US 7,804,047 B2Granted

Temperature sensor diagnostic for determining water heater health status

AssigneeHoneywell International Inc.

InventorsRobert L. Zak, Douglas D. Bird, Brent Chian

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Abstract

A method and apparatus for determining a health status of a water heating device is disclosed. The water heating device may have a controller that incorporates logic to regulate the heater responsive to water temperatures detected at different areas within the water heating device by first and second sensors. Unfortunately, the first and second sensors may fail. To detect fault conditions or otherwise determine the heath status of the water heating device, a logic unit in the controller may perform a test on the first and/or second sensors so as to provide a test output. The logic unit may also determine whether the test output satisfies one or more predetermined thresholds. These predetermined thresholds may be indicative of a properly-functioning sensor. When the test output does not satisfy the at least one predetermined threshold, the logic unit may then set a fault condition indicative of improperly functioning sensors.

Claims7

Dependent claims

In a water heater having a first sensor, a second sensor, and a logic unit, wherein each of the first and second sensors are operable to provide an output indicative of water temperature, and wherein the logic unit uses the output indicative of water temperature to control heat cycling of the water heating device, a method for performing a sensor-matching test comprising:

the logic unit performing a test on at least one of the first and second sensors so as to produce a test output;
the logic unit determining whether the test output satisfies at least one predetermined threshold, wherein the at least one predetermined threshold is indicative of a properly-functioning sensor;
and
the logic unit setting a fault condition indicative of a non-properly-functioning sensor when the test output does not satisfy the at least one predetermined threshold,
wherein the step of performing the test on the at least one of the first and second sensors so as to produce a test output comprises:
(a) performing a heat cycle;
(b) using the first and second sensors to detect respective first and second water temperatures after the heat cycle completes;
(c) determining a first differential between the first and second water temperatures;
(d) using the first and second sensors to detect respective third and fourth water temperatures after the water heater has been idle for a predetermined period of time;
and
(e) determining a second differential between the third and fourth water temperatures;
and
wherein the step of determining whether the test output satisfies the at least one predetermined threshold comprises determining whether the first differential is greater than a first differential threshold and whether the first differential minus the second differential is greater than a second differential threshold, and wherein the step of setting the fault condition indicative of the non-properly-functioning sensor comprises setting the fault condition if the first differential is not greater than the first differential threshold.

10 more elements

the logic unit performing a sensor-contact test on at least one of the first and second sensors so as to produce a test output;
the logic unit determining whether the test output satisfies at least one predetermined threshold, wherein the at least one predetermined threshold is indicative of a properly-functioning sensor;
and
the logic unit setting a fault condition indicative of a non-properly-functioning sensor when the test output does not satisfy the at least one predetermined threshold,
wherein the steps of (i) performing the test on at least one of the first and second sensors so as to produce the test output, and (ii) determining whether the test output satisfies the at least one predetermined threshold comprise:
(a) initiating a heat cycle;
(b) using the first and second sensors to detect first and second water temperatures after a heat cycle initiates;
(c) determining a heating rate using the first and second water temperatures;
(d) determining whether the heating rate satisfies an expected-heating-rate threshold;
(e) repeating steps (b)-(d) if the heat cycle has not been occurring for a first predetermined period;
(f) completing the heat cycle;
(g) waiting a second predetermined period;
(h) using the first and second sensors to detect third and fourth water temperatures;
(i) determining a cooling rate using the third and fourth water temperatures;
and
(j) determining whether the cooling rate satisfies an expected-cooling-rate threshold, wherein the step of setting the fault condition indicative of the non-properly-functioning sensor comprises setting the fault condition when the heating rate does not satisfy the expected-heating-rate threshold.

13 more elements

Dependencies are inferred from the claim text.

Facts

Application: 10/997,258Filed 24 Nov 2004 · continuation in part
Priority: 5 Mar 2003
Published: US 2005/0077368 A114 Apr 2005
Granted: 28 Sep 2010
Term ends: Not estimatedThe source records don’t support an estimate.

Classification20 codes

F24H 9/2035
For water heaters: using fluid fuel
F24H 9/0005
Details: for water heaters
F24H 15/104
Characterised by the purpose of the control: inspection; Diagnosis; Trial operation
F24H 15/225
In the water storage tank: at different heights of the tank

Family

Application10/382,050Parent of this continuation-in-part · filed 5 Mar 2003
Application10/382,303Parent of this continuation-in-part · filed 5 Mar 2003
Application10/382,056Parent of this continuation-in-part · filed 5 Mar 2003
Application10/424,257Parent of this continuation-in-part · filed 25 Apr 2003
US 2005/0077368 A1Pre-grant publication · published 14 Apr 2005
US 6,959,876 B2Parent of this continuation-in-part
US 6,701,874 B1Parent of this continuation-in-part
US 7,317,265 B2Parent of this continuation-in-part
US 6,955,301 B2Parent of this continuation-in-part
US 2004/0173600 A1Published application
US 2004/0176859 A1Published application
US 2004/0211845 A1Published application
US 7,804,047 B2This patent

From the US filing history. Foreign family members aren’t listed.