Best temperature and humidity sensor?
Any recommendations on the the best (combination of low cost and accuracy) temperature/humidity sensor out there?
When I changed the batteries today on my Acurite 00609SBLA1 outdoor unit, I set it next to the indoor unit to check the accuracy. They have been next to each other for about 3 hours now, and the temperatures are within 1 degree Farenheit of each other, which is accurate enough. HOWEVER, the indoor unit reads 11% higher humidity than the outdoor unit. Since they are now next to each other they should match, so one of the two is not working. I’ve already removed and replaced the batteries. If anyone has any ideas on how to fix this, I’d love to learn about that process.
If I get a new one, which one is best? Any independent tests? One that works on it’s own and also would connect to zigbee or zwave would be ideal.
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All consumer RH sensors have pretty poor accuracy. Unless you are looking to spend big $$ on a Visala calibrated unit, you'll never get much accuracy.
Your best bet is to get a couple of different units and average between them.
If there is a weather station near you, you can use that to figure out what the correct reading should be.
Accurite provides a calibration facility for their devices. I’ve never bothered to do it with mine, so I can’t say how well it actually works.
Akos is right too, cheap humidity sensors are notoriously inaccurate. I’ve actually designed some specialized networked temperature humidity sensors to monitor gradients in large facilities to allow optimization of airflow. To get reliably consistent measurements takes some careful design, and good sensors. Many humidity sensors out there aren’t really very good, or very reliable. I used one originally made by Humirel, which is apparently part of TE Sensor Solutions now. TE likes to buy other companies it seems. Anyway, the datasheet is here if you’re curious: https://www.te.com/commerce/DocumentDelivery/DDEController?Action=srchrtrv&DocNm=HPC052&DocType=DS&DocLang=English
Note that that is just the sensor element so it’s not useable for you by itself. It gives a little bit of an idea of what a good sensor needs to give good results though. These sensors are around $6 each in low quantities, and that is the sensor only with no support components. Any $10-20 consumer humidity sensor isn’t going to have this level of sensor inside.
Bill
Thanks for the info about the Acurite calibration. Turns out that is only for some models; mine is not one of them.
Any recommendations on a particular brand and/or model that is even slightly better than the competition?
The davis instruments stuff is a lot better than the cheaper stuff, but you pay for it. The Davis instruments stuff is an inexpensive (relatively) professional line of equipment. The next step up from Davis instruments is a BIG BIG price jump.
I Think Extech makes some sensors too, but they have no networking capability — their stuff is intended more for handheld measurements.
Bill