The dimensions and form of a masonry heater are variable,
depending on the area to be heated and the style of masonry
heater to be built.
The most comon heater built today in north America is the Finnish downdraught contra-flow. The dimensions below are for a large Finnish contra-flow heater that would easily heat 2,000 square feet.
Width = 1194 mm
A typical chimney is located on either side or the back of the heater no less than 4 inches (100 mm) from any corner of the heater.