Originally Posted by bcr229

Sandwich the thermostat probe between the heat pad and the underside of the tub.

Do not worry about the tub being warped because the heat pad should be stuck to the underside of the tub.

Use a heat gun to measure the temperature of the tub floor over top of the heat pad; that is what should read about 90*F. If you use a thermometer with a probe it will read low because very little of the probe is in contact with the floor; you're really reading the air temp over the heat pad.

If you put a hide over the heat pad that will help trap the heat underneath of it.

Oh and congrats on getting your new baby's home prepared and running properly before it arrives; most people don't do that.