A rocket stove that heats a cob bench and a central staircase.

This beautifully styled cob bench and rocket stove is by Danish architect Flemming Abrahamsson. The rocket stove is a heat pump that moves hot gas through a heat radiating chamber, the barrel, and then through built-in furniture acting as a thermal battery. A rocket stove can easily push hot gas up to 40 feet (12m) of pipes, storing heat in the interior walls, floor or seating.

The cob bench then slowly releases the heat keeping the room warm while the stove is not burning. Flemming's rocket stove not only heats the cob bench (above) but also, and uniquely, it heats the central cob staircase (left) bringing the heat right in to the heart of the home.

Below is a video presentation of stoves from Ernie & Erica Wisner with the section on rocket stoves from 20 minutes.
 

The Rocket Stove Class

This book by Ianto Evans and Leslie Jackson is without doubt the best guide you can find to building your own rocket mass heater.

The idea of heating a bench or bed is a very old one. In China a heated living space and bed is called a kang (PDF 700Kb) and dates back to 5,000 BC.