Looking for smart thermometer with external sensor

Anyone know of a smart device that measures temp with an external sensor/probe?
I’m looking to attaching it to some heating pipes and measure inflow/outflow water temps.

Worst case, perhaps a RPi solution?

RPI would be overkill. ESP8266 or ESP32 and ESPHome firmware. Has excellent integration into Home Assistant.

1 Like

I’m doing this same thing using esp8266 and 2 DS18B20, to give me input and output temp on my heat run to my bedroom from the boiler.

What is your overall intentions? Is this just for data gathering? Do you plan on using these sensors for control, how fast do you need them to react?

I use esphome with 2 types of sensors dallas and thermocouplings. The TC’s are ultra responsive almost a minute difference in some cases compared to the dallas. Dallas sensors are 5 for $10, one thermocoupling will run $20+ each.

Thanks for quick answers.

Yes, it’s initially for data gathering. Perhaps automation later on, but as mentioned above. We’re talking water pipes, so it’s a slow system.

Initially I was hoping for some sort of ZigBee device with external temp sensor. But that seems unavailable.

ESP sounds great, but I have no experience in this whatsoever. So I don’t even know what hardware is required… :confused:

mysensors is similar but I believe they can use zigbee. This is a test direct on the radiator. the lag on the dallas prevented them from reading the max temp the radiator reached.

A bit of free advice: I’ve been reading up on all the available temp+humid sensors. And while I’ve only tried the DHT22 (ok, reliable but kind of inaccurate) and BME280 (terrible self heating) I am going to try replacing them with SHT31-D sensors. Far more accurate than any other supported sensor (except the TMP117, but that does not do humidity). I say supported because the SHT85 is even better but not currently supported by ESPHome.

Check out the results in this forum: https://forum.arduino.cc/index.php?topic=624204.15

Dallas would definitely be suitible for air temps just not all in one with humidity. THey were sitting on my desk for a while next to a standard digital aprilaire thermostat and were pretty in sync.

10k resistors are/were used by many thermostat manufactures like ecobee and honeywell, in their older wired versions.

Yet again I skipped over information. Sorry, wasn’t aware you wanted this for pipe temps. The Dallas sensors are pretty much your only option (that I know of).

Here’s a walk through how to set everything up

So the main boards are


This would be the sensor


1 Like

Wemos D1 Mini

1 Like

Same size, same price, more powerful, more i/o: ESP32-mini

Since basically all answers point into the same direction (ESP + sensor) - I’ll give up the idea of finding a product that support this.

It was a long time since I built something, so I probably will need some reading time on the topic.

Thank you all for suggestion and links to point me into the right direction.

Have a look at Frenk’s doorbell tutorial for how easy ESPHome is. If you know any YAML from Home assistant you know ESPHome.

1 Like

If you want more of a off the shelf option, you could look at cooking thermometers like BBQ and smoking.

1 Like

Thanks, tempting solution. But I’m worried it will fall short. The probe is really not made to measure a water pipe. Even though I can image the BBQ enthusiasts wants to know the temperature as accurate as possible.

A contact thermometer is exactly what you want. What temperature range do you need, I’m guessing <165F (~74C). Just a little out of the box thinking; 99% the same, you just want to measure temperature in contact with a pipe instead of inside a yummy slab of meat.

Edit: I know there are threads here that utilized ESP connected thermometers for cooking.

Maybe if the wired meat probe can be replaced?

You are getting hung up on something that is irrelevant… a thermo-couple (TC) is a thermo-couple. Different ‘types’ of TC are to cover different temperature ranges, the medium it is measuring doesn’t really matter. I use the same TC in a vacuum for no contact, in a vacuum contact with metal, laser mirrors, super plastic forming presses and dies for heater control. Yes there is different sheathing on TCs for different reasons but for anything you are likely to measure <1000F (I’m assuming) then the TC are all going to be the same. Just because a manufacturer/retailer states that this is for ‘whatever’ purpose only does not make it true.

What is your definition of smart?

Another option is a soil thermometer; you have some options there to.

If you buy a BBQ thermometer, you’ll get a meat probe. Probably made out of metal and it’s a few inches long. I’m not expert in meat probes, but I think the length and the material, doesn’t really make it suitable for measuring a pipe where you have a curved metal contact area.

Anyway, I’ll probably try to find a small probe and then add some isolation on top of it to get. Connect it as suggested above and spend another 20h learning something new :slight_smile: