Hello Dyson Community,

I recently added a second Dyson Purifier Humidify + Cool Formaldehyde PH04 to my home, and I've encountered an issue with humidity readings that I hope to get some insight on.

I've been a satisfied user of the PH04 model, with one unit already functioning well in our master bedroom. Encouraged by its performance, we purchased a second PH04 for our living room. However, upon setting up the new unit, I noticed a significant difference in the humidity readings between the two.

The first PH04, located in the master bedroom, shows a humidity level of 43%. Meanwhile, the new unit in the living room reports a humidity of 49%. To cross-check these readings, I used a digital hygrometer, which has consistently shown a maximum deviation of 5% from the first Dyson unit. However, the reading from the new PH04 differs by about 10% from the hygrometer.

Here are my questions and concerns:

1. Is such a variance in humidity readings between two PH04 units normal?
2. Could the discrepancy indicate an issue with the new unit's humidity sensor?
3. Are there any recommended steps I should follow to calibrate or test the accuracy of the new unit?

Any advice or similar experiences shared would be greatly appreciated. I'm keen to understand if this is a common occurrence or if my new unit might require some sort of adjustment or servicing.

Thank you in advance for your help!

Best regards,

Yong-Jin Lee