Why not just turn up the thermostat-----I have never had to keep opening and closing vent holes. The last time I checked my humidity it was in the 50's while incubating and around 70+/- for hatching. I checked the humidity the first time I incubated/hatched with the incubators I have now and I have never checked it again----that was over 1000 chicks ago.
I talked to several on here----not sure how yours is set-up----Are you using a fan? What type thermostat? Is the thermostat close to the heat source?
My incubator recommends 45 to 55% humidity for incubating and 55 to 65% for the final hatching. These numbers have worked for me and I hatch hundreds of babies every year. One thing that has worked for me is keeping a cool mist vaporizer going in the room during incubation and hatching. I live in a very dry climate where the outside humidity is often below 10%. If you live in an area where outside AND inside your house is humid then you may not have as much problem keeping the humidity at proper levels.
