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Getting very inaccurate temperature readings

Open TheFitzZZ opened this issue 8 years ago • 9 comments

Hey guys,

I have six of the sensors around the house, some also where already other sensors exist, so I can compare the results. Something I don't really need another sensor for is the fact, that the remperature is off by some extend. It's always way too high by 5-10°C - same error with °F btw.

Any ideas what could cause this? It makes them practially useless.

Thanks

TheFitzZZ avatar May 28 '17 08:05 TheFitzZZ

Do you by any chance have DHT11 rather than DHT22

tariquesani avatar May 28 '17 08:05 tariquesani

No, but I think I see the issue now: the case (the 3D printable one included here). I think it heats itself up and the ventilation by the few left-outs isn't enough by any chance to get proper readings.

How I know this? I aimed a little USB ventilator at the box to get some airflow. And voila, the temperature seems much more likely to be correct: went from 31°C to 24° - which seems reasonable.

I will verify further, design a new case and make a pull request for it once I've tested it ... will take some time though :-)

TheFitzZZ avatar May 28 '17 09:05 TheFitzZZ

Yeah, in doing some testing with this tonight. It does appear that the case is causing the heating issues. Sorry about that! You could add an offset in the code, but that's not a great solution. I'm going to redesign the case and move the sensor further from the board. That should help.

@TheFitzZZ, if you come up with a new case design, too. I'd be happy to post the link or host the STL in the repo if you want!

Cheers!

bruhautomation avatar May 29 '17 23:05 bruhautomation

Hi I am using dht11 sensor. it shows temprature 987 c and humidity 1098%. Can you help me out to fix this issue? Thanks

gillrishi avatar May 30 '17 10:05 gillrishi

@gillrishi get a dht22

tariquesani avatar May 30 '17 10:05 tariquesani

Ok.. Thanks for your help

gillrishi avatar May 30 '17 11:05 gillrishi

Yeah DHT11 sensors aren't as great. If you use a DHT11, make sure you set line 73 to

#define DHTTYPE   DHT11

Cheers!

bruhautomation avatar Jun 02 '17 02:06 bruhautomation

Looks like the V2 case might be doing something similar though. i'm getting about 5C difference even on the new case.

cbrherms avatar Dec 03 '17 18:12 cbrherms

Same here, its related to the case (I'm using a custom one, but still with the sonsor attached outside to the case). Having the sensor some cm away from the encasing shows me the correct temp.

Any ideas what we can do about this?

martinjuhasz avatar Jan 09 '18 15:01 martinjuhasz