Temp sensor for heating tube


Any suggestions on what kind of temp sensor to use on PI.
I need to put the sensor on a tube (outside) of the radiator.


@integral have a look at this DHT11/DHT22 with Raspberry Pi


As @shramik_salgaonkar mentioned the DHT11 and DHT22 sensors are great (also give you added humidity should you need it) and there’s also the DS18B20 temp sensor. The best part about the DS18B20 is that they are waterproof (if you get the kind I linked above) and automatically detected by the Cayenne Pi agent.


Hi to all of you.
I have installed the DS18B20 and working fine.
I have a typical project with the temp sensor and a relay output.
I say that when the temp goes over 85 then relay on
When the temp goes below 45 the relay off.
Many times (3 or 5 of 10) the relay stays on even when the temp goes below 45 and i have to turn the relay of manualy
Any suggestions for ths problem?
Thank u


Ultimately, you want to make the decision to turn off the relay in the local code, as you can’t always rely on your internet connection being active.

This sounds odd though. The only thing I can think of is there is enough voltage on the pin in the off state for your relay board to stay on. What relay board are you using?

Can you actuate the relay multiple times with a digital button and see if you get the same intermittentcy?




I have try to actuate the relay through the mobile app and it works fine all the times.
Something is wrong when the relay have to turn off through the trigger.
The relay is a typical 4 channel relay module and im using only one relay.

The internet connection is a mandatory to run a trigger?


The internet connection is a mandatory to run a trigger?

Yes, with triggers, the decision is made in the cloud based on the data received. When the condition is met, then the relay is turned on or off.




I will verify that the internet connection is ok.
Maybe this is the problem

Thank you for your help


Someone else is using this functionality for their fishtank with a Pi. Might be software.




So you suggest reinstall the software?

And also im curious. If the inetrnet is lost what happens to fishtank? :slight_smile:


Yup, that’s why I always want my decisions made locally.

Dashboards are great for making manual decisions, setting setpoints, logging data, or triggering alarms, but if I need to turn on and off a heater, I want those decisions to be made locally and not dependent on cloud functionality.



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