controller transmits a command packet containing a command and the serial number of the environmental controller as a unique identifier for the environmental controller. At step808this command packet is received by the zone controller. At step810the zone controller operates the damper corresponding to the zone that was bound to the identifier for the environmental controller. At step812the zone controller directs the HVAC system to perform the command contained in the command packet.