Boilers can generate heat with either oil, gas, or electricity, which is burned within the boiler to produce hot water or steam. This hot water or steam then circulates through pipes that lead to radiators located throughout the home or building, providing warmth and heated air. Ultimately, the type of boiler you choose will depend on your needs: how much heat you need, the size of your home and property, and what type of fuel sources are available in your area.