Do you have vents that warm or cold air blow out of?
This is the most common form of system and is called Forced Air. These move air. On a dry heat system, you will see ductwork.
Do you have a gas or electric stove?
Do you know if you have a heat pump? Not all Compressor (exterior) units are heat pumps.
Do you have radiators or pipes that warm your home?
Wet/Steam units are defined by Boiler System, Baseboard Radiators, Radiators. This is a radiant heat system and uses a boiler. In this system, the heating elements are visible like baseboard radiators, and radiator.
Wet/Radiant System are defined by presence of: Boiler, Expansion Tank, absence of baseboard radiators and radiators, large grouping of valves and pipes near the boiler system. The elements that heat the home are in the walls and the floor.
If you go in the basement, you see a boiler and large pipes. Do you see a large metal vent going in to a chimney or do you see white PVC coming off that boiler? Can be steam or water.
When a boiler system is present, look for the telltalk signs of radiators or missing radiators to define whether the system is a Wet/Steam or Wet/Radiant
Do you have electric baseboards in your rooms as heaters?
Do you see a copper line? This means it is wet-steam heatin unit.
Otherwise, this is Baseboard heating or line voltage heat runs on 120 or 240 volts.
Do you have a floor or wall furnace or decorative heating stove?
Typically, these are gas systems