# Compare temperature between two TH16

**URL:** <https://forum.ewelink.cc/t/compare-temperature-between-two-th16/8815>\
**Category:** Free discussion\
**Tags:** scene\
**Created:** [November 20, 2022, 3:15pm UTC](https://forum.ewelink.cc/t/compare-temperature-between-two-th16/8815 "2022-11-20T15:15:26Z")\
**Posts on this page:** 20\
**Page:** 1

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**Author:** ![alexandre47](https://avatars.discourse-cdn.com/v4/letter/a/a9a28c/32.png) [@alexandre47](https://forum.ewelink.cc/u/alexandre47)\
**Post date:** [November 20, 2022, 3:15pm UTC](https://forum.ewelink.cc/t/compare-temperature-between-two-th16/8815/1 "2022-11-20T15:15:26Z")

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I have 2 TH16s with a temperature sensor. Can I create a scene where I compare the temperature between the 2 TH16s and activate 1 of them if the temperature of the second is higher? I couldn’t do it. Any suggestions, ideas?

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**Author:** ![yitie](https://dub1.discourse-cdn.com/flex005/user_avatar/forum.ewelink.cc/yitie/32/3613_2.png) [@yitie](https://forum.ewelink.cc/u/yitie)\
**Post date:** [November 21, 2022, 2:28am UTC](https://forum.ewelink.cc/t/compare-temperature-between-two-th16/8815/2 "2022-11-21T02:28:54Z")

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NOT for now, the compared temperature is the one that the sensor monitored of ambient, not from other devices.

Would you please let us know why you have this feature request? Will evaluate it deeper.

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<div class="post-metadata">

**Author:** ![alexandre47](https://avatars.discourse-cdn.com/v4/letter/a/a9a28c/32.png) [@alexandre47](https://forum.ewelink.cc/u/alexandre47)\
**Post date:** [November 21, 2022, 3:08pm UTC](https://forum.ewelink.cc/t/compare-temperature-between-two-th16/8815/3 "2022-11-21T15:08:48Z")

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```auto
I have a water heating system where I have a temperature sensor connected to 1 TH16 in the solar collector and another temperature sensor connected to the second TH16 inside the hot water box.
I need every 1 minute to check the temperature of the collector sensor and if the temperature of this sensor is higher than that of the box, then I activate the TH16 of the water tank and otherwise I turn off the TH16 of the water tank.

```

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<div class="post-metadata">

**Author:** ![yitie](https://dub1.discourse-cdn.com/flex005/user_avatar/forum.ewelink.cc/yitie/32/3613_2.png) [@yitie](https://forum.ewelink.cc/u/yitie)\
**Post date:** [November 25, 2022, 3:30am UTC](https://forum.ewelink.cc/t/compare-temperature-between-two-th16/8815/4 "2022-11-25T03:30:28Z")

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I think we should evaluate this feature, @natalia.long please add this request to the scenes feature request list.

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**Author:** ![craigcbos](https://avatars.discourse-cdn.com/v4/letter/c/919ad9/32.png) [@craigcbos](https://forum.ewelink.cc/u/craigcbos)\
**Post date:** [November 27, 2022, 12:31pm UTC](https://forum.ewelink.cc/t/compare-temperature-between-two-th16/8815/5 "2022-11-27T12:31:41Z")

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Hi there, @yitie , I have exactly the same requirement for controller a pump from a hot water panel.  
Would be very keen to see this feature added.

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**Author:** ![jumpjack](https://avatars.discourse-cdn.com/v4/letter/j/f05b48/32.png) [@jumpjack](https://forum.ewelink.cc/u/jumpjack)\
**Post date:** [December 1, 2022, 8:44am UTC](https://forum.ewelink.cc/t/compare-temperature-between-two-th16/8815/6 "2022-12-01T08:44:29Z")

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I have a similar request, but for power: switch off one Sonoff, which is powering one appliance, if another Sonoff, which is powering whole house, detetcs over-power.

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**Author:** ![yitie](https://dub1.discourse-cdn.com/flex005/user_avatar/forum.ewelink.cc/yitie/32/3613_2.png) [@yitie](https://forum.ewelink.cc/u/yitie)\
**Post date:** [December 9, 2022, 7:05am UTC](https://forum.ewelink.cc/t/compare-temperature-between-two-th16/8815/7 "2022-12-09T07:05:21Z")

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i think this is already supported in the scene and OPS, set OPS for the POW which monitoring the whole house first, then set the scene like if POW(whole house) off, then POW(one appliance) off.

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<div class="post-metadata">

**Author:** ![yitie](https://dub1.discourse-cdn.com/flex005/user_avatar/forum.ewelink.cc/yitie/32/3613_2.png) [@yitie](https://forum.ewelink.cc/u/yitie)\
**Post date:** [December 9, 2022, 7:06am UTC](https://forum.ewelink.cc/t/compare-temperature-between-two-th16/8815/8 "2022-12-09T07:06:33Z")

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OPS feature for POW series devices [eWeLink app feature: Overload Protection System settings #smarthome #shorts - YouTube](https://www.youtube.com/watch?v=KGilZlMxBEI)

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**Author:** ![alexandre47](https://avatars.discourse-cdn.com/v4/letter/a/a9a28c/32.png) [@alexandre47](https://forum.ewelink.cc/u/alexandre47)\
**Post date:** [December 9, 2022, 11:19am UTC](https://forum.ewelink.cc/t/compare-temperature-between-two-th16/8815/9 "2022-12-09T11:19:34Z")

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Thanks to contribute, but i dont have this device. And the TH16 unfortunately dont have this OPS.

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**Author:** ![clevertonh](https://avatars.discourse-cdn.com/v4/letter/c/5e9695/32.png) [@clevertonh](https://forum.ewelink.cc/u/clevertonh)\
**Post date:** [December 15, 2022, 4:00pm UTC](https://forum.ewelink.cc/t/compare-temperature-between-two-th16/8815/10 "2022-12-15T16:00:39Z")

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I have solar heating for a pool, where I have a sensor on the solar panel and another on the pool. I want to turn on the pool motor, only if the plate temperature is higher than the pool water and the pool temperature is not at the desired temperature.

**Scene example:**

Sensor 1 - Pool

Sensor 2 - Solar plate

**IF**

[Sensor 2] \> [Sensor 1]

AND [Sensor 1] \< 32°

**THEN**

start the engine

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<div class="post-metadata">

**Author:** ![yitie](https://dub1.discourse-cdn.com/flex005/user_avatar/forum.ewelink.cc/yitie/32/3613_2.png) [@yitie](https://forum.ewelink.cc/u/yitie)\
**Post date:** [December 19, 2022, 2:21am UTC](https://forum.ewelink.cc/t/compare-temperature-between-two-th16/8815/11 "2022-12-19T02:21:49Z")

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This featute is on the working on list now, and planned available in next 2-3 versions.

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<div class="post-metadata">

**Author:** ![alexandre47](https://avatars.discourse-cdn.com/v4/letter/a/a9a28c/32.png) [@alexandre47](https://forum.ewelink.cc/u/alexandre47)\
**Post date:** [December 19, 2022, 2:41pm UTC](https://forum.ewelink.cc/t/compare-temperature-between-two-th16/8815/12 "2022-12-19T14:41:23Z")

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this is a very good news. I hope it work as soon as possible. It will help me a lot

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**Author:** ![DJackCZ](https://avatars.discourse-cdn.com/v4/letter/d/a5b964/32.png) [@DJackCZ](https://forum.ewelink.cc/u/DJackCZ)\
**Post date:** [January 8, 2023, 10:47pm UTC](https://forum.ewelink.cc/t/compare-temperature-between-two-th16/8815/13 "2023-01-08T22:47:43Z")

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Just as ‘clevertonh’ states, it would switch very often even with a temperature difference of 0.1°C. It would be better to be able to set the hysteresis between the sensors by a certain number of degrees. Then the scene (or the Automatic mode in the APP) for turning on the pump if the temperature on the solar exceeds the set hysteresis value (without checking the water in the pool to see if it is warmer than 32°C) could look like this:  
WHEN  
temperature TH1x(Solar) - 6°C \> temperature TH1x(Pool)  
THEN  
pump = ON

and the second shutdown scene:  
IF  
temperature TH1x(Solar) - 1°C \< TH1x(Pool)  
THEN  
pump = OFF

This is how it would switch on when the temperature on the solar panel warms up by more than the set 6°C and the pump would turn off when the solar panel cools down to a temperature 1°C higher than the water in the pool, otherwise it would take a long time to turn off the pump at high temperatures .

P.S.: This is how I currently use it, with only one TH1x on the solar system, I use the Automatic mode directly in the APP for the device, which I set in the morning according to the current temperature in the pool (24°C), but in this manually set/automated switch-on mode by more than 9°C i.e. at 33°C and switching off by more than 4°C at 28°C. And anyway, at high outdoor temperatures, I usually have to adjust the values 1-2 times during the day, because with such a fixed temperature in the morning, the pump no longer switches off in the afternoon if the temperature in the pool warms up above this set switch-off temperature.

If it can be done this way (comparing the temperatures from two devices and also with the hysteresis), then I would use it immediately and in the next case in the winter to start the fan for air exchange, when the temperature in the garage is lower than the current outside temperature during the day and then again in the summer on the contrary to cool down the garage at night 🙂

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<div class="post-metadata">

**Author:** ![kevinmmurphy](https://avatars.discourse-cdn.com/v4/letter/k/e5b9ba/32.png) [@kevinmmurphy](https://forum.ewelink.cc/u/kevinmmurphy)\
**Post date:** [January 15, 2023, 10:10pm UTC](https://forum.ewelink.cc/t/compare-temperature-between-two-th16/8815/14 "2023-01-15T22:10:48Z")

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I have 2 use cases.

All controlled by Th16

In winter this helps me control ice dams in the garage and in the summer makes the garage more comfortable.  
If garage temp \> outdoor temp turn on power vent.

I also have a pool and want to turn on the pool pum when water in solar panel \> pool water temp.

I woulg also want to have this capability to turn on a whole house fan if the house temp \> outdoor temp (within parameters).

Home automation becomes useful when it can make life more comfortable and save energy and money. Enough with controling lights and music.

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<div class="post-metadata">

**Author:** ![alexandre47](https://avatars.discourse-cdn.com/v4/letter/a/a9a28c/32.png) [@alexandre47](https://forum.ewelink.cc/u/alexandre47)\
**Post date:** [January 16, 2023, 1:14pm UTC](https://forum.ewelink.cc/t/compare-temperature-between-two-th16/8815/15 "2023-01-16T13:14:18Z")

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I solved it by installing Home Assistant on a raspberry pi. Home Assistant allows you to carry out any type of automation.  
With Home Assistant I was able to do an automation comparing when a sensor is bigger than the other or smaller and many other possibilities. The possibilities are endless

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**Author:** ![fennerinium](https://avatars.discourse-cdn.com/v4/letter/f/54ee81/32.png) [@fennerinium](https://forum.ewelink.cc/u/fennerinium)\
**Post date:** [March 26, 2023, 5:28am UTC](https://forum.ewelink.cc/t/compare-temperature-between-two-th16/8815/16 "2023-03-26T05:28:59Z")

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Do you know if this feature has been released yet? I plan to purchase two temperature sensors with the hope to control a scene based on both read outs. Would be nice to know if the feature exists before buying the hardware.

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<div class="post-metadata">

**Author:** ![DJackCZ](https://avatars.discourse-cdn.com/v4/letter/d/a5b964/32.png) [@DJackCZ](https://forum.ewelink.cc/u/DJackCZ)\
**Post date:** [April 2, 2023, 10:51pm UTC](https://forum.ewelink.cc/t/compare-temperature-between-two-th16/8815/17 "2023-04-02T22:51:28Z")

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Unfortunately, I still don’t know about this function, or I just haven’t found a way to do it, but more and more I’m also thinking about switching to Home Assistant, which I’m currently deterred by flash firmware on many devices, and currently the impossibility of buying an RPi 3B+. But the benefits would probably be significant. Improved control options and the ability to save all logs about door opening and closing, device switching on and off, temperature or humidity recording at a set interval, or just when the temperature changes … which is now not possible directly from eWelink, probably only using paid version of IFTTT and I still don’t know how.

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<div class="post-metadata">

**Author:** ![PeterGoGo](https://dub1.discourse-cdn.com/flex005/user_avatar/forum.ewelink.cc/petergogo/32/460_2.png) [@PeterGoGo](https://forum.ewelink.cc/u/PeterGoGo)\
**Post date:** [April 4, 2023, 7:36am UTC](https://forum.ewelink.cc/t/compare-temperature-between-two-th16/8815/18 "2023-04-04T07:36:29Z")

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Hey guys, here is the latest update of the compare temperature feature.  
We’ve worked out the first version of this feature, however, our team is not that satisfied with it and we came up with a new version. We expect to bring it out in June or July. Thanks for your suggestions and patience.

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<div class="post-metadata">

**Author:** ![fennerinium](https://avatars.discourse-cdn.com/v4/letter/f/54ee81/32.png) [@fennerinium](https://forum.ewelink.cc/u/fennerinium)\
**Post date:** [May 17, 2023, 2:58am UTC](https://forum.ewelink.cc/t/compare-temperature-between-two-th16/8815/19 "2023-05-17T02:58:40Z")

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Thanks for working on this feature and keeping us updated on the progress.

In the meantime, I came up with a temporary workaround, but it’s led to more questions than answers.

I have two manual scenes called “pool mode” and “spa mode”.  
I have auto scenes for temperature control:  
“pool is cold” if temp is \<=85, turn relay off  
“pool is hot” if temp is \>=86, turn relay on  
“spa is cold” if temp is \<=100, turn relay off  
“spa is hot” if temp is \>=101, turn relay on

Manual scene “pool mode” enables auto scene “pool is cold” and “pool is hot” and disables “spa is cold” and “spa is hot”. The inverse is true for manual scene “spa mode”.

Here’s my observed phenomenon. If manual scene “pool mode” is run, and after some time, the temperature increases above 86, auto scene “pool is hot” will trigger and turn on its relay (as expected, that part is good). If I then manually run “spa mode”, the auto scene “spa is cold” does not trigger and the relay is not turned off (even though the temperature is well below the 100 setpoint). Keep in mind that auto scenes “pool is cold” and “pool is hot” are disabled when I enter “spa mode” so I don’t think that’s conflicting.

My theory is that because the temperature is already below the “spa is cold” threshold when the scene is enabled, it doesn’t act on it. But if the temperature actively crossed the threshold, then it would register it as a trigger. Is this a firmware bug? Or am I missing some piece of logic? Tomorrow I plan to add a 1 minute delay between the disabling of “pool is cold/hot” and the enabling of “spa is cold/hot” in case that single action of disabling and enabling is causing it to conflict for that instant.

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<div class="post-metadata">

**Author:** ![PeterGoGo](https://dub1.discourse-cdn.com/flex005/user_avatar/forum.ewelink.cc/petergogo/32/460_2.png) [@PeterGoGo](https://forum.ewelink.cc/u/PeterGoGo)\
**Post date:** [May 17, 2023, 8:51am UTC](https://forum.ewelink.cc/t/compare-temperature-between-two-th16/8815/20 "2023-05-17T08:51:36Z")

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Hi there, actually this is something that is closely related to the trigger mechanism of the TH device in Scene.

You have created the auto scenes and manual scenes.  
In the first scene, “pool is cold”: when the temp is lower than 85, the relay is turned off. The scene works because the temp drops to 85. However, the scene “pool is hot” works only when the temp rises from lower than 86(let’s say 85.6) to higher than 86. In other words, if the temp goes up from 86 to 89 or whatever, the scene “pool is hot” will not be triggered.

Similarly, in the next two scenes, if the temp is already lower than 100, then the relay will not be turned off. This scene will be triggered and executed only when the temp drops from let’s say 103 to 100.

[Next page](https://forum.ewelink.cc/t/compare-temperature-between-two-th16/8815.md?page=2)