[clug] [OT] Monitoring hot water system temperatures

Tony Lewis tony at lewistribe.com
Wed Aug 4 14:38:48 UTC 2021

Thanks Eyal.

On 4/8/21 3:02 pm, Eyal Lebedinsky via linux wrote:
> Hi Tony
> On 04/08/2021 12.13, Tony Lewis via linux wrote:
>> Hoping there is enough knowledge on this list to point me in the 
>> right direction.
>> I'm looking for an IoT device that can measure the temperature of 
>> three thermocouples *in parallel* with its current system usage for 
>> our hot water system, and log or transmit them somehow.
> This can be done simply using something like an ESP32. It can read a 
> few voltages and report over WiFi
> to anywhere.
Looking at the specs, this looks like a good fit, thanks.
> Do you know the characteristics of your sensors? What is the voltage 
> range they provide? The ESP is a 3.3v device.
> Thermocouples provide very low voltage and there are standard devices 
> to interface it to the processor.

I believe they are thermistors, only because the specs show a table of 
resistances vs temperatures.  It's to be confirmed, but I'm hoping that 
this will translate to a voltage across the thermistor, created so the 
controller itself can read the temperature.  If so, I might just be able 
to measure it.

I'm thinking it's likely I might need opamps to amplify and/or buffer 
the signal so that in theory I don't impact the operation of the 
controller itself.

> Software can be written using Arduino IDE and there are many examples 
> of this around. Just search for
>     arduino read thermocouple
Thanks, but I can't use my own thermocouples because I am trying to 
measure the temperature inside the tank, so unless I start tinkering 
with the HWS itself, I think I'm best off trying to leverage off the 
existing thermistors / thermocouples.


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