Humidity Sensor for an Incubator

Well, I would check that the new ones are the correct type and haven't had a design change that might make them refuse to work with your system...

If a sensor from another unit works sounds like the new sensors are possibly faulty?

John.

Vaisala is a recommended cost effective source for humidity, dew point, wet and dry bulb temperature instrumentation.

What's that got to do with Johnny's problem??

John.

Learn to read Psychrometry Charts to read off humidity%.

Use a Dry bulb and a Wet Bulb Thermometer--and interprete!

Thermometers always work.

Again, as Electroman said: "What's that got to do with Johnny's problem??"

Sorry Electro, I couldn't resist.

Johnny, I assume you are not trying to design a new incubator, and the one you have is automated so swinging two thermometers around probably won't interface well with the control system. I think you might get more help if you explain the make and model of the unit you are working with; another assumption that it is not a one-off device. If you post the manufacturer and model of the machine you might get someone that's worked on them before to help you. I am sorry I don't have any more useful suggestions, but I cannot even go lookup info for the machine you are using; which I might have done just out of curiosity.

Humble Psychrometric solutions for humidity.

http://www.engineeringtoolbox.com/fuels-ignition-temperatures-d_171.html