Abstract: The disclosure provides a method of operating a (HVAC) system. The method includes measuring a concentration of a gas in the target space, and determining that the concentration exceeds a gas concentration threshold. The method includes determining that operation of the HVAC system in a ventilation mode is indicated to reduce the concentration of the gas. The method includes determining a total capacity of the HVAC system, and determining a current capacity of the HVAC system. The method includes causing the HVAC system to operate in the ventilation mode after validating that the total capacity is greater than the current capacity during operation of the HVAC system in the ventilation mode.

Abstract: A method includes setting a desired cleaning time and desired air changes. A volume of a controlled space is determined. A total clean air volume to be delivered to the controlled space is determined based on the volume and the desired air changes. (a) A remaining clean air volume to be delivered to the controlled space is determined. (b) A remaining cleaning time is determined. (c) In response to determining that a ventilation unit is not present: a recirculated air flow rate is determined based on the remaining clean air volume and the remaining cleaning time, a blower flow rate is set to the determined recirculated air flow rate, the method waits for an idle time, and a delivered clean air volume already delivered to the controlled space is determined. Operations (a), (b), and (c) are repeated until the total clean air volume is delivered to the controlled space.

Abstract: An indoor air quality monitor for an HVAC system includes a monitor body formed with a plurality of chambers defined at least in part by chamber walls. A bypass chamber allows for a majority of airflow entering the monitor to pass through. An intake chamber coupled to the bypass chamber allows for a portion of air to be removed for sampling by a particulate sensor. Air from the particulate sensor is discharged to an outlet chamber that is fluidly coupled to a downstream portion of the bypass chamber. The fluid requirements of the particulate sensor are maintained without overwhelming or underwhelming the particulate sensor.

Abstract: A controller is configured to operate a heating, ventilation, and air conditioning (HVAC) system based on a plurality of concentration measurements received from a gas sensor, wherein the gas sensor is disposed within a sensor housing upstream of an evaporator coil. The controller is configured to receive the plurality of concentration measurements and determine if a concentration of total volatile organic compounds (TVOCs) in an airflow exceeds a first threshold value. The controller is further configured to operate the HVAC system in a second mode of operation to increase ventilation in response to determining that the concentration of TVOCs in the airflow does exceed the first threshold value, wherein a volume of air is introduced into and discharged from the HVAC system during the second mode of operation.

Abstract: A controller is configured to operate a heating, ventilation, and air conditioning (HVAC) system based on a first plurality of particulate matter measurements and a second plurality of particulate matter measurements. The controller is configured to determine an air filter efficiency for an air filter based on the received first plurality of particulate matter measurements and the received second plurality of particulate matter measurements. The controller is further configured to determine if a quantity of particulate matter in an airflow exceeds a first threshold value based on the received second plurality of particulate matter measurements. In response to determining that the quantity of particulate matter in the airflow does exceed the first threshold value, the controller is configured to transmit a notification indicating an action to inspect the air filter.

Abstract: A heating, ventilating, and air conditioning (HVAC) system includes at least one indoor air quality monitor. The indoor air quality monitor is formed with an arrangement of chambers—intake chamber, low-flow chamber, and outlet chamber—such that a particulate sensor on an interior and another air quality sensor are neither overwhelmed nor underwhelmed by air flow to the sensors. The indoor air quality monitor may be arranged for attaching to a surface in a conditioned space for sampling air therein or may include a bypass chamber that fluidly couples to an HVAC duct. Other systems and methods are presented.

Abstract: An indoor air quality monitor for an HVAC system includes a monitor body formed with a plurality of chambers defined at least in part by chamber walls. A bypass chamber allows for a majority of airflow entering the monitor to pass through. An intake chamber coupled to the bypass chamber allows for a portion of air to be removed for sampling by a particulate sensor. Air from the particulate sensor is discharged to an outlet chamber that is fluidly coupled to a downstream portion of the bypass chamber. The fluid requirements of the particulate sensor are maintained without overwhelming or underwhelming the particulate sensor. Other systems and monitors are presented; some include separate TVOC sensors.