초록 ▼

A method and apparatus are provided for maintaining a temperature between a first value and a second value. The method and apparatus utilize a heat transfer device capable of cycling through a series of cycles, the device being capable of changing the temperature from the second value to the first v

A method and apparatus are provided for maintaining a temperature between a first value and a second value. The method and apparatus utilize a heat transfer device capable of cycling through a series of cycles, the device being capable of changing the temperature from the second value to the first value when operational. During each cycle the device transfers heat for a first period of time when the temperature reaches the second volume until the first value is reached and thereafter the device stops transferring heat. The first period of time is compared to a desired cycle-on period of time during each cycle and the second temperature value then is adjusted for a subsequent cycle of the device so the first period of time when the device transfers heat approaches the desired cycle-on period of time. There may also be provided temperature controls for a liquid heater having a jacket containing the liquid. The jacket has an inner heated wall and an outer wall spaced apart from the inner wall. The controls include a temperature sensor capable of fitting to the jacket so that the sensor contacts the inner wall and the liquid. A control module monitors temperature sensed by the temperature sensor. The control module causes the heater to stop heating when the temperature is heated by the heater to a first value and causes the heater to heat when the liquid cools to a second value lower than the first value. The control module senses overheating when temperature sensed by the sensor increases to a third value, higher than the first value, when the heater is not heating, and then causes the heater to shut down.

대표청구항 ▼

What is claimed is: 1. A temperature control apparatus for a liquid heater having two fittings for connecting liquid conduits to the heater, one of the fittings being either an inlet or an outlet For liquid, another of the fittings being another of the inlet or the outlet for the liquid, the heater

What is claimed is: 1. A temperature control apparatus for a liquid heater having two fittings for connecting liquid conduits to the heater, one of the fittings being either an inlet or an outlet For liquid, another of the fittings being another of the inlet or the outlet for the liquid, the heater having a first temperature sensor adjacent to said one fitting and a second temperature sensor adjacent to said another fitting, the apparatus including a memory having values for a first temperature value, where the heater stops heating, a second temperature value lower than the first value, and a third temperature value higher than the first value, where the heater is shut off, both sensors being capable of sensing the first temperature value and the second temperature value and at least one of the sensors also sensing the third temperature value, and controls which compare temperature readings from each of the sensors wit each of the first temperature value, the second temperature value and the third temperature value, the heater having an overheat condition when a temperature exceeds the third temperature value, a high condition when a temperature exceeds the first temperature value, a normal condition when a temperature is between the second temperature value and the first temperature value and a low condition when a temperature is less than the second temperature value, the apparatus indicating the overheat condition when one of the sensors indicates a temperature exceeding the third temperature value, the high condition when either sensor indicates a temperature exceeding the first temperature value, but neither sensor indicates a temperature exceeding the third temperature value, a normal condition when either sensor indicates a temperature exceeding the second temperature value, but neither sensor indicates a temperature exceeding the third temperature value, and a low condition when both sensors indicate temperatures less than the second temperature value. 2. The apparatus as claimed in claim 1, wherein the second temperature value is variable between a minimum cycle-on temperature and a maximum cycle-on temperature, the heater having a warm condition when a temperature exceeds the maximum cycle-on temperature, the apparatus indicating the warm condition when one of the sensors indicates a temperature exceeding the maximum cycle-on temperature, but neither sensor indicates a temperature exceeding the first temperature value. 3. The apparatus as claimed in claim 1, wherein the heater has a faulted condition when a temperature reading exceeds a short threshold which indicates a short circuit, the short threshold exceeding the third temperature value, or when a temperature reading is less than an open threshold which indicates an open circuit, the open threshold being less than the minimum cycle-on temperature, the apparatus indicating the faulted condition when either sensor exceeds the short threshold or is less than the open threshold, the overheat condition being indicated when either of the sensors exceeds the third temperature value, but does not indicate the faulted condition. 4. A method of controlling temperatures in a liquid heater having two fittings for connecting liquid conduits to the heater, one of the fittings being either an inlet or an outlet for liquid, another of the fittings being another of the inlet or the outlet for the liquid, the heater having a first temperature sensor adjacent to said one fining and a second temperature sensor adjacent to said another filling, the method including retaining values for a first temperature where the heater stops heating, a second temperature where the heater commences heating, and a third temperature where the heater is shut off, both sensors being capable of sensing the first temperature value and the second temperature value and at least one of the sensors also sensing the third temperature value, comparing temperature readings from each of the sensors with each of the second temperature value, the first temperature value and the third temperature value, the heater having an overheat condition when a temperature exceeds the third temperature value, a high condition when a temperature exceeds the first temperature value, a normal condition when a temperature is between the second temperature value and the first temperature value and a low condition when a temperature is less than the second temperature value, the overheat condition being indicated when one of the sensors indicates a temperature exceeding the third temperature value, the high condition when either sensor indicates a temperature exceeding the first temperature value, but neither sensor indicates a temperature exceeding the overheat temperature, the normal condition when either sensor indicates a temperature exceeding the second temperature value, but neither sensor indicates a temperature exceeding the first temperature value, and a low condition when both sensors indicate temperatures less than the second temperature value. 5. The method as claimed in claim 4, wherein the second temperature value is varied between a minimum cycle-on temperature and a maximum cycle-on temperature, the heater having a warm condition when a temperature exceeds the maximum cycle-on temperature, the warm condition being indicated when one of the sensors indicates a temperature exceeding the maximum cycle-on temperature, but neither sensor indicates a temperature exceeding the first temperature value. 6. The method as claimed in claim 1, wherein the heater has a faulted condition when a temperature reading exceeds a short threshold which indicates a short circuit, the short threshold exceeding the third temperature value, or when a temperature reading is less than an open threshold which indicates an open circuit, the open threshold being less than the minimum cycle-on temperature, the faulted condition being indicated when either sensor exceeds the short threshold or is less than the open threshold, the overheat condition being indicated when either of the sensors exceeds the overheat temperature, but does not indicate the faulted condition. 7. A temperature control apparatus for a liquid heater having a first temperature sensor and a second temperature sensor, the apparatus including a memory having values for a first temperature where the heater stops heating, a second temperature value where the heater commences heating, and a third temperature value where the beater is shut oft and controls which compare temperature readings from each of the sensors with each of the first temperature value, the second temperature value and the third temperature value, both sensors being capable of sensing the first temperature value and the second temperature value and at least one of the sensors also sensing the third temperature value, the heater having an overheat condition when a temperature exceeds the third temperature value, a high condition when a temperature exceeds the first temperature value, a normal condition when a temperature is between the first temperature value and the second temperature value and a low condition when a temperature is less than the second temperature value, the apparatus indicating the overheat condition when one of the sensors indicates a temperature exceeding the third temperature value, the high condition when either sensor indicates a temperature exceeding the first temperature value, but neither sensor indicates a temperature exceeding the third temperature value, the normal condition when either sensor indicates a temperature exceeding the second temperature value, but neither sensor indicates a temperature exceeding the first temperature value, and a low condition when both sensors indicate temperatures less than the second temperature value. 8. The apparatus as claimed in claim 7, wherein the second temperature value is variable between a minimum cycle-on temperature and a maximum cycle-on temperature, the heater having a warm condition when a temperature exceeds the maximum cycle-on temperature, the apparatus indicating the warm condition when one of the sensors indicates a temperature exceeding the maximum cycle-on temperature, but neither sensor indicates a temperature exceeding the first temperature value. 9. The apparatus as claimed in claim 7, wherein the heater has a faulted condition when a temperature reading exceeds a short threshold which indicates a short circuit, the short threshold exceeding the third temperature value, or when a temperature reading is less than an open threshold which indicates an open circuit, the open threshold being less than the minimum cycle-on temperature, the apparatus indicating the faulted condition when both of the sensors indicate a faulted condition, whereby the heater is operational when only one sensor is present or if one of the sensors is faulted. 10. A method of controlling temperatures in a liquid heater, the heater having a first temperature sensor and a second temperature sensor, the method including retaining values for a first temperature value where the heater stops heating, a second temperature value where the heater commences heating, and a third temperature value where the heater is shut off, hot sensors being capable of sensing the first temperature value and the second temperature value and at least one of the sensors also sensing the third temperature value, comparing temperature readings from each of the sensors with each of the first temperature value, the second temperature value and the third temperature value, the heater having an overheat condition when a temperature exceeds the third temperature value, a high condition when a temperature exceeds the first temperature value, a normal condition when a temperature is between the first temperature value and the second temperature value and a low condition when a temperature is less than the second temperature value, the overheat condition being indicated when one of the sensors indicates a temperature exceeding the third temperature value, the high condition when either sensor indicates a temperature exceeding the first temperature value, but neither sensor indicates a temperature exceeding the third temperature value, the normal condition when either sensor indicates a temperature exceeding the second temperature value, but neither sensor indicates a temperature exceeding the first temperature value, and a low condition when both sensors indicate temperatures less than the second temperature value. 11. The method as claimed in claim 10, wherein the second temperature value is varied between a minimum cycle-on temperature and a maximum cycle-on temperature, the heater having a warm condition when a temperature exceeds the maximum cycle-on temperature, the warm condition being indicated when one of the sensors indicates a temperature exceeding the maximum cycle-on temperature, but neither sensor indicates a temperature exceeding the first temperature value. 12. The method as chimed in claim 10, wherein the heater has a faulted condition when a temperature reading exceeds a short threshold which indicates a short circuit, the short threshold exceeding the third temperature value, or when a temperature reading is less than an open threshold which indicates an open circuit, the open threshold being less than the minimum cycle-on temperature, the faulted condition being indicated when either sensor exceeds the short threshold or is less than the open threshold, the faulted condition being indicated when both of the sensors indicate a faulted condition, whereby the heater is operational when only one sensor is present or if one of the sensors is faulted. 13. A beater for liquids having two fittings for connecting liquid conduits to the heater, one of the fittings being either an inlet or an outlet for liquid, another of the fittings being another of the inlet or the outlet for the liquid, the heater having a first temperature sensor adjacent to said one fitting and a second temperature sensor adjacent to said another fitting, the heater including a memory having values for a first temperature value where the heater stops heating, a second temperature value where the heater commences heating, and an overheat temperature where the heater is shut off, both sensors being capable of sensing the first temperature value and the second temperature value and at least one of the sensors also sensing the third temperature value, and controls which compare temperature readings from each of the sensors with each of the first temperature value, the second temperature value and the third temperature value, the heater having an overheat condition when a temperature exceeds the third temperature value, a high condition when a temperature exceeds the first temperature value, a normal condition when a temperature is between the first temperature value and the second temperature value and a low condition when a temperature is less than the second temperature value, the a indicating the overheat condition when one of the sensors indicates a temperature exceeding the third temperature value, the high condition when either sensor indicates a temperature exceeding the first temperature value, but u either sensor indicates a temperature exceeding the third temperature value, the normal condition when either sensor indicates a temperature exceeding the second temperature value, but neither sensor indicates a temperature exceeding the first temperature value, and a low condition when both sensors indicates temperatures less than the second temperature value. 14. The heater as claimed in claim 13, wherein the second temperature value is variable between a minimum cycle-on temperature and a maximum cycle-on temperature, the heater having a warm condition when a temperature exceeds the maximum cycle-on temperature, the apparatus indicating the warm condition when one of the sensors indicates a temperature exceeding the maximum cycle-on temperature, but neither sensor indicates a temperature exceeding the first temperature value. 15. The heater as claimed in claim 13, wherein the heater has a faulted condition when a temperature reading exceeds a short threshold which indicates a short circuit, the short threshold exceeding the their temperature value, or when a temperature reading is less than an open threshold which indicates an open circuit, the open threshold being less than the minimum cycle-on temperature, the apparatus indicating the faulted condition when either sensor exceeds the short threshold or is less than the open threshold, the overheat condition being indicated when either of the sensors exceeds the third temperature value, but does not indicate the faulted condition. 16. A heater for liquids having a first temperature sensor and a second temperature sensor, a memory having values for a first temperature value where the heater stops heating, a second temperature value where the heater commences heating, and a third temperature value where the beater is shut off, both sensors being capable of sensing the first temperature value and the second temperature value and at least one of the sensors also sensing the third temperature value, and controls which compare temperature readings from each of the sensors with each of the first temperature value, the second temperature value and the third temperature value, the heater having an overheat condition when a temperature exceeds the third temperature value, a high condition when a temperature exceeds the first temperature value, a normal condition when a temperature is between the first temperature value and the second temperature value and a low condition when a temperature is less than the second temperature value, the controls indicating the overheat condition when one of the sensors indicates a temperature exceeding the third temperature value, the high condition when either sensor indicates a temperature exceeding the first temperature value, but neither sensor indicates a temperature exceeding the third temperature value, the normal condition when either sensor indicates a temperature exceeding the second temperature value, but neither sensor indicates a temperature exceeding the first temperature value, and a low condition when both sensors indicates temperatures less than the second temperature value. 17. The heater as claimed in claim 16, wherein the second temperature value is variable between a minimum cycle-on temperature and a maximum cycle-on temperature, the heater having a warm condition when a temperature exceeds the maximum cycle-on temperature, the controls indicating the warm condition when one of the sensors indicates a temperature exceeding the maximum cycle-on temperature, but neither sensor indicates a temperature exceeding the second temperature value. 18. The heater as claimed in claim 16, having a faulted condition when a temperature reading exceeds a short threshold which indicates a short circuit, the short threshold exceeding the the attempt or value, or when a temperature reading is less than an open threshold which indicates an open circuit, the open threshold being less than the minimum cycle-on temperature, the controls indicating the faulted condition when both of the sensors indicate a faulted condition, whereby the heater is operational when only one sensor is present or if one of the sensors is faulted.