Abstract: A system and method for introducing external air into an enclosure having an exhaust fan for removing internal air at an outflow rate. A sensor measures a quantifiable characteristic which is indicative of the outflow rate. Based on the measured quantifiable characteristic, a controller determines a speed of a makeup air fan that results in the inflow rate matching the outflow rate, and opens a damper and runs the makeup air fan at the determined speed. For example, the sensor may measure an amount of electrical current flowing to the exhaust fan, and low and high speed exhaust fan values are stored in a memory, and corresponding low and high makeup air fan speeds are set. The controller then controls operation of the makeup air fan based on the amount of current flowing to the exhaust fan and the corresponding makeup air fan speed to match the inflow and outflow rates.

Abstract: A system and method for selecting a proper fan for an air flow system for mitigating radon in a building. An air flow system includes a pipe connected to an access hole extending through the center of a slab and into the underlying soil. A test hole also extends through the slab. A variable speed test fan is installed in the pipe, and a manometer is installed to measure a static pressure value of the overall system. A chart or a computer program is configured to correlate a particular speed of the test fan and a particular static pressure value when the test fan creates an initial draw at the test hole with an identification of a proper fan. The proper fan has an operating speed which is closest to the particular speed. The proper fan is then installed in place of the test fan in the air flow system.

Abstract: A ventilation system is operable to ventilate gases from an enclosed building. The ventilation system broadly includes a ventilation tube, a ventilation fan, and a flexible flow-through coupler. The tube is operable to extend into and out of the building for transmitting gases along the length of the tube. The fan is in fluid communication with the ventilation tube and is located to pump gases along the tube length. The coupler connects and fluidly communicates the fan to the ventilation tube, with the flexible coupler isolating at least part of the ventilation tube from vibration caused by the fan. The coupler comprises a flexible material with a Shore A hardness less than about 50.

Abstract: A system and method for controlling activation and deactivation of an exhaust system for ventilating an enclosed space, such as a bathroom. The system includes a humidity sensor, a memory element, and a processing element. The sensor measures a humidity value in the space, and the memory element stores that value along with a series of previously measured humidity values. The memory also stores a look-up table which specifies activation and deactivation criteria for the exhaust system based on the measured humidity value and a normal humidity value. The processing element calculates the normal humidity value based on a weighted average of the stored series of humidity values, consults the look-up table, and controls the exhaust system as specified by the look-up table. The measured humidity value is added to the stored series of values at a first interval, and the normal humidity value is re-calculated at a second interval.

Abstract: A system and method for introducing external air into an enclosure having an exhaust fan for removing internal air at an outflow rate. A sensor measures a quantifiable characteristic which is indicative of the outflow rate. Based on the measured quantifiable characteristic, a controller determines a speed of a makeup air fan that results in the inflow rate matching the outflow rate, and opens a damper and runs the makeup air fan at the determined speed. For example, the sensor may measure an amount of electrical current flowing to the exhaust fan, and low and high speed exhaust fan values are stored in a memory, and corresponding low and high makeup air fan speeds are set. The controller then controls operation of the makeup air fan based on the amount of current flowing to the exhaust fan and the corresponding makeup air fan speed to match the inflow and outflow rates.