If you are looking for something to heat a space like the shop or the GREENHOUSE
I built one of these for the wife's greenhouse. She had stocked it with wood and asked her sister to check it out the next day. It was still burning and putting out tons of heat but sister put in a few more chunks of wood and closed it up as before. Wife went home last nite got up this AM and checked it STILL LOT-O-HEAT
Easy to build and REALLY WORKS GOOD going to build one for my shop and vent it out the side so I can close doors in winter.

