Hi,

I am using a sonoff TH20Elite to control my 150lt geysers. The temperature sensor is connected to the TH20 using the extender cable.

The TH20 has intermittent temperature reading. Is anyone else experiencing the same problem?

Regards,

 

Sorry, I can't really help that much, because my THR320 has been reflashed with ESPHome. Just curious how you are getting the water temperature? Did you just stick the sensor onto the side of the geyser?

I actually got a Geyserwise thermostat with an analogue thermistor, then had to figure out how to interface that with the THR320 which can only handle the Dallas 1-wire sensors. I ended up using an ATTiny85 to read the thermistor, and talk to the THR320 using 1-Wire. But it works really nicely now, and I'm dumping excess solar into the geyser, pushing it up to 65C when I can. Since the THR320 is reprogrammed with ESPhome, I actually have 3 presets, "Home" keeps the water around 55C, as if it were a conventional geyser, "Boost" pushes it up to 65C to soak up excess solar generation, and "Eco" drops it to 45C which works pretty well.

Just really interesting to see how quickly the temperature drops from 65C, but how it will stay at around 40C for 12 hours with no external input at all!

I have encountered the same problem that my THR320 Elite blanks out above 40 Celcius. Could it be that this smart switch had this temperature limitation?

Had same issue on my own extension cable...blanked out between roughly 28deg and 42deg....

Extension was made up of good quality UTP cable, about 15m. 

Tried many tricks to fix this, and what eventually did it was changing to STP cable! Seems the cable needs the shielding...

@Muchachos you did mention using an extension although it sounds like the original Sonoff extension? Weird, that should work..how many meters you extending?

@markus_m2 In my case I am using one length of 5 metres of the Sonoff RL560 Sensor Extension Cable with the Sonoff DS18B20 Temp Sensor. The sensor is cable tied to the geyser brass (outlet) flange.

Today again it started registering the temp as it dropped below 40 C and then went blank as the temp went over 40 C. The temp is controlled by the geyser thermostat and I only use the THR320D Smart Switch to monitor the hot water temp while it is used.

Can anybody at Sonoff confirm whether the THR320D has this temperature range limitation of 40 deg C.

 

 

@markus_m2 

Can anybody at Sonoff confirm whether the THR320D has this temperature range limitation of 40 deg 

Nope no such limitation...

I would try take the THR320D away from geyser, temp probe direct into hot mug of water. Let it cool, make sure it reads entire range.

Then, do same with the extension cable - see what difference it makes.

In my case I found the electromagnetic interference up in the roof messed with my UTP extension, as soon as I used STP cable my issue was sorted (20deg up to at least 70deg reading correctly)

My graph also disappeared like that when the device fell off the WiFi for a bit.

Hi there, has anyone conclusively found a solution to this issue. I have a situation where my sensor goes blank "----" (unknown in Home Assistant) with 100% consistently between 31-36 deg. I have used good UTP wire (upsized to reduce any resistance), and soldered all joints. Got the same results with both the original Sonoff 5m extension as my own cables. If it is likely that interference is the issue and STP is the solution, I climb up in roof and redo, but was so frustrated, I was looking at replacing with Shelley+Temp Add-On. If it was interference I would expect the failure to happen randomly, not always within the same temperature range. 

I have found this on two separate THR316D and sensors. If used with original short cable this problem was not detected. 

Would really appreciate any advice/input. 

It was super frustrating when I had this issue, but now over a year later I haven't had a single issue since replacing all with a single length of STP cable! (Roughly 15m)

Pretty sure that'll sort out your issue also. 

 

19 hours ago, markus_m2 said:

It was super frustrating when I had this issue, but now over a year later I haven't had a single issue since replacing all with a single length of STP cable! (Roughly 15m)

Pretty sure that'll sort out your issue also. 

 

Hi Markus, yip, you are correct. I climbed into the roof and replaced the extension by simply splicing in a 5m length of 1mm Cabtyre (I had no network cable around). Voila, it works perfectly in that location. To confirm my suspicions, I took the "dodgy" sensor cable to another THR on opposite end of home and subject to more interference, and it did exactly the same (cutting between 31-36 deg). If I remove the OEM extension the sensor works perfectly on it's 0.5m cable.

It is beyond logic that the OEM extension cable caused specific range failures on 3 out of 3 extension cables, but that is what I have found. I do not suggest anyone buy these RL560 5m extenders, if they want to use full range of sensor. My suspicion is the wire is too thin (thinner than sensor cable) and/or subject to interference.

Thanks again Markus, hope Sonoff upgrade this RL560 product and remove existing stocks.