Uncle Mud Rocket Mass Heater for TinyHouse or Trailer Home 

Thank you for the compliment. I have redone this setup several times, including half a dozen different heaters and three different mass configurations. This one is a solid favorite so far.

@@UncleMud Thank you for sharing!

You got it. Thanks for watching.

Yeah me too. It keeps the raised wood floor from collapsing or catching on fire.

Hello dear sister in law in law. We miss you too. Thank you for watching

It is the coziest place in the house.

We are very pleased how this works for houses with wood floors to get a Maas bench that won't crush the floor or catch it on fire.

@UncleMud Would do that same exact copy of yours! So freaking awesome! Even one section of mass is cool for a small RV as well, great set up.

That would be the Gamera Rocket Heater from Bulgaria. rocketheatergamera.wordpress.com/ tell them Uncle Mud sent you.

Thank you for watching.

Thank you for watching.

We are very happy with them. We are in Montana teaching a Rocket Heater build right now.

I guess im asking the wrong place but does anyone know a way to get back into an Instagram account..? I somehow lost the login password. I would appreciate any help you can give me.

@Conor Leroy Instablaster ;)

@Braden Roy i really appreciate your reply. I got to the site thru google and I'm trying it out atm. Seems to take a while so I will get back to you later with my results.

@Braden Roy It did the trick and I finally got access to my account again. I'm so happy! Thanks so much, you saved my ass :D

Jay, we have used the barrels filled with cob to maximize airflow between the wooden floor and the mass bench because even with mineral wool and lite straw insulation between the bench and the floor we have seen the heat buildup between the bench and the floor (not our build but another experienced builder) catch the underside of the floor on fire. The sensors we've installed are so far showing a maximum temperature on top of the hearth pad directly under the heater of 127 F and a maximum temperature on the wood floor under the bench of 99 F. I don't doubt that someone can build something like you describe and it will never have a problem but I derive a great deal of peace of mind from being able to personally touch and fully monitor every flammable surface anywhere near my rockets.

thank you for watching. it is doing really well for us

Come play in the mud with us some time.

@@UncleMud have you made any design updates since then? Been researching a bit and masonry rocket heaters seems like it may be worth attention too. Curious what your current thoughts are

The current system keeps the floor cool very nicely. Foil is definitely an option. It works better with some space behind it for airflow but it definitely helps keep things cooler. Thank you.

@@UncleMud your barrel concept is really interesting. Here is what I'd suggest, based on baseboard heaters & hot water heating. The shroud around the finned tube is set up to draw cold in and circulate it through the fins and out the other opening. The again in automotive, primarily the catalytic converters, they had a heat shield shroud around their body to keep the floor boards of the car from getting super hot and melting the plastic carpeting in the passenger compartment. Hence, you'd have to fashion sections of sheet metal fabricated as a shroud around the barrels but to exploit the same aspect of circulation as a baseboard . Leaving the space between the shroud and barrels open, would be basic......and probably easier to plan for before laying everything out to fill with the cob.....as opposed to retrofitting. But I would think also the in the space between the shroud and barrel might have some means of fins attached to the barrel as a heat sink to improve efficiency and heat transfer in the aspect of the convection. If not fins, which might be considered in aluminum or copper.......the barrel itself would be nice if it was uniformly ribbed ......its all about surface area and transfer

another option that would be more complexed but maybe more efficient, would be to use automotive exhaust pipe bent to follow the barrel curvature and surround the barrel with these bent pipes. have them all touching and perhaps spot welded together to the barrel and to each other.....as not just the hollow tubes would be the air exchanger.....but having the tubes touching would create other tube passages between the tubes and barrel as a result.......so the whole assembly would be like a honeycomb surround around the barrel. BUT I really like the concept of the raised thermal mass. As I study these types of heaters, having the thermal mass directly on a concrete floor might be too much of a thermal draw if its a concrete slab on top of the ground and not situated below the local frost line for the region.....as opposed to a basement foundation dug out and well below the frost line.

@@mikecamps7226 thank you Mike. This heater is over a crawl space with the usual minimal insulation of a doublewide so it is doubly essential to make sure the floor doesn't get too hot and start the underside of the subfloor on fire--we've seen it happen on other folks' designs. Regarding your previous comment even with all day firing below zero I haven't gotten the floor under the bench above about 104 degrees. I have not been attempting to draw more heat off the bench more quickly for a few reasons, first because I'm not experiencing any overheating. Second because this being a doublewide with a crawl space it is a bigger design challenge to retain heat as far into the night as I can given a relatively small mass for the purpose of not collapsing the floor. Third, we have seen circumstances where allowing the heat to be drawn off of the mass too quickly significantly slows down the draft and messes with the chimney draw and rocket performance. Thank you for the ideas though, we have associates who have built heaters in basements in we areas in direct thermal contact with the floor only to see all of the heat absorbed into the floor. I don't often run across a mass battery bench situation where I feel an urgent need to get heat out of the mass faster, but it is always helpful to have a better idea in my back pocket for when I see it. Thank you again for watching. I would love to see and share your work too if you want to drop a link.

I have seen this work great over concrete floors but I have also seen the foil trick cause problems when it couldn't block enough heat over a wooden floor and the underside of the subfloor caught on fire. Thank you for watching.

Thanks!

We're very happy with it.

Thanks for the feedback

Thank you. Stay tuned for more.

The refractory liner is quite durable on this heater. Thank you for watching.

Kev, Thank you for watching. Generally speaking a rocket heater has a super hot insulated bit for turning wood into hot clean gas and a super massive bit for capturing the heat from that gas and storing it and slowly releasing it. Unfortunately hempcrete will not withstand the temperatures to be a good rocket heater core and is not dense enough to be a good storage mass. Cob works pretty well for both of these especially with help at key points (dense firebrick to protect the burn chamber from physical damage from the firewood and ceramic wool to insulate the riser for best performance).

We will be teaching rocket mass heaters and cob at the Mother Earth News Fair in Belton Tx Feb 19-20 2022 if you want to join us.

@@UncleMud I would love to! Very small chance I can atm. Thank you for the offer. I'm really good with my hands if I can get the physics? I have a few questions if you have the time? Or if you have a book to sell?

@@l0I0I0I0 drop me a line info@unclemud.com

@@l0I0I0I0 I can help you with the physics and give you a peek at the book I'm working on if you drop me an email info@unclemud.com

The Liberator has a place for an external air intake. The Gamera doesn't. It would help a lot. Thanks for watching.

Hello. Thank you for sharing your idea. The floor is wood with wood joists so there will be no rocket recessed in this floor. The climate I live in rewuires a lot more insulation than the metal and brick skin you are describing. Drawing warm air out in the summer would work best if the chimney was removed inside at the ceiling to let the hottest air rise up and out, not the cooler air near the floor.

Umm no just no 😂

Rust

👎🏼

Thank you for watching. I am explaining what I did but I value feedback because I can always learn a better way to do a thing or a better way to explain what I am doing. The piping in the bench is there so it can warm the cob mass in the bench without catching the wood floor joists on fire. If you had an earthen floor with no wood supports under it you could put the pipes under the floor . My experience is that pipes under the floor feel nice and it leaves you more space and flexibility in your floorplan but it does not put as much heat in the building and it is too easy to take too much heat out of the exhaust which stalls the draft in the final chimney and causes the rocket heater to smoke into the room.

We are working with Gamera to add a cold air intake to the next generation of heaters. The current rose winddow design is hard to fit an outdoor cold air intake to. Thank you for watching.

The half barrels are filled with cob around the 6" exhaust that goes to the vertical chimney. The cob stores the heat and slowly radiates it over night so you only burn fuel hot and clean part of the day instead of damping down a wood stove to run dirty and inefficiently all night. The vertical barrel is the Bulgarian Gamera Rocket Heater I am testing. I have several other videos of it on my channel. It is hollow and provides quick radiation to warm the room while the fire is going. The air intake is the little rose shaped window on the front of the feed tube above the glass window. Thank you for watching.

coil the copper around the outside of the barrel so it is in a vertical orientation and can thermosiphon and so it won't be as likely to turn to steam in pockets inside the pipe. Thank you for watching.

Also it will be lovely if you join us. We have all sorts of fun planned. Buy your ticket soon for the best price. I get a kickback if you use my link to buy wheaton-labs.com/permaculture-tech/?f=51

I have had good luck placing a water tank (with a pressure relief valve) directly on top of the rocket barrel raised up off the barrel a few inches so there are no super hot spots. The idea is to keep the tank no hotter than about 160 degrees so it never steams inside and run it out through a thermostatic mixing valve so the water getting to the shower or kitchen sink is never hotter than say 110.

Gamera.eu from Bulgaria three sizes. This is the medium one. Get the big one. All fantastic with a thermal storage mass. Tell them Uncle Mud sent you.

I could do that but it never gets over 104 degrees anywhere under there.

Yes but do it when the bench is warm and do it a little at a time so it can soak in and not just run all over the surface.

It helps in some circumstances, but it isn't essential. Thank you for watching.

as long as you are running a rocket heater (no smoke or soot or creosote) a heat exchanger and mass make a huge difference in comfort and fuel useage. With a normal woodstove the exhaust needs to go straight out at a higher temperature to limit creosote buildup so you don't die. Just stay alert and inspect regularly and let us know how it goes. Thank you for watching.

@@UncleMud Yeah, it's definitely an experiment. I'm going to build in an inspection door so I can check on it. I'm hoping I can get by with it if I burn dry wood but I'll just have to try it. My stove pipe is very short so maybe that will help. Do you have any issues with the mass getting too hot before the house gets warm? For example, bitterly cold days. I'm just wondering if I can run a rocket heater continuously if I needed to? I really want to build one this summer.

Hello, It is a Ford vs Chevy sort of thing. I own and like them both for different reasons. The Liberator is a lot less expensive, made in the USA, UL listed for easy code approved install as a woodstove, has an outdoor air feed and a really great non electric pellet feeder. I built my own glass door for the clean out so I could watch the fire but the gen 2 Liberator will include one as well as a ceramic inside coating. There is also a baby liberator for tiny houses but it is not UL listed. The Gamera is a lot more expensive including air freight from Bulgaria. It is good for a tiny house or anywhere you dont need a permit to install it because it has not yet been UL listed or EPA 2020 emissions tested (it has easily passed the EU versions of those tests), it has a ceramic liner and a glass clean out door for watching the fire and options for extended cooktop and water heating and comes in 3 sizes. Either of them works even better with a thermal mass bench.

If you build the mass bench in such a way that there is plenty of air circulation and not too much weight for the floor it can be built on the main level over a wooden floor like this one is. We have also built bigger better rocket heaters in the basement because they do such a nice job of heating the floor from below and making the basement more fun to be in. If you don't usually go down there it would be a hassle to go up and down stairs feeding your rocket every 20 minutes but if the basement becomes your new hangout space that is a bonus.

What county are you in? I’m in Coshocton, gonna build one this summer if you want to help/learn from my mistakes

Yes but it easy for a cold floor to take too much heat out of the exhaust so the chimney stops works--chimneys need at least 170 degrees (F) to create draft. Been there done that got the non-working rocket heater I had to rebuild. It ended up working when I reduced the pipe in the floor from 20 feet to about 6 feet. In a well insulated mass floor it would work better.

@@UncleMud Thank you for the reply my friend. I hope you don’t mind but I have another question? After the gases travel under the well insulated voids in the floor does the cooling fumes have to go up a flue? Can’t it just exhaust out at the back of my workshop at ground level? There would be a flue at the stove for starting purposes then once it was running clean divert it under the floor.

Gary, It has been done. Many of the earliest rocket mass heaters were built with no budget for a chimney. It works mostly, but without the strong draft of a good chimney you can get the rocket heater flow reversing if the wind outside changes direction, filling the house with smoke. Mostly working is not good enough when it comes to smoke and fire. I have had good results making greenhouse heaters that bring the exhaust pipe back up out of the floor and right up against or back through the barrel to give the chimney a little bit of heat for sure so it will pull. Another thing about the floor is the insulation would go under the floor so the heat from the pipes in the floor stays in the mass of the floor and radiates into the room, not the ground.

@@UncleMud you can always use an exhaust fan

@@UncleMud I poured concrete under one end of my kitchen and place a small wood stove on it and then ran the exhaust pipe down to lay on the concrete floor back and forth and then finally up to chimney so I had about 20 ft of pipe and I took bricks mostly fire bricks and put against the wall and put in between each pipe and wrapped bricks around the wood stove and then at the top near the ceiling I put an in line fan which I only activated to make a draft in the beginning the system then in the morning it was nice and warm still. Once a year I pulled the end caps or the elbows for cleaning, on the inside of the wood stove I completely lined with brick on the bottom sides and the top near the exhaust,. When I got up in the mornings it was still nice and toasty in the kitchen where I slept if it got too hot I just opened the door to the rest of the house and then when it got too cold I closed the door to the rest of the house. Usually after running this all day it would heat the whole house up the living room I would open the front door and it would also semi heat the porch from freezing cuz I had plastic on a 27-ft porch like a greenhouse and kept all kinds of plants on there, then in the daytime when the sun was out the porch would hit 90 some degrees I would open the door and it would heat the living room up

rocketheatergamera.wordpress.com/ tell them Uncle Mud sent you.

I look forward to seeing pictures.

Notice this configuration is spread out over the floor, mostly balanced atop one of the four big beams under the trailer, and less than 1000 pounds, which doesn't keep the house super warm over night like a 3-5 ton mass would, but keeps us from freezing. It is still usually around 60 (f) when we wake up.

This one heats the whole building (a 1100 square foot house trailer). A house that is bigger or with more closed off spaces will need multiple heaters. Thanks for watching.

Code requires outside air intakes in most places in the US, but there is still serious debate among rocket heater builders as to whether it install one. Some heaters like the Gamera don't have a spot for a dedicated air intake like the Liberator does, but your point is valid. Some houses are so tightly sealed that they need outdoor air intake just to make up for the air lost to combustion. My inlaws had a house so tightly sealed that the gas dryer and the gas furnace and gas water heater were backdrafting and extinguishing each others' pilot lights when all three tried to run at the same time. Other houses have far too much air leakage already, so one way to think about the question is whether you want your makeup air to come directly to the woodstove or from the cracks around your windows so it will run down your back and make you cold before it feeds the fire. Another way to think about the same question is to ask yourself whether you should get to breathe that fresh air and let the fire breathe your smelly sock air instead of getting its own fresh air intake. A blower door test can help you figure out whether you need makeup air or if you need better weather sealing to save energy. Bringing in your fresh air where and when you need it can make a big difference in comfort and energy bills. A whole house air to air heat exchanger is not cheap but it can sure make your house healthier, safer and cheaper to heat. On some rocket heater installs (like in a basement) the danger of backdrafting into the outside air intake is a very real consideration. In those cases and with heaters like the Gamera I run the air intake hose to a spot near the heater wood feed where there won't be a draft or a backdraft. Thank you for watching.

@@UncleMud thank you for such a well written reply!

Positive heat pressure using air from outside would be the ideal way to boost even this most efficient heater

Thank you for watching

We have an outside air intake.

I painted over the nasty vinyl wall covering with primer mixed with sand to give the cob something to stick to then smeared it on with a trowel. Thank you for watching.

The bench is full of cob (sandy clay soil) and the pipe.

six to eight hours to get toasty

@@UncleMud I think I made mine too large. It’s been 2 weeks and it’s just getting warm

@@joesears584 it should get easier to heat as the cob dries

It would need a lot of preparation but it would work www.sciencedirect.com/science/article/abs/pii/S0378778811002301

@@UncleMud thanks! I’ve also got access to ag lime and limestone. Several local quarries around my area. Thought about using that too. More like a pebble style bench.

more heat goes into the mass battery if the heat tubes are blocked

We developed this type of thermal mass bench because a lot of Tiny Houses and pretty much all trailer houses have wooden floors that can't handle the weight or direct heat exposure of a typical Rocket Mass Heater thermal mass. We have built similar designs in a treehouse, a school bus, single width trailer homes, shed homes and double wide trailers like mine you see here to show that the design is scalable. Thank you for watching.

Me too. I find the cleanout at the base of the vertical chimney is a great priming port. I open up the cover and light a firestarter or piece of waxed cardboard inside to heat the chimney. Wait 4 minutes and the rocket lights right up. Thank you for watching.

The stove was about $2500. The 8 cast iron legs on the bench were from 4 $60 oven kits ar Tractor Supply.

No. I am testing the limits of what this heater will do. The manufacturer's recommendation is a 12 ' bench max with 1.5 times that minimum chimney height. Your results may vary. Thank you for watching.

Branden, Thank you for watching. I have several install and review videos in my youtube channel from my multiple Liberator builds. ru-vid.com

Also the Gamera runs like a champ. I have installed several of those too.

I did find those thanks do you have a local supplier for the gamers stove I really like the look of those

I have several Gamera videos on my feed here. They have to be ordered from Bulgaria via gamera.eu as they are not certified for code install in the US only in the EU. The larger Gamera 7 puts out about twice as much heat as the fantastic Liberator.

Have you did any installs with a vertical mass what are your thoughts on this I'm in Pa and going to be building a home this spring tiny home with a connected greenhouse is our hope

For the heater either the Gamera or Liberator Rocket Heater will run around $3000. The CottageRockets I build out of scrap metal. They generally generally cost $300 to $500 plus a couple days puttering in the shed. The bench cost a couple hundred dollars and a couple days of labor.

Yes, the same as any other woodstove, but rocket heaters are generally continuous feed rather than batch feed. This helps them burn less fuel more efficiently and cleanly, but it also means that they will only run for 20-40 minutes between feedings. The liberator (not this one, this is the Gamera does have a pellet feeder though that I have run for up to 28 hours on a single 40# load with a slow draft.

fire heh heh

Thank you for watching

Yes. It feels really good.

You can order them from Gamera.eu if you really want one to test yourself , but air freight and customs duty are expensive and they are not UL listed or EPA tested for installation in the US. We are working on the testing but it is going very slowly as the EPA offices are very back logged right now.

We have those modern complicated systems but they are so much more expensive to operate and less fun so we build this stuff.

@@UncleMud I quite agree........that's the price you have to pay for living in the 'burbs.

Suit yourself. It saves me thousands of dollars a year compared to propane or even my previous woodstove.

I've built perfectly functional rocket heaters out of junk lying around. If you want someone else to build it for you its going to cost $2k to $3k USD for one of these or more for a ig hand built cob and masonry rocket heater. The US definitely has its share of corruption and common sense crisis but I'm not seeing how that relates to my heater that runs on scrap wood.