Air filter monitor for HVAC units
AssigneeCarrier Corporation
InventorsRoger S. Bankus, Thomas L. DeWolf, Robert P. Dolan, Brian D. Inman
Life of this patent
Estimating the term…
Abstract
An electronic system for monitoring the condition of the filter in an HVAC unit includes a controller which issues at least one command to a circuit for the motor of the fan producing airflow through the filter. The command to the driver circuit is associated with a desired run speed for the fan. The controller is operative to compute the speed of the fan following issuance of the command to the motor drive circuit. This computed speed is compared to a predetermined fan speed that would normally occur when the filter is dirty. The electronic system is operative to generate a warning in the event that the computed fan speed does not compare favorably with the predetermined fan speed.
Claims13
A unit for conditioning air having an air filter located in an air flow path and a fan for causing air to flow through the filter;
- wherein said unit includes a system for detecting whether the air filter needs to be replaced based upon a reading of the speed of the fan, said system comprising:
- a sensor for detecting movement of the fan;
- a device for entering an indication of desired speed for the fan;
- a motor control connected to the motor for the fan;
- and
- a processor operative to note the entered indication of desired speed for the fan and to thereafter select a command for the motor control based upon the entered indication of desired speed so as to cause the motor to rotate the fan at the desired speed when the air filter located in the air flow path is clean, said processor being responsive to the output of said sensor for computing the speed of the fan, said processor being furthemore operative to compare the computed speed with a predetermined speed of the fan associated with the entered indication of desired speed for the fan, the predetermined speed being indicative of a dirty filter located in the air flow path when the motor control is commanded to rotate the fan at the desired speed, said processor being furthermore operative to generate a signal indicating when a dirty filter has been detected as a result of comparing the computed speed with the predetermined speed.
A process for detecting whether a filter needs to be replaced within an air conditioning unit wherein air is caused to flow through a filter by a rotating fan said process comprising the steps of:
- noting that an indication as to a preferred fan speed has been selected;
- generating a command to a control for a motor which rotates the fan in response to the noted indication as to a preferred fan speed having been selected;
- and
- selecting a predetermined fan speed of the fan indicating when the filter needs to be replaced based upon the noted indication as to a preferred fan speed;
- detecting the speed of the rotating fan;
- comparing the detected speed of the fan with the selected predetermined speed of the fan indicating when the filer needs to be replaced;
- and
- generating an indication that the filter needs to be replaced when the detected speed does not favorably compare with the selected predetermined speed of the fan indicating the filter needs to be replaced.
Dependencies are inferred from the claim text.