thermostad
thermometer
Yes, you're right that's called thermostad.
Thermostat
A device for regulating furnace heat is the thermostat. A programmable thermostat can be set to control the temperature inside the home on a regular schedule. The thermostat is set to a desired temperature and then the furnace turns on and off to accomplish the desired heat level.
There is always a wall thermostat for regulating furnace heat.
thermostat is commonly used to regulate the heat of a furnace. It can programmed to maintain a desired temperature by turning the furnace on or off as needed. Some thermostats have additional features such WiFi connectivity, smart home integration, and scheduling options.
In a furnace large amount of the heat supplied is wasted in the form of exhaust or flue gases.. that s called as heat loss in a furnace..
air handler
Is the furnace a hydroponic system? If it is you only need to get a heat exchanger (As you don't want the water to your heater flowing through the furnace) and plumb it as another zone in your house. If not you need to find a device for heating water that fits your furnace. and plumb the heat exchanger to that. I believe an heat exchanger is required by code in either case.
A heat pump will do this, a furnace should not. Are you sure you have a furnace?
ruud furnace only blows cold air, no heat
Furnace is an enclosed chamber in which heat is produced