The Liberator Rocket Heater

For some time now, have been looking for a rocket mass heater solution to replace an existing pre-fab metal fireplace,that is a vanity appliance, that as near as I can tell, is only designed to burn massive amounts of firewood just to provide the ambiance of a wood burning fireplace.  But sends most all the heat up the chimney. The two leading replacement candidates are a masonry heater, and now giving thought to a Liberator rocket heater.

On the latter, have downloaded the owner's manual, and studied countless youtube videos, and aside from Uncle Mud, have concluded most of those who have created Liberator content on youtube understand very little about what they have. With exception of Uncle Mud, most are treating it as a simple wood stove. They have it piped straight to a chimney, so most of the heat they generate still goes up to the chimney, then to deal with all  the excess radiant heat they users are choking them down to slow them down. Not how they are supposed to work. All of these need some sort of mass downstream of  the heater. Either a bench or a bell.  The fireplace space I have to work with is 6' wide, 7' tall and 2 1/2' deep. Inside that area, I'd be building some sort of bell.  Operation would be to open the stove up, let it run hot until the heated area is warm, the bells are warm (and radiating), then shut the heater down. There is no reason to keep one of these running 24/7. It is not a low output wood stove.

A second issue I see with most is if these are being operated inside a modern, what should be air tight home, free of drafts........these will all need a source of outside makeup air. Few, if any have that.......so they don't draw well.......or worse, backdraft. The Gen 2 stove manual actually calls those two round ports "air intake ports" and give instructions on how to connect one (you only use one)  to outside air. Even if an attempt is made to vent them to a source of outside air, it is remarkable how poorly this is understood. I checked and my existing fireplace does have an vent to supply outside air. It is a plastic, louvered type typically used as a dryer vent to exhaust warm, moist air from a clothes dryer. A one way vent....flow runs from inside to outside.  If you try to draw intake air thru it, the louvers would suck down tight.

So for those that know, a few questions. First, I do not see the point of buying wood pellets. If doing that, why not buy gas or electric? Or only use the heater as emergency backup heat for when the power goes off. But as for the pellet heater option, would wood chunks (golf ball to baseball sized) work with the pellet burn basket? Or without?

From what I can tell, the burn chamber is simply the thick walled square steel tube. No fire brick? If no fire brick, is there any sort of erosion of the metal from the heat? The first Gen stoves show air fin radiators on sides and top to disperse the heat. Gen 2 does not. Are those not needed? Almost all wood stoves I've seen still line the stove with loose stack firebrick for hot coals to rest on. I would think this would work the same way?

Any other comments? Observations?

OK, did a bit closer look at one of Uncle Mud's videos, and it does appear the ceramic heat shield does extend into the burn chamber. So got that covered.

This is a hasty, poorly drawn sketch of what I think this might look like. I would have combustibles on both sides of the brick enclosure, so not knowing how hot a bell would get, figured a guy could put in a space between bell and outside wall as a thermal break. Once into the build, if there was room, you could put top and bottom vents in the thermal break area such that it would be allowed to draw, further cooling outer wall and drawing heat into the room via convection......in addition to radiation. The heater enclosure would be surrounded by a bell.......two legs with a crossover on top. Fire exhaust dumped into one leg......rises....goes up and over heater, then cooler air sinks to bottom of second leg, enters chimney pipe, then goes up and out the roof. There is existing stovepipe for the fireplace, and it all runs inside and interior chase. So the whole thing should draw pretty well once it gets going.

to moderators........can you move this thread to the RMH thread? Wood burning stoves is not the right place for it. Thanks1!!!

Hello Eugene!


The liberator is a great design.     It is probably what I will ask Uncle Mud to install in my house next year.   I am kind-of stalling, hoping he creates the 8 inch model.  


Outside air intake:  
This is on the liberator so they can get the UL listing.  In some areas, if you are installing the liberator to meet code they may require you to hook this up.   If you don't have to meet code, you don't have to set this up.  The stove will run well and draft either way.  Most homes have plenty of cracks and gaps to let the stove draft.  You will be creating so much heat with your rocket heater that a little fresh air will be nice.


Wood pellets:  
The liberator has a pellet hopper and will burn pellets as a convenience.  For some folks that is easier.
You can burn wood chunks or sticks, shop scraps, whatever wood you have.     I think I would get the hopper with the liberator even if I was not planning to burn pellets.  Just as a backup or to experiment with.