HiLetgo 5pcs DS18B20 Temperature Sensor Temperature Probe Stainless Steel Package Waterproof 1M

I purchased these for monitoring the temperature in my machine room and server racks. Inexpensive, easy to wire up to a USB-to-TTS dongle, Arduino, or Raspberry Pi. They work well with the DallasTemperature "OneWire" library and with the linux "digitemp" program (apt install digitemp).For accuracy, I suspended the sensor in the air, waited 30 minutes, and compared their measurements against two different physical thermometers. Each of the five digital thermometers were within 2 degrees F (1 degree C) of the physical thermometers, and all of these thermometers matched each other to within 0.5F. That's accurate enough for my own needs. (Especially since I have no direct way to measure the accuracy of the physical thermometers. For all I know, these may be more accurate.)

I got exactly what I expected. I wired them up to an ESP32 running ESPHome, and it appeared in Home Assistant immediately. Very close match to a desktop thermometer, so acceptable for my use.

One was defective and didn’t work at all. The other 4 were fine and all read with .5 degree F of each other

So easy to measure temperature with these and a Raspberry Pi computer. Only word of caution, the length of the wire is very important along with the daisy chaining of probes and the pull up resistor. My run is well under the 1000 foot limit for Dallas 1-wire circuits but until I got them wired up and found a good value for the resistor, I could not get reliable readings. My system has 7 sensors on about 500 feet of #23awg Cat-6 wire. The original 4.7k ohm resistor worked ok but would get a wired reading from time to time. Once I changed the value to 2.7k ohms, the system became very stable. One thing to note, the copper lead are very thin and hard to tin or solder too.

Using these temperature sensors to monitor the HVAC system at my home. Connecting them to a Shelly Plus Add-on/Shelly Plus 1, to ultimately integrate into Home Assistant. Which should be cool since it stores the data and can view the history or download it and view outside of HA.Once I had them configured on the Shelly Plus One, I tested them in a cup of ice water and compared them to a Therm Pro thermometer that I know to be accurate. Then placed them in pan of hot water, and again they all were pretty close to the Therm Pro thermometer. For the price they seem accurate enough and should be good enough for the what I am using them for.

The DS18B20 are giving me extremely steady readings that vary my less than 0.05 deg. I'm using them in a differential application, so I also needed them to match each other and they seem to be right on the money.

The response is slow. When the temperature changes, It can take a couple of minutes for the measurement to settle.

Bought these for monitoring my geothermal water furnace. Leads were 3ft long and ends were tinned.Sensors are sensitive for my usage.