Rocket Stove/Mass Heater

[Gobblerforge]

Some months ago I started work on an innovative heating system in the garage. I took out my trusty wood stove and built what is called a rocket stove with a thermal mass heater. Wood is the fuel but this stove will give much cleaner exhaust. It doesn't smolder like a conventional wood stove but instead draws hard and hot and releases the BTUs quickly. The very hot air now instead of going up the chimney will instead be flowing through some 20+ feet of 6" pipe that is encased in a couple of tons of cob, brick and stone. No creosote in the chimney and only CO2 and water vapor out the end when up to running temperature. The averages seem to be about one hour burn to ten hours of heat release. I average about 3 to 4 cords a year to maintain 50*+ in the garage/shop. If my hopes are realized I expect this winter to be half or less wood used. If so then this system will be built in the house next summer. I took a lot of pictures so I will be posting for a while. I started by making a brick wall around it instead of cob only. I had a friend give them to me so the price was right. I never did a brick project like this so my lack of skills were apparent right off. That didn't matter because the spirit of the project is hand built without complicated tools, levels and the like. Built by eye and hand. I cut a hole in the wall between the wood shop and metal shop so that when finished, there will be a heater, the end of the build, exposed to the metal shop. There are hours and hours of videos on Utube and websites that can explain details better than me. Erica and Ernie Wisner and Paul Weaten have many videos and are wonderful resources and are explained in laymen's terms and I thank them.
Gobbler

[Gobblerforge]

Cob stompers,

[Gobblerforge]

Cob

Ash trap and entrance to the exhaust.

J tube fire chamber started.

[Gobblerforge]

The heat drum.

Getting there.

[Gobblerforge]

The main work is done.

The temps of the mass is pretty uniform from end to end cold at 73*. Break time.

The material left will be used for slip glazing the surface of the cob.

[Malamute]

Good post, thanks! I've seen some info about this, I'm curious how it works out for you.

[Blaine]

That sort of heating makes all the sense in the world. The Koreans called it "ondal", and often the fire pot was where they cooked meals in the older homes. I've seen a few Swedish Tile Stoves that take the concept vertically up the wall. As you say, very little smoke escapes because it's a hard fast burn, and the mass keeps and radiates the heat.....

[Gobblerforge]

Good post, thanks! I've seen some info about this, I'm curious how it works out for you.

Meee too. I'm still waiting for the drum lid to show up.

[Mainehunter]

Nice Job! I know someone who built one a few years ago and BOY, it puts out some HEAT!!! The key thing is to keep the heater going to prevent the mass from getting too cold.

Mainehunter

[plowboy 45]

Nice lookin project

[Gobblerforge]

Bringing an update. The heater is pretty much done and is working great. I'll get more data when the temp drops and I can burn for effect. For now here is a video from a month ago or so. hope this works.
Gobbler

[Gobblerforge]

First spring report on the Rocket Mass Heater after 6 months. Thumbs up across the the board and almost all my concerns were unfounded. This thing is a masterpiece of economy of firewood and comfort long term. I had no problem maintaining 50 degrees or more over most of the winter in my 1700 square foot shop. I didn't use the metal shop heater any more and maybe less than when I used the wood stove each winter for the last decade. This first picture is the wood pile behind the shop. It was 6 feet high and 40 feet long and I started heating off this pile early October. The square footage equates to 2.5 cords and I fed off the pile down 3 feet to make measuring easier and as you can see, it is down almost to the 1.25 cord level. This is no bull, math on my side, proof of this heater. Last year I burned over 4 cords in the wood stove in that same spot.

The next picture is the over all of the heater. Though it does go from wall to wall it doesn't use any more space than the wood stove and wood pile used to. The wood box on the right is about 4.5x5 feet and is split so I could measure each load. I burn one side and when it's empty I load it and burn the other side that is warm and room acclimated. To burn for 6 hours under normal winter days one side would last 12 to 14 days. Yes you read that right, for moderate temps that's better than 2/3 of a month's heat in that box.

This next is the winter Man Cave spot. the dogs and I take our breaks and lunch here. The spot where Scooter and Frankie are sitting is the warmest floor in the 80's and 90's. The radio up top plays both shops. The wood in the heater is one 5 inch locust log split in 4 pieces and will burn for 2 hours which is about max.

This last one is in the other shop under a bench where the end of the heater comes flush with the wall. I dressed it up like a fireplace and the dogs bed fits perfect. This brick face is 70 + regardless of outdoor temps. This is Gizmo's favorite spot.

My recommendation for any one interested in using less wood and staying warmer is to learn about this design. I can tell you this, there will be one of these in my home next winter.
Staying warm on the ridge,
Gobbler.

[2571]

Y'all should make some wine. You look like Italian peasants crushing grapes.

Neat pic of white dog. It has already staked out a warm spot for sleeping!

[gamekeeper]

Wow! Unbelievable improvement over the old stove. Well worth considering on any new build projects....

[Bill in Oregon]

Really wonderful job. Glad it is working so well.