WHY the data of MHZ19B 200ppm less than Senseair s8 0053

[halli]

hello,everyone,I am a freshman of EASYESP.
I buy MHZ19B and Senseair s8 0053,connet them to two ESP8266 nodemcu,which firmware is ESP_Easy_mega-20181125_normal_ESP8266_4096.bin
Disable the ABC for MHZ19B, and calibration it manually（Reference to official documents）。
But the data from the two sensor is Big difference，please see the attachment png。
I test serval days ，the result is the same, WHY? which one is Inaccurate? how to finger out ?

[grovkillen]

How long have they been running? The ABC inside the S8 is 8 days but it will not do a 200ppm adjustment in one period, it probably need two cycles. But if the S8 has been running for 3 weeks or more I'd say that the S8 is the correct one.


PS. I work at Senseair (2 days a week) and if you PM me the serial number of the S8 I could see what calibration had been done at factory. If the sensor is miss-behaving I could hook you up with a test sensor for further reference.

[halli]

Thx，my s8 just run about one week，so，I will continue monitoring it for a while.
but i am sure that s8 is not correct,because I put it in Outdoor environment for a while ,it's Minimum readings is 460PPM,I think it should be about 400ppm

[grovkillen]

Then I'd suspect there ABC will take care of the S8. But if the S8 is reporting 460 ppm for the outdoors I would suspect the MH-Z19 be incorrect also? I.e. measuring too low?

[rickitaly]

Hello, i just purchased a Senseair S8 and connected to Wemos D1 mini to give me CO2 data with ESPEasy.
First of all i put it outside to check proper values, and here is what i get:

co2.PNG (29.41 KiB) Viewed 5480 times

How can it be correct? Never less than 500!
Please do not consider the spike, i rebooted and tried to change the Wemos to another one.
Thanks!

[grovkillen]

Did you buy it from me?

[TD-er]

Did you buy it from me?

Made a typo in your (re)calibration lab?

[grovkillen]

I hope not!