Spa control system with improved flow monitoring

• US 20110072573A1
• Filed: 09/28/2009
• Published: 03/31/2011
• Est. Priority Date: 09/28/2009
• Status: Active Grant

• Current Assignee: Balboa Water Group Incorporated, Balboa Water Group LLC (Helios Technologies, Inc.)
• Original Assignee: Balboa Water Group Incorporated
• Inventors: Hollaway, Jerrell P.
• Granted Patent: US 8,392,027 B2
• Time in Patent Office: Days
• US Class Current: 4/493
• CPC Class Codes: A61H 2201/5082 Temperature sensors
• CPC Class Codes: A61H 33/005 Electrical circuits therefor

Abstract

A spa control system that measures the flow of water through the heater and accurately reports water temperature in the spa using only one solid-state sensor in the heater. The working condition of the sensor is first determined by activating the heater for a brief period of time, with the circulation pump de-energized, and watching for the expected heat rise at the sensor. A small rise is sufficient to proceed with the flow test. The rate of flow is now determined by energizing the pump, with the heater still de-energized, and observing the rate in which the moving water cools the inside of the heater. If there is no circulation of water through the heater, the temperature of the sensor will continue to rise from the energy applied when the heater was briefly energized. This rise will be quite significant and a clear indication of a flow problem. If the flow is found to be adequate, the heater will be energized for a normal period of time. The sensor is now carefully monitored for a sudden increase in temperature, which would indicate loss of a normal flow of water. It is known that the temperature of the water in the spa will be within one or two degrees of the observed temperature in the heater, even when the heater is energized. The water temperature can, therefore, be accurately reported to the user just from measuring the temperature of the water in the heater. The only problem with making all measurements at the heater is that the real water temperature is unknown when the pump is not running. This problem can result in short heating cycles, or create the need to run the pump several times per day just to check on the real water temperature. The present invention uses artificial intelligence to find the difference between the heater temperature and the real water temperature and then applies the learned difference to the heater temperature measurement as an offset for the next heater and pump activation, where a new offset will be calculated.

Claims

1. A spa control system comprising:

A vessel for holding water;

A heater for heating said water;

A pump for circulating said water through said heater;

A single solid-state temperature sensor positioned near the heating element of said heater and exclusive to any other temperature sensor in said system;

A microprocessor coupled to said heater, said pump, and said sensor for the purpose of controlling said heater and said pump based on the temperature measurements of said sensor.

2. The system in claim 1, wherein said microprocessor records a first temperature measurement at said sensor while said pump and said heater are de-energized but after said heater has been recently energized, and records a second temperature measurement after said pump has been energized for a period of time, with said microprocessor controlling said heater according to the difference between first measurement and said second measurement.

3. The system in claim 2, wherein the rate of change between said first measurement and said second measurement is calculated by said microprocessor and

used to determine the amount of water flow through said heater.

4. The system in claim 1, wherein a second solid-state sensor is placed adjacent to said single solid-state sensor to provide redundancy for the sensor function.

5. The system in claim 4, wherein said sensors share a common housing means.

6. The system in claim 4, wherein said measurements of said sensors are averaged together by said microprocessor.

7. The system of claim 4, wherein said measurements of said sensors are compared by said microprocessor so that whenever said measurements are different by a prescribed amount of difference said microprocessor de-energizes said heater.

8. The system of claim 2, wherein said pump circulates said water through said heater prior to said first temperature measurement.

9. The system of claim 8, wherein said pump circulates said water for a prescribed period of time prior to said first temperature measurement.

10. The system of claim 8, wherein said pump circulates said water until the rate of change of said water temperature at said sensor is within a prescribed rate.

11. The system in claim 1, wherein said microprocessor reacts to a first temperature measurement of said sensor when it is less than a preferred temperature for said water and energizes said pump and said heater to raise the temperature of said water to said preferred temperature.

12. The system in claim 11, wherein said pump is energized for a period of time before said heater is energized so that a second temperature measurement can be made which is more indicative of said water temperature.

13. The system in claim 12, wherein any difference between said first measurement and said second measurement is added to said first measurement in the next comparison of said first measurement and said preferred temperature.

14. The system in claim 12, wherein a third temperature measurement is made, after said pump and said heater are both energized, and compared to said second temperature measurement so that a rate of change greater than a prescribed rate of change will cause said microprocessor to de-energize said heater.

15. The system in claim 14, wherein a fourth temperature measurement is made, while heater is de-energized and pump is still energized, and compared to said third temperature measurement so that said heater will be energized again if the difference between said measurements is less than a prescribed difference.

20. The system in claim 13, wherein said difference may be adjusted according to an observed rate of change in said heater temperature measurements while said pump is de-energized.

16. A method of controlling a heater in a spa with a spa control system having only one temperature sensor in said system, comprising:

De-energizing a pump that normally circulates water through said heater;

Energizing said heater;

De-energizing said heater after said heater has been energized for a short period of time;

Monitoring the temperature at said heater with said sensor until an increase in temperature is seen and recorded;

Energizing said pump and monitoring said temperature at said heater until said increase is reduced by moving water from said pump and recording the time required to accomplish said reduction in said increase;

Calculating the rate of change of said reduction and energizing said heater for a longer period of time only if said rate is greater than a prescribed rate.

17. The method in claim 16, wherein said pump circulates said water through said heater until the rate of change in temperature measurements at said sensor is less that a prescribed rate prior to applying said method.

18. The method of claim 16, wherein additional temperature measurements are made while said heater is energized for said longer period of time for the purpose of de-energizing said heater if the rate of change of said measurements is greater than a prescribed rate.

19. The method of claim 18, wherein, with said pump still energized, heater temperature measurements are made after said heater is de-energized so that said heater can be re-energized if said heater temperature measurements and said additional temperature measurements are within a prescribed difference.