The system itself
Three instincts point inwards, at Sensa rather than at the van. They are the ones that keep the others honest.
One of them watches the Sensa unit's own hardware, and it only appears on a Sensa appliance, the unit we supply. If you are running Sensa on your own Home Assistant we have no way to read the temperature of a machine we did not build, so it sits under Unavailable and stays there.
Sensor gone quiet
The instinct that guards the others. A wireless sensor running on a coin cell does not announce that its battery has died, it simply stops reporting, and every instinct relying on it quietly stops watching too. This one notices, and names the sensor that went quiet.
It covers every environment temperature sensor in the van. It deliberately does not fire at start-up, because everything wireless is briefly unreachable while the system boots, and it checks once an hour as a backstop so a sensor that died while the van was powered down is still caught.
Settings: Quiet for 30 min, range 10 to 240, in steps of 5.
Default: Alert.
You need: at least one wireless environment sensor.
Core temperature
The Sensa unit watching its own temperature, and doing something about it if nobody else can.
A unit working as hard as it possibly can settles at about 60°C with its fan running. That is normal, and it will happily sit there all day. So anything meaningfully above that is not the unit being busy, it is something restricting its cooling: a blocked vent, a fan that has stopped, or a cupboard with no air getting into it.
This instinct has three levels rather than a Warn or Alert choice.
- Warn at 65°C. Above anything the unit reaches under load, so it is worth a look, but nothing is at risk yet.
- Alert at 80°C. The point where the unit starts deliberately slowing itself down to cope, so you are now losing performance.
- Shut down at 95°C. A last resort, described below.
If you set the three out of order, Sensa quietly sorts them, so the shutdown can never end up below the warning.
At 95°C the unit powers itself off properly and stays off until you switch it back on. Everything Sensa controls goes with it: heating, alarms, tracking and the screens.
That sounds drastic, and it is meant to be a last resort. It exists because the hardware will cut its own power at 110°C regardless, without shutting anything down cleanly first, and an abrupt cut like that is how memory cards get corrupted. Shutting down properly a little earlier turns a possible dead unit into a cool-down and a restart.
You should never see it. It is roughly 35°C above where a healthy unit sits under full load, so reaching it means the cooling has genuinely failed. If you would rather it never happened, you can raise the level or switch the instinct off, but do check the fan first.
Settings: Warn above 65°C, range 50 to 90. Alert above 80°C, range 60 to 100. Shut down above 95°C, range 85 to 105. These three are always in °C, even if you have set the rest of your system to °F, because they describe the hardware rather than the weather.
Default: all three levels, as described above. There is no Warn or Alert chooser on this one.
You need: a Sensa appliance.
Core storage space
Sensa keeping its own house in order. It watches its storage and says something long before running out could become your problem.
This is the one instinct with two fixed levels instead of a Warn or Alert choice. It warns at the first threshold and raises a full alarm at the second. If you set the two the wrong way round, Sensa quietly puts them back in order so the alarm can never sit below the warning.
Settings: Warn above 80%, range 50 to 95. Alert above 90%, range 60 to 99.
Default: both levels, as described above. There is no Warn or Alert chooser on this one.
You need: nothing. This instinct is available on every system.