To Krodal, Thank you for your response.
Is the display on the remote sensor, or on some kind of central control unit ? - No it does not need to be. The display could be attached via wires to the sensor board and then I could hang it on my wall.
How far is the distance from the remote sensor to the central unit ? - Maybe about 5 to 6 feet.
Is that central unit connected to ethernet, or also wireless with wifi ? I have a wireless router in my house, however I do not have the central unit built. That is what I am looking to acheive here.
Does the remote sensor have ethernet connection ? - No...it would connect directly to the central unit and from there that would transmit wirelessly.
Is it perhaps only the remote sensor without central unit, and have the remote sensor (for example with wifi) run a website on it with the data that you can see on a tablet or smartphone. - If this could be the case, then that would be great.
What kind of display. Is a very cheap LCD of 2x16 characters enough ? - Just enough space to tell me, temperature, pressure, maybe time and a wi fi icon.