Uncle Mud's Ultimate Tiny House Rocket Heater Upgrade: The Hot Cob Mullet

Tiny Houses are a special challenge for heating with wood. Generally they aren't very well insulated and a heater big enough to keep you warm through the night will overheat you in no time. There are special challenges with a Rocket Mass Heater. Many Tiny Houses have wood floors and wood walls so its a bit tight fitting a mass heat storage that is big enough but doesn't collapse the floor or catch the walls on fire.

The Red Cabin at Wheaton Labs has been our test bed for Tinyhouse Rocket Mass Heaters for about ten years now. I think we are up to about a dozen different designs now. This one works pretty well, but we are still tweaking it.

The mass bench made from pebbles and cob and dense rock does a great job of storing heat while keeping it away from the walls but we have also discovered that if the room warms up too soon people stop feeding the fire, the mass never gets fully warmed up, and the room is cold by 2am.

So last year we built a sand battery around the burn chamber to slow down the heat. That helped a bit. Over in the Love Shack we found that adding rocks to the top of the radiant barrel--where its the most uselessly hot--does a lot for keeping the heat from just convecting up to the ceiling, but it works best if the barrel top mass is all one piece. The heat lasts longer.

To continue that experiment I am installing a cob surround on the top and back . I call it "The Mullet". Paul hates the name and wants to call it "The Cape and Hat". So I call it "The Mullet."

In case you don't know, a mullet is a particularly American hair style worn short on the top and long in the back--or as they say "Business in Front, Pleasure in back". In this case the Hot Cob Mullet is an add on for the Rocket Mass Heater that traps the heat off the top of the barrel of a Rocket Mass Heater that would have warmed up the room (and stopped people from feeding the fire) before the mass bench is fully heated up. Lets see how it works.

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MULLET IT IS. Splendid.

I'm pretty sure the official US patent on the mullet specifies "Business up front, party in the back"...