What is a Masonry Heater? A masonry heater allows you to heat your home with wood in a unique way. The main thing that distinguishes a masonry heater is the ability to store a large amount of heat. This means that you can rapidly and cleanly burn a large charge of wood without overheating your house. The heat is stored in the masonry thermal mass, and then slowly radiates into your house for the next 18 to 24 hours.