Forum Sensor.Community

Two very different T° on Nettigo Air Monitor 0.3?

I recently installed this kit, and I see there are actually two different temperature measurements tracked, that can be seen here.
I suspect this ‘redundancy’ is due to the presence of two sensors for T measurement, but my concern is these temperatures are quite different, and sometimes very different during the day (like, 4° difference).
My sensor is reasonably protected from the sun, as can be seen here, although it is quite low on the ground (the wooden box opening is oriented towards a wall, so there is never direct sun there).
Still, can this large T difference just be due to sun exposition somehow?
Or did I mount the kit wrong, for instance?
I can say I lef the red sensors in that image within the box : perhaps I should have put it also in the small grey enclosure that already contains its small square neighbor?

TIA for any advice!

The electronics will produce some heat, so yes, the air inside the box is warmer than those outside. Additional the heater will warm up the air at high humidity by some degrees. This heated air will also flow trough the box.

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Thank you @ricki-z , but do I understand correctly that the red sensor (which is almost at the top of the box in my mounting) should be placed outside?

(Also I am a bit skeptical that electronics heating causes 4° difference during day, and only 0.3° at night?)

My only purpose is to avoid posting wrong temperature readings…

Thank you in any case for this super fast answer !

I think the answer is in the product description, unfortunately of the kit (2155). It says the sht31 shall be placed outside (for proper temperature and humidity) whereas the bmp180 shall be placed inside, as the pressure inside is the same as outside. However, the bmp also measures temperature, which most likely will not be the value you are interested in. As long as the NAM firmware uploads the bmp180 temperature I would try to place it outside, next to the sht31. In my NAM kit I’m using sht35 and bme280 next to each other with very similar readings.


Thank you @nephilim for this very clear answer!
So, now my only concern will be how to get both sensors inside the relatively small enclosure ‘designed’ for only one of them…
Among others, I’m not really sure I’ll manage to slide a second connector through the inner access hole while the wires from the first one are already there. (see this image from the assembly instructions to understand what I mean)
Maybe I’ll create another hole, but I have to think about it…

Also, this confirms the fact that the air sensed by the baseline T sensor actually is the output of the PM sensor, which is thus more or less heated by the device itself.

If and when I manage to put the second T sensor out, I’m considering sealing the passage to these T sensors, and piercing instead a small venting hole directly in the structure for the ‘heated inner air’.

Now, once solved this ‘dual’ temperature will become interesting, as basically it shows the uncertainty range from the sensing…

Thank you again!

You can use a thin needle to get the metal connectors out of the plastic plug. There is a clip, either on the connector or the plug which needs to be lifted carefully to unlock the connector. Make sure to write down the colours and their order relative to the plug before disconnecting. You can then guide the wires through the hole easily.

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BMP180 is meant to be used inside of case of KIT-2159. Placing them (BMP and SHT) inside external case is possible for kit to solder:

NAM (KIT-2159) is soldered with SHT31 and BMP180 on two cables, we wasn’t sure company doing soldering will do it properly when we sent kits to solder to them, so we have chosen safe version - SHT31 inside external housing and BMP180, just for pressure inside case. This is why it is inside shrink tube, to prevent anty shorts.

With next firmware release there will be checkbox for BMP180 inside case. When enabled it won’t send any temperature from BMP180 to APIs.


Thank you @netmaniac !
So basically, thanks to you I just have to wait :slight_smile:

New release (NAMF-2020-41) is out and You can configure sensor to not send temperature readings from BMP180 inside case.

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Thank you! i found the time to do it, and it seems to work perfectly!

@netmaniac , indeed the second T reading (wrong because inside the casing) is cancelled when I select to cancel it, but this setting then also cancels the pressure reading, so it’s actually as if I had no BMP180 at all if I do this…
For now I just reactivated it…

Thank You, let me check it.