# US 11,029,055 B2 · Fan coil thermostat with fan ramping > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,029,055 B2 - Document ID: US11029055B2 - Status: Granted - Kind: B2 - Application number: 16/745,591 - Filed: 2020-01-17 - Published: 2020-05-21 - Granted: 2021-06-08 - Earliest claimed: 2007-08-03 - Assignees: Honeywell International Inc. - Applicants: Honeywell International Inc. - Inventors: Daniel J. Sullivan; Levi H. Geadelmann; Paul Wacker - Web page: https://patentgrep.com/patent/US11029055B2 ## CPC - F24F 11/77: by controlling the speed of ventilators - F24F 1/0007: Indoor units, e.g. fan coil units (self-contained units F24F1/02) - F24F 1/0018: characterised by fans (with secondary air induced by injector action of the primary air F24F1/01) - F24F 11/30: for purposes related to the operation of the system, e.g. for safety or monitoring - F24F 11/46: Improving electric energy efficiency or saving - F24F 11/523: for displaying temperature data - 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 11/63: Electronic processing - F24F 11/76: by means responsive to temperature, e.g. bimetal springs - F24F 11/83: by controlling the supply of heat-exchange fluids to heat-exchangers - F24F 11/84: using valves - G05B 19/048: Monitoring; Safety - F24F 11/52: Indication arrangements, e.g. displays - F24F 11/65: for selecting an operating mode - F24F 2110/10: Temperature - F24F 2140/60: Energy consumption - G05B 2219/2614: HVAC, heating, ventillation, climate control - Y02B 30/70: Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating - 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) - G05B: CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS (systems for controlling or regulating non-electric variables G05D; systems for regulating electric or magnetic variables G05F; control devices or systems insofar as characterised by mechanical features only G05G) - Y02B: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS ## Abstract Fan coil thermostats can provide energy savings by, for example, operating a fan coil system more efficiently. Fan coil systems employing such a fan coil thermostat may be more energy efficient. A fan coil system may include a fan coil that is configured for fluid communication with a source of heated fluid and/or a source of cooled fluid, a valve that controls fluid flow through the fan coil and a fan that blows air across the fan coil. The fan coil thermostat may include a controller that implements a control algorithm that calculates an error percentage value relating to a temperature difference between the current temperature and the temperature set point. The error percentage value may include a proportional term related to the temperature difference and an integral term related to the temperature difference. The controller may regulate the fan speed in accordance with the calculated error percentage. ## Claims ### Claim 1 A method of operating a fan coil system comprising a fan coil and a fan adapted to blow air across the fan coil, the fan having a plurality of fan speeds within a fan throttle range, the method comprising: obtaining a current temperature value from a temperature sensor; determining a fan speed control signal that is based at least in part on a temperature difference between the current temperature value and a temperature set point and on a measure related to how long the temperature difference has persisted; operating the fan at a first fan speed when the fan speed control signal is below a first threshold; operating the fan at a second fan speed above the first fan speed when the fan speed control signal is above the first threshold but below a second threshold; and operating the fan at a third fan speed above the second fan speed when the fan speed control signal is above the second threshold. ### Claim 2 (depends on 1) The method of claim 1, wherein the third fan speed is a maximum fan speed of the fan coil system. ### Claim 3 (depends on 1) The method of claim 1, wherein the first fan speed is a low fan speed, the second fan speed is an intermediate fan speed and the third fan speed is a maximum fan speed. ### Claim 4 (depends on 1) The method of claim 1, further comprising: implementing hysteresis when switching between the first fan speed and the second fan speed. ### Claim 5 (depends on 4) The method of claim 4, further comprising: implementing hysteresis when switching between the second fan speed and the third fan speed. ### Claim 6 (depends on 1) The method of claim 1, wherein the measure of how long the temperature difference has persisted is determined based at least in part by an integral of the temperature difference over time. ### Claim 7 (depends on 1) The method of claim 1, where the fan throttle range is established such that the fan operates at a maximum fan speed when the fan speed control signal is above the second threshold. ### Claim 8 (depends on 1) The method of claim 1, wherein the fan coil accommodates fluid flow therethrough. ### Claim 9 A method of operating a fan coil system comprising a fan coil and a fan adapted to blow air across the fan coil, the fan having a plurality of fan speeds within a fan throttle range, the method comprising: obtaining a current temperature value from a temperature sensor; determining a fan speed control signal for controlling the speed of the fan, the fan speed control signal free from a pre-programmed mapping between a plurality of pre-programmed fan speeds and a plurality of temperature difference subranges between the current temperature value and a temperature set point; operating the fan at a first fan speed when the fan speed control signal is below a first threshold; operating the fan at a second fan speed above the first fan speed when the fan speed control signal is above the first threshold but below a second threshold; and operating the fan at a third fan speed above the second fan speed when the fan speed control signal is above the second threshold. ### Claim 10 (depends on 9) The method of claim 9, wherein the fan speed control signal is determined based at least in part on a temperature difference between the current temperature value and the temperature set point as well as a measure related to how long the temperature difference has persisted. ### Claim 11 (depends on 10) The method of claim 10, wherein the measure of how long the temperature difference has persisted is determined based at least in part by an integral of the temperature difference over time. ### Claim 12 (depends on 9) The method of claim 9, wherein the third fan speed is a maximum fan speed of the fan coil system. ### Claim 13 (depends on 9) The method of claim 9, wherein the first fan speed is a low fan speed, the second fan speed is an intermediate fan speed and the third fan speed is a maximum fan speed. ### Claim 14 (depends on 9) The method of claim 9, further comprising: implementing hysteresis when switching between the first fan speed and the second fan speed. ### Claim 15 (depends on 14) The method of claim 14, further comprising: implementing hysteresis when switching between the second fan speed and the third fan speed.