[clug] [OT] Monitoring hot water system temperatures

Eyal Lebedinsky eyal at eyal.emu.id.au
Wed Aug 4 05:02:51 UTC 2021

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.

I do a similar think but use dedicated sensors (One-Wire DS18B20) to send packets to a simple server which
appends to a log file. I attached the sensors to the pipes which is good enough for me. I do not even know
if the sensors my HWS uses are thermocouples of digital sensors.

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.

Software can be written using Arduino IDE and there are many examples of this around. Just search for
	arduino read thermocouple

This should be a fun project, or maybe someone will suggest a ready made solution as you asked.


> I have a hot water storage system with solar heating.  It has a controller that takes temperature from three probes, and these come back in to the controller where it decides when to turn on the pumps.  The controller doesn't log the temperatures, but I want to, to understand the efficiency of the system.
> The probes come as bare wires into the controller, and one idea is to then feed those wires also into some IoT home monitoring system that can then make the current temperature available over an API or similar.  I know I'd have to do some calibration such that a voltage of X translates to a temperature of Y.
> Question: is there a short cut for this?  A prebuilt device I can buy that will do this with a minimum of fuss?  Or are there any other suggestions?
> Thanks,
> Tony

Eyal Lebedinsky (eyal at eyal.emu.id.au)

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