Temperature just switched from C to F - why?

riz94107 · June 21, 2018, 6:42pm

I’ve been using home assistant for a few weeks, and I’m still getting the hang of things. I have a couple temperature sensors that i’ve been tweaking settings for, and I had just changed them this morning (a few hours ago) so that the values were float(), hoping that would allow the graphs to do what I wanted. This seemed to work OK.

However, when I changed my test graph from the last 2 hours to the last 24h, both my sensors suddenly started reporting in Fahrenheit instead of Celsius - but didn’t convert all the old values. So, my graphs look like this:

13%20AM

The sensors themselves report in C (I checked the actual MQTT output), they’re labeled as C in the configuration, and they’ve been happily reporting C for days. Suddenly, this change, and I don’t understand it. I am in the US, and my defaults are imperial, but I certainly didn’t change this in the last few minutes. Anyone have any thoughts?

Here’s the sensor config:

sensor:
  - platform: plex
  - platform: mqtt
    name: livingroom_temperature
    state_topic: "livingroom/sonoff/tele/SENSOR"
    unit_of_measurement: "°C"
    value_template: '{{ float(value_json.DS18B20.Temperature) }}'
  - platform: mqtt
    name: basement_temperature
    state_topic: "basement/sonoff/tele/SENSOR"
    unit_of_measurement: "°C"
    value_template: '{{ float(value_json.DS18B20.Temperature) }}'

…and here’s the graph section, which I just changed:

history_graph:
  gr1:
    name: Temperature
    entities:
      - sensor.livingroom_temperature
      - sensor.basement_temperature
    hours_to_show: 168
  gr2:
    name: temperature_24
    entities:
      - sensor.livingroom_temperature
      - sensor.basement_temperature
    hours_to_show: 24

recorder:
  include:
    domains:
      - sensor
      - switch
      - light

petro · June 21, 2018, 8:28pm

temperature units are global in home assistant. If you specify a sensor with a given unit, home assistant will convert it to the global unit in the user interface.

To change your global unit, see here:

riz94107 · June 21, 2018, 10:16pm

OK, so THAT’S why it picked that moment to change - because I set the units of the sensor. A little confusing, but I suppose I can live with it.

Thanks!

petro · June 21, 2018, 11:12pm

yah, annoying but that’s why it does that. Makes sense, especially if you work in one unit.

TimothyLeeAdams · September 26, 2018, 8:34pm

@riz94107 I’m curious, were you able to get your graph to display the correct temperature unit? In your graph, the values are graphed at their converted °F values, but the graph still indicates °C as the unit. I have the same behavior with a very similar setup and it’s driving me crazy because I can’t get a combined graph of all my temperatures working. The issue seems to be that some of my sensors report in °F and some report in °C. The unit_of_measurement field on each sensor is set accordingly to its native reporting unit in my sensor config, and my global unit_system is imperial.

- platform: mqtt
  name: "Sonoff MQTT Bathroom Temperature"
  state_topic: "tele/sonoff_bathroom_fan/SENSOR"
  value_template: '{{ value_json["DHT11"]["Temperature"] }}'
  unit_of_measurement: "°F"

- platform: template
  sensors:
    kitchen_temperature:
      friendly_name: 'Kitchen temperature'
      value_template: '{{states.sensor.kitchen_motion_sensor.attributes.temperature}}'
      unit_of_measurement: °C
    living_room_temperature:
      friendly_name: 'Living room temperature'
      value_template: '{{states.sensor.living_room_motion_sensor.attributes.temperature}}'
      unit_of_measurement: °C
    bedroom_temperature:
      friendly_name: 'Bedroom temperature'
      value_template: '{{states.sensor.bedroom_motion_sensor.attributes.temperature}}'
      unit_of_measurement: °C
    bathroom_temperature:
      friendly_name: 'Bathroom temperature'
      value_template: '{{states.sensor.bathroom_motion_sensor.attributes.temperature}}'
      unit_of_measurement: °C

What I end up with in my graph display group is split into 2 graphs:

Any idea what the correct config would be to get them all displaying in °F and in the same graph table?

petro · September 26, 2018, 8:42pm

Try overriding the unit_of_measurement inside the customize section, leaving the unit_of_measurement in your template sensors as is.

TimothyLeeAdams · September 26, 2018, 9:26pm

Ahhh, good idea! I tried overriding the sensors in the customize section, which allows the sensors to merge and displays °F as the unit, but it inverts the values on the graph for those sensors to °C

customize:
  sensor.kitchen_temperature:
    unit_of_measurement: °F
  sensor.bathroom_temperature:
    unit_of_measurement: °F
  sensor.living_room_temperature:
    unit_of_measurement: °F
  sensor.bedroom_temperature:
    unit_of_measurement: °F

Home_Assistant

Maybe overriding the unit_of_measurement on the group the sensors are in or the history_graph itself is the way to go?

TimothyLeeAdams · September 26, 2018, 11:41pm

I ended up just having to give up on using the native °C unit, and instead used a conversion formula in the template and set the unit_of_measurement to °F

 kitchen_temperature:
  friendly_name: 'Kitchen temperature'
  value_template: '{{ (((states.sensor.kitchen_motion_sensor.attributes.temperature) * 9 / 5) + 32) | round(1) }}'
  unit_of_measurement: °F

I also had to clear the history for these sensors in my database to clear it of any references to the old units.
Now I just need to figure out why this little DHT11 temperature sensor is so inaccurate

Home_Assistant

petro · September 27, 2018, 3:41am

Sorry I didn’t get back to you sooner. To me, that sounds like a bug. It should be displaying ºF when you use the ºC as the unit and your config is set to ºF. Glad you got it fixed though.

TimothyLeeAdams · September 28, 2018, 12:32am

No worries! I knew I could always value template it, but I was really trying to figure out if I was doing something incorrectly or if it was indeed a bug, as that’s what I was starting to suspect because the ºF unit_of_measurement was being correctly passed on my other UI elements. Thanks again.

pnbruckner · September 28, 2018, 1:23am

So this sounds like something I’ve been experiencing on and off for quite some time. I have several sensors that are all in °F, and have a unit_of_measurement of °F, yet when once in a while I delete my database and restart HA (for various testing reasons), one of the sensors shows separately in a graph labeled °C, again, even though the values are °F and the unit_of_measurement is °F. It looks like this:

It will stay this way for a while (like maybe a few days or so), then presto-magico, one day I’ll look and they’re merged together on a single °F graph! This has happened at least four or five times over the last few months.

FWIW, here they are on the States page:

And I have unit_system: imperial in configuration.yaml.

petro · September 28, 2018, 3:10am

There is some goofyness with this for sure. To me it seems like an unreported bug. Not many people are going to have mix and match senor units.

pnbruckner · September 28, 2018, 3:30am

Agreed. I just haven’t gotten around to investigating or doing anything else about it because, as I said, before long it somehow corrects itself (for me, at least) and then works just fine until the next time I blow away my database.

pprovost · January 7, 2019, 7:20pm

I understand why you’d want to convert for most sensor values, but some are meant to be reasoned over in their original units. I do all of my 3D printer stuff in °C, but track my house in °F.

Here’s where it gets messy…

I am using InfluxDB and Grafana, and once Hass makes the switch °C to °F, it starts submitting it on that measurement name to Influx.

I think the Influx component should NOT convert the values, but send them as specified in the component.

Ryan_Grandy · March 30, 2019, 1:29am

Did you figure this out since this post? I am having the same exact issue. Its pretty annoying.

pnbruckner · March 30, 2019, 5:04pm

Nope, I haven’t. Still happens from time to time.

soumya92 · April 9, 2019, 5:38am

Happens to me too. Just had two of my motion sensors jump to a new graph (marked C, but still showing values in the F range: 65-75).

I just realised that these are sensors that recently became unavailable, so I had to reboot them (battery disconnect/reconnect). Oddly enough, four sensors went offline today, but two of them are now back in the F graph, while two are on the C graph.

Craig_Poulton · July 6, 2019, 6:41pm

This is an old thread, but I think it should be considered a bug if we can’t override the global setting.

petro · July 6, 2019, 7:05pm

Just because something behaves differently than you expect does not make it a bug. You’re welcome to add a feature request. But this is certainly not a bug, it’s by design.

pnbruckner · July 6, 2019, 8:28pm

I think this topic has talked about different but related issues. The one that seems clearly like a bug is displaying a sensor, whose unit_of_measurement is, and always has been, F, on a graph where the Y axis is labeled C, yet the values are also clearly F. And then sometime later, the same sensor jumps to a graph where the Y axis is labeled F. That is certainly a bug.