Remote HVAC monitoring and diagnosis

1. A monitoring system for a heating, ventilation, and air conditioning (HVAC) system of a building, the monitoring system comprising: a monitoring device installed at the building, wherein the monitoring device is configured to (i) measure an aggregate current supplied to a plurality of components of the HVAC system over a series of time periods, (ii) process the aggregate current data for each time period to create a frequency domain representation for each time period, and (iii) transmit, for each time period, the frequency domain representation based on the measured aggregate current; and

a server located remotely from the building, wherein the server is configured to (i) receive the transmitted frequency domain representations, (ii) based on the received frequency domain representations, assess whether a failure has occurred in a first component of the plurality of components of the HVAC system, (iii) based on the received frequency domain representations, assess whether a failure has occurred in a second component of the plurality of components of the HVAC system, (iv) generate an alert in response to determining presence of a fault of either the first component or the second component, and (v) send the alert to at least one of (a) an owner of the building and (b) an HVAC contractor.

2. The monitoring system of claim 1 wherein the server is configured to identify times corresponding to transitions in an operational sequence of the HVAC system based on the transmitted frequency domain representations.

3. The monitoring system of claim 1 wherein the server is configured to determine whether the failure has occurred in the first component by comparing the frequency domain representations to baseline data.

4. The monitoring system of claim 3 wherein the server is configured to adapt the baseline data based on normal operation of the HVAC system.

5. The monitoring system of claim 1 wherein the monitoring device is configured to determine a single time domain current value for each time period and transmit the determined single time domain current value to the server for each time period without transmitting individual current samples to the server.

6. The monitoring system of claim 1 wherein the monitoring device is configured to record control signals from a thermostat and transmit information based on the control signals to the server.

7. The monitoring system of claim 1 wherein:

the monitoring device is located in close proximity to an air handler unit of the HVAC system;

the monitoring system further comprises a second monitoring device located in close proximity to a second enclosure of the HVAC system; and

the second enclosure includes at least one of a compressor and a heat pump heat exchanger.

8. The monitoring system of claim 7 wherein the second monitoring device is configured to:

measure a second aggregate current supplied to a plurality of components of the second enclosure; and

transmit current data based on the measured second aggregate current to the server via the monitoring device.

9. The monitoring system of claim 1 wherein the server is configured to:

selectively predict an impending failure of the first component based on the received frequency domain representations;

selectively predict an impending failure of the second component based on the received frequency domain representations; and

generate an alert in response to prediction of impending failure.

10. A method of monitoring a heating, ventilation, and air conditioning (HVAC) system of a building, the method comprising:

using a monitoring device installed at the building, measuring an aggregate current supplied to a plurality of components of the HVAC system over a series of time periods and processing the measured aggregate current for each time period to create a frequency domain representation for each time period;

transmitting, for each time period, the frequency domain representations based on the measured aggregate current to a server located remotely from the building;

at the server, assessing whether a failure has occurred in a first component of the plurality of components of the HVAC system based on the received frequency domain representations;

at the server, assessing whether a failure has occurred in a second component of the plurality of components of the HVAC system based on the received frequency domain representations;

generating an alert in response to determining presence of a fault of either the first component or the second component; and

sending the alert to at least one of (i) an owner of the building and (ii) an HVAC contractor.

11. The method of claim 10 further comprising:

identifying times corresponding to transitions in an operational sequence of the HVAC system based on the frequency domain representations; and

analyzing the frequency domain representations around the identified times.

12. The method of claim 10 further comprising determining whether the failure has occurred in the first component by comparing the frequency domain representations to baseline data.

13. The method of claim 12 further comprising adapting the baseline data based on normal operation of the HVAC system.

14. The method of claim 10 comprising:

determining a single time domain current value for each time period; and

transmitting the determined single time domain current value to the server for each time period without transmitting individual current samples to the server.

15. The method of claim 10 further comprising:

transmitting a frame of information to the server for each of the time periods,

wherein, for a first period of the time periods, the corresponding frame of information (i) includes a single time domain value corresponding to the aggregate current during the first period, (ii) includes the frequency domain representation of the aggregate current during the first period, and (iii) does not include individual samples of the aggregate current.

16. The method of claim 10 further comprising:

recording control signals from a thermostat; and

transmitting information based on the control signals to the server.

17. The method of claim 10 wherein the monitoring device is located in close proximity to an air handler unit of the HVAC system, and wherein the method further comprises:

measuring a second aggregate current supplied to a plurality of components of a second enclosure of the HVAC system using a second monitoring device located in close proximity to the second enclosure, wherein the second enclosure includes at least one of a compressor and a heat pump heat exchanger; and

transmitting current data based on the measured second aggregate current to the server.

18. The method of claim 10 further comprising:

selectively predicting an impending failure of the first component based on the received frequency domain representations;

selectively predicting an impending failure of the second component based on the received frequency domain representations; and

generating an alert in response to prediction of impending failure.