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Multiple Thermistor Temperature Logging

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Multiple Thermistor Temperature Logging

Postby Mark Dorogi » Mon Dec 22, 2003 5:00 am

I am putting in a solar water heating system and would like to measure temperatures in a number of places. Typically these systems use 10kohm thermistors. The curve of resistance vs temperature for these standard sensors is commonly available.

Would it be possible to record temperatures from say 16 of these thermistors, every few seconds? What hardware would be necessary?
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Postby ricardo » Wed Dec 24, 2003 10:07 am

Hi,

You should be able to do this with an ADC-11 or ADC-16. There will be some simple signal conditioning involved so you can calculate the resistance by measuring the voltage. You will get a data sheet with the unit explaining how to do the signal conditioning to measure Temperature from Precision Thermistors.

Best Regards,

Ric
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Postby Guest » Mon Feb 09, 2004 2:44 am

Now my solar hot water system is up and running and I am thinking again about logging some temperature data.

You mention simple signal conditioning. Can you explain a little? I assume some additional hardware is needed to turn the thermistor resistance value into a voltage (0 to 2.5V) that is then input into the ADC. Is this correct?
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Postby markspencer » Mon Feb 09, 2004 10:35 am

Hi,

The siganal conditioning will only need to be done if the thermister gives very small changes or if the voltage can go above the 2.5 volts for the unit. You would need to design you circuitry, so that the voltage is measured across the resistor. and therefore you can calculate the resistance change.

A look up table would be required to convert the voltage into a scaled value in temperature. The details of this would be provided by the thermisters data sheet.

Best regards,
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Re: Multiple Thermistor Temperature Logging + BACnet

Postby jmaril » Tue Feb 24, 2004 9:58 pm

Mark Dorogi wrote:I am putting in a solar water heating system and would like to measure temperatures in a number of places. Typically these systems use 10kohm thermistors. The curve of resistance vs temperature for these standard sensors is commonly available.

Would it be possible to record temperatures from say 16 of these thermistors, every few seconds? What hardware would be necessary?


I have the same project.
Could you please tell me where you are in this business ?
What did you buy and made. I need to do the same.
--------------
Besides a solar heating system, it's also very useful to instrument and control any heating system of significant size:
- measuring temperature, and sometimes flow in primary and secondary hydraulic circuits;
- recording in real time gaz and water volume with reed contacts on counters;
- recording some quality parameters like pH, iron concentration...
ASHRAE, The American Society of Heating Refrigeration and Air-conditionning Engineers has defined the BACnet standard of such data communication.
I thinck I would like suggest PICO TECHNOLOGY enter this business and help his clients on this quite new and growing applications
Who can discuss with that with me ?
jmaril
 


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