I agree that the Sense “How To” on this could use some more details and consolidation:
To answer your questions:
- Merging is immediate. The Stats are re-computed “quickly” and will be updated.
- Un-merging (as mentioned above) is likewise immediate.
- Merging order doesn’t matter … but you cannot merge two separately merged groups of devices together, as mentioned here:
https://help.sense.com/hc/en-us/articles/360013253534-Web-App-v6
- A fridge light is perhaps the best example of Pros/Cons: If you merge the light and other fridge components you’ll loose the ability to set notifications based on the Fridge Light device and also the immediacy, in the Device stats of being able to see how many times the light was activated = number of times the fridge door has been opened!
Something to note here (and that could perhaps also be detailed in some refinements to the Sense support docs on merging) is that when you export data you’ll see that the .csv file will reflect the merged devices. i.e. the individual device data will not be listed. It seems that “regular” (unmerged) devices are given hexadecimal ID’s and merged ones use IDs starting with >“f” and <“m”? I believe this is so the order of devices vs “mains”/“solar”/“always_on” in the DeviceID field is kept clustered alphabetically. Hue light devices, for example, are given an ID starting with “z” (from what I understand) because they are a separate class of device.