Temperature too high from indoor and outdoor units

[Daniel1]

I bought two AirGradient indoor (I-9PSL-DE) and one outdoor (O-PST) units. They all give temperature readings that are too high. I have six aqara temperature sensors, an Aranet 4 and a UHoo. I put them all on a table with the air gradient sensors to check calibration. The others agree within 0.6F. The indoor AGs are 2F and 2.6F too high consistently throughout the day. Both too high and 0.6F from each other. The outdoor is about 6.5F high.

I initially set them up in Home Assistant. I saw the other forum post about setting configuration source to cloud; changing that did not change the numbers. I since added them to app.airgradient and see the same numbers there.

I turned the outdoor unit off for 20 minutes, then powered it on and the temperature came on low and then rose back up over about 15 mins.

All three say their firmware is up to date.

Is there a fix or additional debugging I should provide? Thanks.

[Altair_AirGradient]

For the outdoor unit, the higher temperature readings are due to the sensor being inside the casing and thus there not being enough airflow like the natural convection in the indoor units. The standard calibration for the outdoors applies an offset to account for this which I think is very close to the difference you’re seeing. Could you try applying the calibration formula again?

The indoor units, however, are normally be very accurate so this is unusual. I’ve seen them compared them to a reference instrument and be within 0.1 Celsius.

Could you confirm whether the units are upright (not on their side) and whether these were purchased pre-assembled or as DIY kits?

[acyphus]

I just set up my first indoor monitor and noticed the temperature reading seemed high and the humidity seems low. Mine is a DIY kit that is upright on my desk.

I only have a remote Ecobee temperature sensor to compare it to, but it seems to read around 10F higher at all times.

[Altair_AirGradient]

Hi @acyphus, Welcome to the community! The indoor monitor is typically very accurate with temperate and humidity readings. I wonder if you can use a different reference to double check, if needed?

[acyphus]

@Altair_AirGradient I don’t have anything that can provide an accurate reference. I have a probe thermometer from my kitchen, and the outdoor temperature that I can reference.

Using the outdoor temperature, in this small room when the window has been open for a few hours, the Ecobee sensor is within 1-2F of the outdoor temperature, while the AirGradient is around 10F higher than the outdoor temperature.

I’ll note, that when turning on the ceiling fan in this small room, the AirGradient temperature drops around 3F, while the Ecobee is not affected by that additional airflow.

I can also say that when the Ecobee is reading 78F and the AirGradient is ready 89F in this room, my body is not telling me that it’s 89F. I know that is anecdotal, but as someone who tends to be aware of hot stuffy rooms, I do not believe it’s 89F in the room when I see that on the display.

[MallocArray]

That looks like a Home Assistant card. Assuming you are using the HA Integration, can you try changing the Configuration Source to Cloud

This is in HA under Settings>Devices and under your individual device.

This also assumes that you registered it with the AirGradient Dashboard site, which will ensure it gets all of the appropriate correction algorithms, which the Local source doesn’t set by default.

[acyphus]

Thanks! I hadn’t set up the AirGradient dashboard, so I’ve done that and set my config to cloud. I’ll give it some time to adjust and report back

[Daniel1]

Hi Altair, somehow I missed this reply until now, sorry about that. I posted an update that answers your suggestions in the topic Struggling to get accurate temperature", sorry about the multiple posts, still figuring out the forum…

I also have a support ticket, 25792. I tried to fit a custom offset on the downloaded un-bucketed data to transform the outdoor readings to match the indoor readings. That came out at T_hack = T_raw * 1.402 - 13.856, but app.airgradient doesn’t allow offsets bigger than 10C so that is a dead end. Probably not a good approach anyway…

At 25C from the outdoor sensor the indoor sensors read about 21C. The calibration formula adds .181 * T_raw (4.5C) and subtracts 5.113C, net -0.6C. I need more like -4C. It seems like the raw temperature in the unit is much higher than expected. When I turn the O-PST off for 15 minutes and then turn it back on it heats up by 12F (6.7C). All three were purchased pre-assembled.

Thanks for any suggestions.