8” masonry rocket build and 6” rocket in one barrel

Hi folks,
Joseph Crawley (Asheville NC) and his friend Caleb, a mason, joined me for a team effort to help a gentleman in North Carolina this week build both an 8” masonry rocket mass heater with blind benches and a 6” rocket heater self contained in one barrel (plus a 11” pedestal/manifold.) We started Monday morning and had the first fires in both units tonight.

Here’s the 8” masonry build.

And here’s the 6” rocket self contained in one 55 gallon barrel I just completed for him. It uses Peter’s new double shoebox (top port) design, a firebox door designed for Ugly Drum Smokers, a USSC 6” flue collar, and a clean out T in the 6” flue to use to warm up the chimney and prevent smoke back by inserting a small fire starter (or in this case we just used heavy brown paper from the refractory mortar bags.)

The firebox of both these stoves utilize a shippable core with 2600• HS (High Strenth) large insulating fire bricks for the walls and 1” ceramic fiber board for the roof. The 8” system is a tradional left sidewinder with 60” vertical riser made of 2300• regular insulating firebrick. The shoebox on top of the 6” firebox utilizes 2” ceramic fiber board for the walls and 1” for the top.

The barrel got to 800 degrees tonight but I still need to drill some air inlets in the firebox door frame.

Our drawings for the 8” masonry rocket mass heater were pretty basic old school pencil on graph paper drawings which, with apologies, are a little the worse for the wear after this build.

Here’s the 3/4” air inlets in the firebox door frame.

The homeowner was heating a HUGE interior space because the house was literally built like a modern barn, and only a third of it was finished and insulated, the third where we built this massive masonry rocket stove. So while this masonry rocket heater was performing exceptionally well, all the heat was flowing out into the main part of the structure and straight up the large third floor cupola, and he was having trouble keeping the temp up in the finished/insulated part of the structure.

Since I left, I recommended he build a wall with French doors at the end of the finished/insulated space to separate it from the rest of the structure and keep the heat in the finished area from the masonry rocket heater. He has almost completed the wall, and is thrilled with the results, as the first floor is staying really toasty, and the heat from the masonry rocket rises up the stairwell in the finished area and is keeping the second floor of the finished area really warm as well.

The homeowner sent me a text today:

“On another note - the statistics of this bell heater are going to knock some socks off. I only have to burn maybe 1 full load in a day, maybe 2 arm loads, keeps the whole place toasty - wonder what insulation can do? haha.”

There must be 4000-5000lbs of mass in the masonry of this stove, and that’s the key distinction when people who have them claim they only use a fraction of the Firewood they would have burned in a regular wood stove. They capture, hold then slowly release massive numbers of BTUs. I don’t even think my Woodstock soapstone Ideal Steel Stove (an incredibly clean burning hybrid modern wood stove) could have compared to the effect this mass has on gleaning every ounce of heat out of the exhaust stream.