Help - Add thermal mass to this strange wood stove

I just spent $100 and bought a 1,200 lb "pipeline" stove. I have attached a rough sketch of it.

It is 1/2 inch steel and has a core cylinder about 31 inches long and about 31 inches in diameter. It has a door welded on 1 end and it has a flu pipe for smoke out the other end of the cylinder.

The cylinder sits within a 1/2 inch steel box. The steel box does not contain the fire. It only holds the cylinder and holds the heated air. There is a hole about the diameter of a 5 gallon bucket on the top of the box that allows heat to come out.

I am thinking of adding volcanic landscaping rock into the steel box (not where the fire is but outside the cylinder inside the steel box). After I surround the fire chamber (cylinder) with that volcanic rock. I would like to add some more thermal mass on top of the stove where the vent is.

Any Suggestions?

Jr. Hebron & 'Permies Cloud' : For the rest of this year I will be asking people to post their locations, look at my name and information and then at yours, while not specific to your
question often knowing location will help find the right answer ! You can add yours by going to the permies tool box near the right top of the page and click on . . . 'MY PROFLE' .

I have not even heard of this stove, and google was no help ! You did not mention any existing insulation, what is in the cylinder for fire brick or for insulation at all !

I am concerned that you might require the Air space as a radiator, and if you fill that space with insulation you could actually create a much hotter fire that would cook the carbon
right out of the steel. You did not mention other doors, for ash and coals removal or gaskets or any primary/secondary air supply to the furnace, do you have a history that goes
with this thing?

Insulating the fire box, or in this case creating one, will quite sharply reduce the size of the interior of the fire box, which brings me back to why you wanted this monster, what is
your location and how /where do you propose to use it !

The best I could advise you on adding Thermal Mass would be to stack Brick Pavers about 1 foot outside of, and around the outside in a loose lattice or bricklayers running bond,
with almost as much air as brick, this will help in three ways!

It will take up the heat radiated off of the barrel and re-radiate it for longer, at a lower and safer temperature ,deal with dangerous hot spots, and keep things and people safely
back from your exposures !

So my advice until you can share more information, would be to move forward slowly, a few hot spots with areas that glow red when you take pictures with one of these new
fangled Smart Phones- that detect IR heat radiation, or some dark red hot spots that can be seen in a very dark room, may be telling you that you have added too much thermal
mass, especially any added around the hole in the top of your 'pipeline stove '! For the good of the Craft ! Big Al!

Thanks Allen for the input already.

Let me try to clarify a few things.

First, my insurance will accept a stove like this but it will not accept a rocket mass heater which is why I bought this stove.

I am in rural central KY.

A "pipeline" stove is fairly common here - built during the 50s to 70s in someone's garage or shop. It is literally a 1/2 inch steel pipeline with ends welded onto it. This is the type of stove I grew up with. Fill it full of wood and it overheats the entire house. Usually, that is it.

But this particular stove has that pipeline with welded ends surrounded by a 1/2 steel box that is full of air.

There is no insulation (firebricks, etc.) of any kind in this stove. There is no ash trap or separate ash door. To remove ash, a person must wait for the fire to die and then scoop out the ash with an ash shovel.

The stove is going into a 1/2 basement. Total square feet of house and basement = 2200 sq. ft.

The standard around here is to burn a few chords of wood at winter. That is completely ridiculous, but that is how inefficient the homemade stove are and how poorly insulated a lot of the farmhouses are.

I am looking for any suggestions to building thermal mass outside the fire box.

I think the reason for the outer box with the hole was to pipe it into a central force air heat system. You pipe that hole to the cold air return of your HVAC and turn on the fan to circulate heat through the house.

I do think the air was meant to be moved away from the stove, but the man who had it built did not have a central air system.

It was built to put in the garage. The heat was blown to the house on the other side of the wall - literally 3 feet away from the stove.

I am not going to run it through ductwork like a central unit though.

I would prefer to build hot short burn fires with thermal mass as opposed to long, cooler fires all day long.

Jr. Hebron &' the Permies Cloud' : No problems, I promise I was not really trying to "sell you a Rocket Stove'', in fact I spend between 1/5th and a 1/4th of my time trying to talk
people out of building Rocket Stoves who try to use them beyond, or in spite of their real or supposed capabilities ! The volcanic rock that you want to use for I AM assuming
insulation, will have a tendency to trap enough heat to shorten your stoves life, Even just adding Thermal mass should be done slowly for the same reason!

Fans would help ! Good luck !! For the good of the Craft ! Big AL

Big Al, I do appreciate your thoughts. What do you think would be the "safest", most conservative distance from the fire box (cylinder) to preserve the integrity of the steel?

I also have young kids - under 2 years old - who will be in the basement. Any thoughts about how to build a stable thermal mass that could serve as a barrier?

Jr Hebron : Three suggestions ; One, probably the best insulation to promote longevity of your system and safe higher temps is leave a good bed of ashes in your fire box,
-as long as they stay dry ! . . . . Two, go to Harbor Freight or Graingers or Northern Tool and look for a hand held Infrared sensor with a laser pointer , it will give you spot
temps of the steel, (not the temps of the hot gases on the other side though!)!

Three : If you are lucky you can find a local contractor who is doing a teardown on an old cinder block or brick building, and you can go with the almost as much air as brick
masons running bond pattern it will work like the radiator in your car handling higher temps and re-radiateing them safely at a lower temperature !

Once a week I am compelled to have a meeting at 'their' location, I am always early and can spent that time loading up on Low grade iron ore, many of the chunks are a vein
of the ore body trapped between two slabs of native rock, and I hunt for the pieces with two flat sides, 500 # is two more heavy, or three skinny people riding back with me,
as it is mostly down hill I have a small fuel savings over going home empty.

Find a good native rock, slate or shale, out of stream beds will work- if not stacked too close to the fire, Watch for the red spots, dry stack carefully and use the IR gun often,
Without seeing your monster that is about as close as I can come ! G'luck, For the Good of the Crafts ! I am sure others will have more ideas !

Think like fire, Flow like a gas, Don't be the marshmallow ! As always, your questions and comments are solicited and Welcome ! PYRO - Logically Big AL !

You should be able to pile rock and urbanite OUTSIDE the box, like the pocket rocket in the wofati or weekly picture thread. The airspace should keep the steel safe and the heat should still be in the room. Heating the air is not the most efficient, though.

If you can find one of these cheap: http://store.colemans.com/cart/us-gi-thermoelectric-fan-p-2315.html?currency=USD

It looks like it would be perfect to put in the hole and let it push the air DOWN for no power. But not at that price

I seem to be agreeing with Rscott quite a bit here lately... don't discount the idea of using this as a wood furnace. They may be inefficient as far as fuel consumption is concerned, but they are fantastic for heating your house... Kinda like a prius is really great to go get groceries in, but won't haul your tractor worth a flip.

If this critter is really made with 1/2 inch steel, and is that large, I can't imagine needing any more thermal mass, it's gotta be ridiculously heavy! Thermal mass isn't really suited to hot quick fires as it takes a while to heat up.

The wood furnaces that I build are similar in size, I can get 18 hours of really good heat out of them and still start a fire many days later with the coals that are left over, you can rig a fan/blower with a thermostat and control the heat in your home while using wood instead of gas or electricity (at least not much)... I know you said that you don't want to tie it in to your ducting, but I'm only suggesting that you give that a little more consideration as it is really a wonderful way to heat your home.

If you can heat your entire home and only stoke the fire twice a day max, that's not a bad option.

M Foti I am encouraged to hear you have such long burn times.

I do hope this will be enough thermal mass added that I do not have to mess with the stove every few hours.

I appreciate your comments and suggestions. They have been really helpful.