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Track When Thermostats Are Calling For Heat

I`m new to OpenEnergyMonitor but have my emonpi up and running with 6 temperature sensors measuring the flow and return temps on our heating system and UFH.

I`d like to include in the graph when my thermostats are calling for heat so I can see the heat up time etc.

Is that type of thing possible?

how many thermostats if one you could use pulse count and a another relay on the thermostat to be trigger.

if more then one you could use say an another PI, ESP, or Arduino and using push button code (and a small secondary relay on you thermostat wire as the button) to determine which thermostat is on or off and then send the data to emon to be logged

Thanks for the reply, it would be 3 possibily 4.

I did wonder if I could use another temp sensor board if it channel could tell me when a circuit was open or closed. It’s voltage free switching so I know it’s not going to fry my Pi.

You should - at least in theory - be able to use the temperature sensor input of the emonPi, but there would be a lot of development work and you’d need to make serious changes to the code inside the “emon” front end part. And then find the best way to present the data in emonCMS.

The temperature sensors are One-wire devices, and there is the Maxim DS2413 with two I/O pins (so it would do 2 thermostats). Quickly looking at the data sheet, it appears each will accept a switch or a voltage input, and be able to be polled and report on the same bus as the temperature sensors.

Adafruit do one on a breakout board: https://cdn-learn.adafruit.com/downloads/pdf/adafruit-1-wire-gpio-breakout-ds2413.pdf.

personally I think it be easier just to use an esp or arduino to tell whether the thermostat is on or off and then publish the info to emon - then if anything goes wrong the most you will do is end up killing is $5-$10 esp or arduino – you should be able to do alot of them. just use a button code for analog and MCP3208 you should be able to do 8 or a multiplexer CD74HC4067 and do 16 of them and a relay on each low volt thermostat wire ( or on the high volt wire on heating system ) to act as the “button”

I think you are correct - I was pointing out that it should be possible to do it with the emonPi (or indeed with an emonTx), but that it would be a complicated process to integrate with the existing software.