Hydronic heating is a newer form of heat that circulates hot water through pipes in the floor, radiating the heat up into the air and the room. Any signs of moisture in the carpet or on the flooring should be immediately checked by a professional in hydronic heating as this can pose a serious structural issue for the home if there is a leak.
When replacing a thermostat it is important to stick with the same type of thermostat. Not all furnaces and heating systems will respond to all types of thermostats. If you aren't sure what type of thermostat you have bring it with you when you are shopping for your new unit.