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US-12624977-B1 - Simple airflow measurement method for HVAC systems

US12624977B1US 12624977 B1US12624977 B1US 12624977B1US-12624977-B1

Abstract

A method of measuring an HVAC system airflow of an HVAC system having at least one airflow element selected from the group consisting of: an air register, a vent, a grill, a plenum, a duct, an economizer, a condenser, or a box temporarily attached to the HVAC system, wherein the box is in fluid communication and reversibly engaged with the HVAC system, wherein the HVAC system airflow is entering or leaving the least one airflow element. The method comprising drilling a single hole in the at least one airflow element and inserting an anemometer probe in the single hole and taking at least one airflow measurement at a location selected from the group consisting of: a near side airflow, a centerline airflow, a far side airflow, and an airflow between the near and far side; and calculating an average HVAC system airflow, based on the at least one airflow measurement.

Inventors

  • Robert J. Mowris

Assignees

  • Robert J. Mowris

Dates

Publication Date
20260512
Application Date
20250708

Claims (19)

  1. 1 . A method for measuring a Heating, Ventilating, Air Conditioning (HVAC) system airflow for an HVAC system, the HVAC system having at least one airflow element selected from the group consisting of: an air register, a vent, a grill, a plenum, a duct, an economizer outdoor air damper, a condenser coil inlet, a condenser fan outlet, or a box temporarily attached to the HVAC system, wherein the box is configured to be in fluid communication with the HVAC system and reversibly engaged with the HVAC system, wherein the HVAC system airflow is entering or leaving the box or the at least one airflow element of the HVAC system, the method comprising: drilling a single access hole in a near side of the at least one airflow element; inserting a hot-wire anemometer probe into the single access hole; positioning the hot-wire anemometer probe at a near side location disposed between the near side and a depth centerline of the at least one airflow element and taking a first airflow measurement while the hot-wire anemometer is in the single hole; positioning the hot-wire anemometer probe at a depth centerline location disposed between the near side and a far side of the at least one airflow element and taking a second airflow measurement while the hot-wire anemometer is in the single hole; positioning the hot-wire anemometer probe at a far side location disposed between the depth centerline and the far side of the at least one airflow element and taking a third airflow measurement while the hot-wire anemometer is in the single hole; and calculating an average HVAC system airflow based on the first airflow measurement, the second airflow measurement, and the third airflow measurement.
  2. 2 . The method of claim 1 , wherein the HVAC system airflow comprises one of: the HVAC system airflow across the at least one airflow element, an economizer outdoor airflow across the economizer outdoor air damper of the HVAC system or the box, wherein the box is configured to be in fluid communication with the economizer outdoor air damper and reversibly engaged with the economizer outdoor air damper, and a condenser airflow across the condenser fan outlet or the condenser coil inlet of the HVAC system or the box, wherein, the box is configured to be in fluid communication with the condenser fan outlet or the condenser coil inlet and reversibly engaged with the condenser fan outlet or the condenser coil inlet.
  3. 3 . The method of claim 1 , further comprising entering a cross sectional shape and dimensions of the at least one airflow element into a digital hot-wire anemometer tool, wherein the digital hot-wire anemometer tool is in electrical communication with the hot-wire anemometer probe.
  4. 4 . The method of claim 1 , further comprising adjusting the average HVAC system airflow across the at least one airflow element by at least one of: repairing an economizer, wherein the economizer comprises an economizer controller, an economizer actuator, the economizer outdoor damper or an economizer return air damper, sealing an economizer perimeter gap around the economizer outdoor air damper or the economizer return air damper, repairing crushed or leaking ducts, repairing insulation blocking airflow, opening registers, increasing duct size, increasing fan speed, defrosting and cleaning an evaporator coil, replacing a capacitor, cleaning a condenser coil, or cleaning a heat exchanger, wherein the economizer, the evaporator coil and the heat exchanger are disposed within the HVAC system and configured to change a temperature of the average HVAC system airflow.
  5. 5 . The method of claim 4 , further comprising reporting at least one of: a cooling efficiency improvement, wherein the cooling efficiency improvement is calculated based on measurements of an initial average HVAC system airflow and an initial temperature split across the evaporator coil before adjusting the average HVAC system airflow and a final average HVAC system airflow and a final temperature split across the evaporator coil after adjusting the average HVAC system airflow, wherein the temperature split across the evaporator coil is based on a return air drybulb temperature minus a supply air drybulb temperature; or a heating efficiency improvement, wherein the heating efficiency improvement is calculated based on the measurements of the initial average HVAC system airflow and an initial temperature rise across the heat exchanger before adjusting the average HVAC system airflow and the final average HVAC system airflow and a final temperature rise across the heat exchanger after adjusting the average HVAC system airflow, wherein temperature rise across the heat exchanger is based on the supply air drybulb temperature minus the return air drybulb temperature.
  6. 6 . The method of claim 1 , further comprising comparing the first airflow measurement to the second airflow measurement and the third airflow measurement and determining whether the near side location, the far side location, or the depth centerline location of the at least one airflow element provides a higher airflow and performing at least one of: measuring F far side airflow measurements and N near side airflow measurements, wherein the N is greater than the F, or measuring airflow for a longer duration at the near side location than at the far side location, wherein an N time is greater than an F time , when the near side location has the higher airflow than the far side location, measuring the F far side airflow measurements and the N near side airflow measurements, wherein the F is greater than the N or measuring the airflow for the longer duration at the far side location than at the near side location, wherein the F time is greater than the N time , when the far side location has the higher airflow than the near side location, measuring the F far side airflow measurements and the N near side airflow measurements, wherein the F is equal to the N or measuring the airflow for an equivalent duration at the far side location and the near side location, when the airflow at the near side location and the airflow at the far side location are less than the airflow at the depth centerline location, measuring C depth centerline airflow measurements, the N near side airflow measurements and the F far side airflow measurements, wherein the C is greater than the N and the C is greater than the F, or measuring the airflow for the longer duration at the depth centerline location than at the near side location or at the far side location, wherein a C time is greater than the N time and the C time is greater than the F time , when the depth centerline location has the higher airflow than the near side location and the depth centerline location has the higher airflow than the far side location, or calculating the average HVAC system airflow based on a weighted average of the N near side airflow measurements, the C centerline airflow measurements, and the F far side airflow measurements.
  7. 7 . The method of claim 1 , further comprising measuring N airflow measurements at the near side location, C airflow measurements at the depth centerline location, and F airflow measurements at the far side location, wherein the airflow measurements are measured on a higher airflow side over a longer time duration than the airflow measurements measured on a lower airflow side.
  8. 8 . The method of claim 1 , further comprising positioning a wind shield on a windward side of the box to reduce a wind-induced pressure on an open inlet side of the box, thereby improving airflow measurement accuracy during windy outdoor conditions.
  9. 9 . A method for measuring a Heating, Ventilating, Air Conditioning (HVAC) system airflow for an HVAC system, the HVAC system having at least one airflow element selected from the group consisting of: an air register, a vent, a grill, a plenum, a duct, an economizer outdoor air damper, a condenser coil inlet, a condenser fan outlet, or a box temporarily attached to the HVAC system, wherein the box is configured to be in fluid communication with the HVAC system and reversibly engaged with the HVAC system, wherein the HVAC system airflow is entering or leaving the box or the at least one airflow element of the HVAC system, the method comprising: drilling a single hole in the at least one airflow element; inserting a hot-wire anemometer probe in the single hole; taking a far side airflow measurement at a far side location of the at least one airflow element, a depth centerline airflow measurement at a depth centerline location between the far side and a near side of the at least one airflow element, and a near side airflow measurement at a near side location of the at least one airflow element while the hot-wire anemometer is in the single hole; determining which side of a depth centerline of the at least one airflow element provides a higher airflow; performing additional airflow measurements while the hot-wire anemometer probe is in the single hole, wherein more than 50% of the additional airflow measurements are measured on the higher airflow side and less than 50% of the additional airflow measurements are measured on a lower airflow side; and calculating an average HVAC system airflow based on a sum of the additional airflow measurements divided by a total quantity of the additional airflow measurements.
  10. 10 . The method of claim 9 , wherein the HVAC system airflow comprises one of: the HVAC system airflow across the at least one airflow element, an economizer outdoor airflow across the economizer outdoor air damper of the HVAC system or the box, wherein the box is configured to be in fluid communication and reversibly engaged with the economizer outdoor air damper, and a condenser airflow across the condenser fan outlet or the condenser coil inlet of the HVAC system or the box, wherein, the box is configured to be in fluid communication and reversibly engaged with the condenser fan outlet or the condenser coil.
  11. 11 . The method of claim 9 , further comprising entering a cross sectional shape and dimensions of the at least one airflow element into a digital hot-wire anemometer tool, wherein the digital hot-wire anemometer tool is in electrical communication with the hot-wire anemometer probe.
  12. 12 . The method of claim 9 , further comprising adjusting the average HVAC system airflow across the at least one airflow element by at least one of: repairing an economizer, wherein the economizer comprises an economizer controller, an economizer actuator, the economizer outdoor damper or an economizer return air damper, sealing an economizer perimeter gap around the economizer outdoor air damper or the economizer return air damper, repairing a crushed or a leaking duct, repairing an insulation blocking the airflow, opening at least one air register, increasing a duct size, increasing a fan speed, defrosting and cleaning an evaporator coil, replacing a capacitor, cleaning a condenser coil, or cleaning a heat exchanger, wherein the economizer and the evaporator coil are disposed within the HVAC system and configured to change a temperature of the average HVAC system airflow.
  13. 13 . The method of claim 12 , further comprising reporting at least one of: a cooling efficiency improvement, wherein the cooling efficiency improvement is calculated based on measurements of an initial average HVAC system airflow and an initial temperature split across the evaporator coil before adjusting the average HVAC system airflow, and a final average HVAC system airflow and a final temperature split across the evaporator coil after adjusting the average HVAC system airflow, wherein the temperature split across the evaporator coil is based on a return air drybulb temperature minus a supply air drybulb temperature, or a heating efficiency improvement, wherein the heating efficiency improvement is calculated based on the measurements of the initial average HVAC system airflow and an initial temperature rise across the heat exchanger before adjusting the average HVAC system airflow, and the final average HVAC system airflow and a final temperature rise across the heat exchanger after adjusting the average HVAC system airflow, wherein temperature rise across the heat exchanger is based on the supply air drybulb temperature minus the return air drybulb temperature.
  14. 14 . The method of claim 9 , wherein taking the far side airflow measurement at the far side location, the depth centerline airflow measurement at the depth centerline location, and the near side airflow measurement at the near side location comprises positioning the hot-wire anemometer probe between the depth centerline of the at least one airflow element and the far side of the at least one airflow element and taking the far side airflow measurement, positioning the hot-wire anemometer probe at the depth centerline of the at least one airflow element and taking the depth centerline airflow measurement, and positioning the hot-wire anemometer probe between the depth centerline of the at least one airflow element and the near side of the at least one airflow element, and taking the near side airflow measurement.
  15. 15 . The method of claim 9 , wherein performing the additional airflow measurements is based on durations, wherein airflow measurements on the higher airflow side are measured over a longer duration than the airflow measurements on the lower airflow side.
  16. 16 . A method for measuring a Heating, Ventilating, Air Conditioning (HVAC) system airflow, the HVAC system having at least one airflow element selected from the group consisting of: an air register, a vent, a grill, a plenum, a duct, an economizer outdoor air damper, a condenser coil inlet, or a condenser fan outlet, wherein a box is temporarily attached to the HVAC system and the box is configured to be in fluid communication with and reversibly engaged with the HVAC system and the HVAC system airflow is entering or leaving the box or the at least one airflow element of the HVAC system, the method comprising: inserting a hot-wire anemometer probe in a single hole, wherein the single hole is disposed within the box and is located on any side of the box, wherein the HVAC system airflow comprises one of: the HVAC system airflow across the box, wherein the box is in fluid communication with the at least one airflow element, and the box is configured to surround and be reversibly engaged with the at least one airflow element, such that the box overlaps with the at least one airflow element to capture HVAC system airflow through the at least one airflow element, an economizer outdoor airflow across the economizer outdoor air damper of the HVAC system or the box, wherein the box is configured to be in fluid communication with and reversibly engaged with the economizer outdoor air damper, and a condenser airflow across the condenser fan outlet or a condenser coil of the HVAC system or the box, wherein the box is configured to be in fluid communication with and reversibly engaged with the condenser fan outlet or the condenser coil inlet; and performing at least one action selected from the group consisting of: positioning the hot-wire anemometer probe at a near side location disposed between a near side and a depth centerline of the box and taking a near side airflow measurement with the hot-wire anemometer probe while the hot-wire anemometer probe is in the single hole, positioning the hot-wire anemometer probe at a centerline location disposed midway between the near side and a far side of the box and taking a centerline airflow measurement with the hot-wire anemometer probe while the hot-wire anemometer probe is in the single hole, positioning the hot-wire anemometer probe at a far side location disposed between the far side and the depth centerline of the box and taking a far side airflow measurement with the hot-wire anemometer probe while the hot-wire anemometer probe is in the single hole, and calculating an average HVAC system airflow based on the at least one airflow measurement.
  17. 17 . The method of claim 16 , further comprising entering a cross sectional shape and dimensions of the box into a digital hot-wire anemometer tool, wherein the digital hot-wire anemometer tool is in electrical communication with the hot-wire anemometer probe.
  18. 18 . The method of claim 16 , further comprising adjusting the average HVAC system airflow by at least one of: repairing an economizer, wherein the economizer comprises an economizer controller, an economizer actuator, the economizer outdoor damper or an economizer return air damper, sealing an economizer perimeter gap around the economizer outdoor air damper or the economizer return air damper, repairing crushed or leaking ducts, repairing insulation blocking the airflow, opening registers, increasing duct size, increasing fan speed, defrosting and cleaning an evaporator coil, replacing a capacitor, cleaning a condenser coil, or cleaning a heat exchanger, wherein the economizer, the evaporator coil and the heat exchanger are disposed within the HVAC system and configured to change a temperature of the average HVAC system airflow.
  19. 19 . The method of claim 16 , further comprising reporting an energy efficiency ratio (EER*) improvement, wherein the EER* improvement is calculated based on one of: measurements of an initial average HVAC system airflow and an initial temperature split across an evaporator coil and a final temperature split across the evaporator coil after adding refrigerant to an air conditioning system of the HVAC system, wherein temperature split across the evaporator coil is based on a return air drybulb temperature minus a supply air drybulb temperature, and the measurements of the initial average HVAC system airflow and the initial temperature split across the evaporator coil before adjusting the average HVAC system airflow and a final average HVAC system airflow and the final temperature split across the evaporator coil after adjusting the average HVAC system airflow.

Description

REFERENCE TO RELATED APPLICATIONS This application is a continuation-in-part and claims priority to U.S. Non-Provisional application Ser. No. 19/006,672, filed Dec. 31, 2024, which is hereby incorporated by reference, to the extent that it is not conflicting with the present application. TECHNICAL FIELD This patent specification relates to methods for measuring airflow in for a Heating, Ventilating, Air Conditioning (HVAC) system with or without an economizer connected to the HVAC system. BACKGROUND Buildings are cooled and/or heated by Heating, Ventilating, Air Conditioning (HVAC) systems to maintain comfortable conditions for occupants. Low airflow reduces thermal comfort and efficiency and increases operating time and energy use. HVAC system manufacturers require a design airflow across the evaporator or heat exchanger to provide the rated cooling or heating capacity. Known prior art economizers include an economizer frame that connects to a HVAC system cabinet, a supply and return damper assembly to provide an outdoor airflow ventilation to maintain indoor air quality and provide economizer cooling, and a relief damper assembly to vent excess air from the building to relieve the internal air pressure and balance the supply airflow. The economizer controller uses an actuator to position the economizer supply and return dampers using a coupling mechanism (i.e., gears, levers, rack and pinion, etc.), and sensors to measure air temperature, relative humidity and/or Carbon Dioxide (CO2) concentration in parts per million (ppm). The economizer controls the outdoor airflow, the return airflow and the temperature and humidity of the mixed airflow entering the HVAC system. Buildings are required to provide a minimum flow of outdoor air into their HVAC systems per the American Society of Heating Refrigeration and Air-Conditioning Engineers (ASHRAE) Standard 62.1 (ANSI/ASHRAE 62.1-2019. Standard Ventilation for Acceptable Indoor Air Quality) and the 2019 California Energy Commission (CEC) Building Energy Efficiency Standards for Residential and Nonresidential Buildings (https://ww2.energy.ca.gov/2018publications/CEC-400-2018-020/CEC-400-2018-020-CMF.pdf). When the outdoor airflow exceeds the minimum required airflow during severe weather (also referred to as the target minimum airflow), the additional airflow may introduce unnecessary hot outdoor air when the HVAC system is cooling the building or introduce unnecessary cold outdoor air when the HVAC system is heating the building. During severe weather, this unnecessary or unintended outdoor airflow reduces space cooling and heating capacity and efficiency and increases cooling and heating energy consumption and the energy costs required to provide space cooling and heating to building occupants. Known economizer controllers fully open the economizer supply damper and close the return damper to provide a maximum amount of outdoor air to cool the building without using Direct Expansion (DX) refrigerant-based Air Conditioning (AC) during cool weather when the Outdoor Air Temperature (OAT) is cooler than the Conditioned Space Temperature (CST) and the OAT is less than an economizer drybulb setpoint temperature referred to as a High-limit Shut-off Temperature (HST) or the outdoor air enthalpy is less than the enthalpy setpoint. During moderate weather when the OAT is less than the CST, but greater than the HST or the outdoor air enthalpy is greater than the enthalpy setpoint typically 28 British thermal units (Btu) per pound mass (Ibm) of dry air (da) (Btu/lbm), the economizer damper is set to a minimum outdoor air position and one or more DX AC compressors are used to provide mechanical cooling to the building. Known methods for measuring the amount of an economizer outdoor airflow introduced into buildings to meet minimum outdoor air ventilation requirements are inaccurate, and better methods are required to reduce cooling and heating energy use and improve indoor air quality, thermal comfort, and energy efficiency. Known techniques for cooling buildings with economizers are inefficient, and more effective methods are needed to reduce cooling energy consumption and enhance thermal comfort and energy efficiency. Known methods for measuring airflow in Cubic Feet per Minute (CFM) or liters per second (LPS) include a digital hotwire anemometer, a fan-powered flow hood (Duct Blaster), a pressure grid (Trueflow), or a balometer flow capture hood. Known methods for measuring a condenser airflow of an HVAC system use a static pressure, a temperature rise, or a balometer flow capture hood method. Known hotwire anemometers use heat transfer to determine an air velocity based on a relationship between a voltage output of an anemometer and an air flow velocity or an electrical current to maintain a temperature of a heated wire at a constant value. As the air flows over the wire and cools it down, the anemometer adjusts the electrical current flowing through the hotwire to maint