[clug] [OT] Monitoring hot water system temperatures

[Tony Lewis]

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.

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