HVAC AIR FILTER MONITOR WITH SENSOR COMPENSATION
First Claim
1. A method of monitoring a status of an air filter of an HVAC system, wherein the HVAC system has a fan for driving air through the air filter of the HVAC system, the method comprising:
- a) turning the fan “
off”
so that substantially no air is driven through the air filter;
b) with the fan “
off”
, measuring a sensor offset differential pressure value between an upstream side of the air filter and a downstream side of the air filter;
c) storing the sensor offset differential value;
d) turning the fan “
on”
so that air is driven through the air filter;
e) with the fan “
on”
, measuring an un-compensated differential pressure value between the upstream side of the air filter and the downstream side of the air filter;
f) determining a compensated differential pressure value by removing the sensor offset differential value from the un-compensated differential pressure value;
g) determining the status of the air filter based, at least in part, on the compensated differential pressure value; and
h) displaying the status of the air filter on a display of an HVAC controller.
3 Assignments
0 Petitions
Accused Products
Abstract
Sensor offsets for an air filter monitor installed in an HVAC system may be determined by measuring a sensor offset differential pressure value across an air filter when substantially no air flow exists through the air filter. The sensor offset differential pressure value obtained at or near zero flow may represent the sensor offset for the air filter monitor. The sensor offset differential pressure value may be used to compensate an un-compensated differential pressure value obtained during flow conditions.
71 Citations
19 Claims
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1. A method of monitoring a status of an air filter of an HVAC system, wherein the HVAC system has a fan for driving air through the air filter of the HVAC system, the method comprising:
-
a) turning the fan “
off”
so that substantially no air is driven through the air filter;b) with the fan “
off”
, measuring a sensor offset differential pressure value between an upstream side of the air filter and a downstream side of the air filter;c) storing the sensor offset differential value; d) turning the fan “
on”
so that air is driven through the air filter;e) with the fan “
on”
, measuring an un-compensated differential pressure value between the upstream side of the air filter and the downstream side of the air filter;f) determining a compensated differential pressure value by removing the sensor offset differential value from the un-compensated differential pressure value; g) determining the status of the air filter based, at least in part, on the compensated differential pressure value; and h) displaying the status of the air filter on a display of an HVAC controller. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method of monitoring a status of an air filter of an HVAC system, wherein the HVAC system has a fan for driving air through the air filter of the HVAC system, the method comprising:
-
operating the HVAC system in a heating mode, cooling mode or ventilation mode; occasionally entering an air filter monitoring mode, wherein the air filter monitoring mode includes; turning the fan of the HVAC system “
off”
so that substantially no air is driven through the air filter;with the fan “
off”
, measuring a sensor offset differential pressure value between an upstream side of the air filter and a downstream side of the air filter;storing the sensor offset differential value; occasionally entering an air filter monitoring mode, wherein the air filter monitoring mode includes; turning the fan “
on”
so that air is driven through the air filter;with the fan “
on”
, measuring an un-compensated differential pressure value between the upstream side of the air filter and the downstream side of the air filter;determining a compensated differential pressure value by removing the stored sensor offset differential value from the un-compensated differential pressure value; determining the status of the air filter based, at least in part, on the compensated differential pressure value; displaying the status of the air filter on a display of an HVAC controller. - View Dependent Claims (15, 16)
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17. An HVAC controller for monitoring a status of an air filter of an HVAC system, wherein the HVAC system has a fan for driving air through the air filter of the HVAC system, the HVAC controller comprising:
-
a controller; a memory coupled to the controller; a display coupled to the controller; wherein the controller is programmed to; send a command to turn the fan of the HVAC system “
off”
so that substantially no air is driven through the air filter;with the fan “
off”
, obtain a sensor offset differential pressure value that is representative of a sensed pressure between an upstream side of the air filter and a downstream side of the air filter;store the sensor offset differential value in the memory; send a command to turn the fan of the HVAC system “
on”
so that air is driven through the air filter;with the fan “
on”
, obtain an un-compensated differential pressure value that is representative of a sensed pressure between the upstream side of the air filter and the downstream side of the air filter;determine a compensated differential pressure value by removing the sensor offset differential value from the un-compensated differential pressure value; determining the status of the air filter based, at least in part, on the compensated differential pressure value; and displaying the status of the air filter on a display. - View Dependent Claims (18, 19)
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Specification