In the helper configuration menu I can find how to create the SUM of 2 temperature sensors.
Is it possible to create a “difference” sensor as well?
Additional question: (where) can I find helpers in the HA files?
Try with “Statistical Range”
It’s an entity, look under entities, and it “Entities” are “stored” in the “core.entity_registry” file ( Don’t !!! edit this file unless you are knowing what you a doing )
Thanks for answering. Can you please be a bit more specific? Thx.
Range is the distance between the smallest and largest numbers in a data set (set of numerical values)
The difference between the maximum and minimum temperature is called the range of temperature
( i.e the difference between 17 and 10 is 7 in degree , the range is 7 ) = Using the " statistical-range "
( the Sum = 27)
( i.e the difference between 10 and 17 is 7 , in degree, the range is 7 ) = Using the " statistical-range "
( the Sum = 27)I
( i.e the difference between 17 and -10 is 27 in degrees , the range is 27 ) = Using the " statistical-range "
( the Sum = 7)
( i.e the difference between -10 and 17 is 27 , in degrees, the range is 27 ) = Using the " statistical-range "
( the Sum = 7)I
If you pour 1 liter of fluid with a temperature of -10 in a bowl, together with 1 liter of fluid with the temperature +17, you wont get an exact (sum=7) , but you will have 2 liters of fluid with a (mean) of the 2 states/values, 
And would you never get 27( the Range between the 2 )
You would however have a bowl of 2 liters fluid, with a temperature around Mean
You really mean it should be more Specific here also ? , Or don’t you know where to create a Helper(entity) ?
A Helper is An Entity, found under “Entities” just to the left of " Helpers "
I Prefer not to go into further details in regards to the “core.entity_registry” file
This helps a lot. Although I had education in these kind of topics, I don’t know (anymore?) what they exacly mean… But now I do! You made me happy!
Thanks a bunch!