How can I measure temperatures around 170 C?

jmspaggi

Hi,

I'm will have soon a solar-hot-water-heating-system. And I want to do some "tests" with it. So I'm looking for a way to monitor the temperature at the exit of the 3 panels.

In sumer, the glycol inside the pipes can go up to 160 degrees. So I can't use a regular DS1620 of DS18B20, which measure only up to 127C.

Also, the pannels are on my roof, and the controller is 3 floors below. At about 30 feets from the panels.

I was thinking about using a 1-wire component because of the distance, but maybe also a 3-wire can works if I slow the shift-in shift-out.

So do you have any suggestion regarding the sensor I should us? The cheaper the better since this is not going to last forever.

Also, Mark (ElectricAye) pointed me that I can have so solder issues with a so high temperature. Can I "simply" use another soledring product?

Thanks for your recommandations,

JM

Leon

You will probably have to use a thermocouple.

Leon

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dandreae

The DS2760 Thermocouple is a one-wire device that will work for this project.· Here is a link for more information:

http://www.parallax.com/Store/Sensors/TemperatureHumidity/tabid/174/CategoryID/49/List/0/Level/a/ProductID/96/Default.aspx?SortField=ProductName%2cProductName

Features:

• 1-Wire interface allows multiple devices with just one BASIC Stamp I/O pin
• Cold Junction measurement: 0°C to +127°C (0.125°C resolution)
• Low power consumption: Active current = 90 µA max, Sleep current: 2 µA max

Key Specifications:

• Power Requirements: 2.5 V to 5.5 V @ 90 µA (max)
• Communication: Dallas 1-Wire® Interface with unique 64-bit device address
• Dimensions: 1.08 x 0.43 x 0.3 in (27.5 x 11 x 7 mm)
• Operating Temperature: -4 to 158 °F (-20°C to 70°C)

• Thermocouple Module
• K-Type (Chromel/Alumel) Element Temperature Range: 32 to 1873 °F (0 to 1023 °C)
• J-Type (Iron/Constantan) Element Temperature Range: 32 to 1873 °F (0 to 1023 °C)
• T-Type (Copper/Constantan) Element Temperature Range: 32 to 752 °F (0 to 400 °C)

Dave

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Dave Andreae

Parallax Tech Support·

jmspaggi

Hi Dave, hi Leon,

Thanks for your replies.

The space I have between 2 solar pannels is abour 1 inch, and the wires are 18" long. I can round the wire around the pipe, but will it still be correct like that? Also, since I will have to build 2 other boards for the 2 other wires, can I buy a DS2760 board from parallax without the wires?

Thanks,

JM

QuattroRS4

I have previously done the following -

Thermocouple to AD595 to LTC1298 to MCU.. The AD595 is a monolithic thermocouple amplifier - giving an output in the 0-5v range. The LT1298 is a dual channel 12bit ADC .

Regards,
John

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'Necessity is the mother of invention'

Those who can, do.Those who can’t, teach.