DHT11 Inaccuracy

Support Product Questions
1

Hi Everyone

I have completed my first Raspberry Pi project last weekend. It is a Pi Zero Wireless running a DHT11 temperature/humidity sensor.

I have it set to take a reading every 5 seconds and average this out and upload to WeatherUnderground. It also has a quad alphanumeric display for local viewing.

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Basically, since I have been uploading to WeatherUnderground I notice that my neighbouring stations have around a 4-6 degree variation on my reading of temperature and the humidity is way off sometimes by a factor of 2.

I have also placed an Oregon Scientific BAR218HG next to it and observed this same behaviour. I’m starting to think the DHT11 sensor I have may be faulty.

I have my setup outside, in constant shade (under the patio) which to my understanding is typically where a thermometer type setup would be placed (rather than in direct sunlight).

Any suggestions?

Cheers
Kevin

2

Hi Kevin,

DHT11’s can be a little hit and miss from what I’ve found. The newer DHT22’s are quite the leap forward.

If you have other devices using DHT11’s, I guess you could swap them around to cross-check your readings?

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3

It looks like its somehow come good over the last week. We had a couple of pretty hot days there. I’m wondering if it somehow calibrated itself off that? Anyway it seems to be giving pretty accurate readings currently so I’m happy. Thanks all.

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