Incubating and humidity in covatutto 16l

[Jo-C]

Hi, I'm using a covatutto 16l incubator for my chicken eggs. According to the inbuilt theremometer its keeping at a steady 37.8 As the instructions say. However I filled just one part of the tray with water as instructed. It recommends you fill the water every other day but mine has not disappeared at all. It's still full. I bought a cheap hygrometer yesterday, calibrated it and then put it in with the eggs overnight. This morning it is reading 29-30%. Isn't this too low? Do I fill the other water chamber although the instructions say only fill this on lockdown. It's in my spare room which feels quite cold but the incubator temperature is staying steady. I'm not sure what to do from here, this is only just going into day 3. Any help appreciated?