# US 2013/0154839 A1 · Hvac controller with hvac system fault detection > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2013/0154839 A1 - Document ID: US20130154839A1 - Status: Published application - Kind: A1 - Application number: 13/325,525 - Filed: 2011-12-14 - Published: 2013-06-20 - Earliest claimed: 2011-12-14 - Assignees: Honeywell International Inc. - Inventors: Eric Barton - Web page: https://patentgrep.com/patent/US20130154839A1 ## CPC - F24F 11/38: Failure diagnosis - F24F 11/30: for purposes related to the operation of the system, e.g. for safety or monitoring - F24F 12/001: {with heat-exchange between supplied and exhausted air} - F24F 11/52: Indication arrangements, e.g. displays - F24F 11/62: characterised by the type of control or by internal processing, e.g. using fuzzy logic, adaptive control or estimation of values - F24F 11/64: using pre-stored data - F24F 11/76: by means responsive to temperature, e.g. bimetal springs - F24F 2110/10: Temperature - F24F 2221/32: preventing human errors during the installation, use or maintenance, e.g. goofy proof - F24F: AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING (removing dirt or fumes from areas where they are produced B08B15/00; vertical ducts for carrying away waste gases from buildings E04F17/02; tops for chimneys or ventilating shafts, terminals for flues F23L17/02) ## Abstract An HVAC controller may be programmed to monitor a current delta T of an HVAC system and to determine a performance level of the HVAC system based, at least in part, on one or more delta T limits stored in the memory of the HVAC controller. The HVAC controller may be further programmed to display or provide a user alert if the performance level falls outside of a normal operating range for the HVAC system. ## Claims ### Claim 1 An HVAC controller configured to control one or more components of an HVAC system, the HVAC controller comprising: a user interface including a display; a memory; and a controller connected to the memory and the user interface, the controller programmed to monitor a delta T of an HVAC system during operation of the HVAC system, and to determine a performance level of the HVAC system based, a least in part, on a delta T limit stored in the memory of the HVAC controller. ### Claim 2 (depends on 1) The HVAC controller according to claim 1, wherein the delta T limit is a maximum delta T limit. ### Claim 3 (depends on 1) The HVAC controller according to claim 1, wherein the delta T limit is a minimum delta T limit. ### Claim 4 (depends on 1) The HVAC controller according to claim 1, wherein the controller is further programmed to determine the performance level of the HVAC system based, at least in part, on a measurement time delay limit stored in the memory of the HVAC controller. ### Claim 5 (depends on 1) The HVAC controller according to claim 1, wherein the controller is configured to determine the performance level of the HVAC system based, at least in part, on a delta T off limit. ### Claim 6 (depends on 1) The HVAC controller according to claim 1, wherein the controller is configured to determine the performance level of the HVAC system using a maximum delta T limit, a minimum delta T limit, and a measurement time delay limit. ### Claim 7 (depends on 1) The HVAC controller according to claim 1, wherein the controller is configured to issue a user alert on the display of the HVAC controller when the performance level of the HVAC system does not meet an expected performance level. ### Claim 8 (depends on 1) The HVAC controller according to claim 1, wherein the controller is configured to compare the monitored delta T to the delta T limit stored in the memory of the HVAC controller when determining the performance level of the HVAC system. ### Claim 9 (depends on 1) The HVAC controller according to claim 1, wherein the delta T limit stored in the memory of the HVAC controller corresponds to a specific stage and operational mode of the HVAC system. ### Claim 10 (depends on 1) The HVAC controller according to claim 1, wherein the controller is configured to record a delta T fault in the memory of the HVAC Controller if the monitored delta T falls outside of the delta T limit, and the delta T fault does not occur during one or more user specified conditions. ### Claim 11 (depends on 10) The HVAC controller according to claim 10, wherein the controller is configured to display a user alert based, in part, on a number of delta T faults recorded by the controller. ### Claim 12 (depends on 1) The HVAC controller according to claim 1, wherein the delta T limit stored in the memory of the HVAC Controller is a user specified delta T limit. ### Claim 13 A method of monitoring a performance of an HVAC system, the HVAC system including one or more HVAC components that are controlled, at least in part, by an HVAC controller having a user interface including a display, a memory, and a controller, the method comprising: the controller monitoring one or more signals from the HVAC system to determine a current delta T value for the HVAC system; and the controller determining a performance level of the HVAC system based, a least in part, on the current delta T value and a delta T limit stored in the memory of the HVAC controller. ### Claim 14 (depends on 13) The method according to claim 13, wherein the delta T limit is received from a user via the user interface of the HVAC controller. ### Claim 15 (depends on 13) The method according to claim 13, further comprising recording a delta T fault in the memory of the controller if the current delta T value falls outside of the delta T limit. ### Claim 16 (depends on 15) The method according to claim 15, further comprising accepting one or more user specified conditions during which delta T faults will be ignored. ### Claim 17 (depends on 13) The method according to claim 13, wherein the delta T limit is a maximum delta T limit. ### Claim 18 (depends on 13) The method according to claim 13, wherein the delta T limit is a minimum delta T limit. ### Claim 19 (depends on 13) The method according to claim 13, wherein the delta T limit is a delta T off limit. ### Claim 20 (depends on 13) The method according to claim 13, further comprising comparing the current delta T value to a maximum delta T limit and a minimum delta T limit stored in the memory of the HVAC controller to determine the performance level of the HVAC system. ### Claim 21 (depends on 20) The method according to claim 20, wherein when the current delta T value is greater than the maximum delta T limit or less than the minimum delta T limit, the performance level of the HVAC system is determined by the controller to be outside of a normal operating range. ### Claim 22 An HVAC controller configured to control one or more components of an HVAC system, the HVAC controller comprising: a user interface including a display; a memory; and a controller connected to the memory and the user interface, the controller programmed to monitor a current delta T of an HVAC system, and to determine a performance level of the HVAC system based, a least in part, on one or more delta T limits stored in the memory of the HVAC controller; the controller further programmed to display on the display of the HVAC controller a user alert if the performance level falls outside of a normal operating range and if the HVAC system is not operating in one or more specified conditions. ### Claim 23 (depends on 22) The HVAC controller of claim 22, wherein the controller displays on the display of the HVAC controller a user alert if the performance level falls outside of a normal operating range for at least a predetermined number of times and if the HVAC system is not operating in one or more specified conditions.