Some recommendations drawn from the rocket mass heater world: Don't remove heat directly from the combustion process, because that prevents complete combustion. Instead, extract as much energy from the wood as possible by insulating the burn chamber to burn at the highest temperature possible and achieve complete combustion, and permitting a high airflow to provide adequate oxygen, then collect the heat from the completely-combusted exhaust (not from the burn chamber). In other words, collect the heat AFTER combustion completes.
This reminds me of something a Swedish friend does. He's an engineer, and he built a sizable workshop about 30 yards from his house. The workshop's heated with an odd wood burner he built from a 4' long piece of 20" (ish) diameter thick walled tube. It's horizontal on a stand that puts the bottom of it's door at about 2' off the ground. The door is a plate that sealed against the entire front of the tube without any "Door frame" to get in the way of loading and raking ash out. The reason it was made so long was apparently so he didn't have to waste as much time chain sawing wood into little foot long chunks to go in. He just rams a suitably chunky log in there, builds a fire around one end, and it'll burn for hours. There's lots of adjustable vents on it so he can control the fire at various areas of the burn chamber..... It's a pretty well thought out piece of heavy engineering. Anyway, when he built it, he sliced about a 10" wide strip out of the length of tube, and welded in a thick flat steel "Cooking surface" along the top, and in winter he has 3 seriously chunky lumps of stainless steel sat on there. These things must be a foot long and 18" in diameter (And probably worth a damn fortune now !). Each one has an eye bolt in it, and at the end of the day he uses his engine hoist to pick them up and place them on a trolley. Then he drags that over to his house and plonks the trolley in the corner of his bedroom (His house is a REALLY picturesque old timber frame bungalow on the edge of a forest......... With a ruddy great modern steel framed workshop plonked right beside it. :D). He says that over the following few hours, these stainless lumps bring the temperature in his bedroom a very noticeable amount, and for 2 or 3 months of the year it means the difference between having to turn on his homes heating when he finishes work, or not.
Wow that sounds incredible, I do love the way people can get around a problem & think outside the box & come up with something amazing! Im a big fan over engineering!!
@@leejones2511 I'd guess the "Super heating" when the roll of mesh is in there is probably down to it creating turbulence in the chimneys flow. When you have a gas moving at speed through an open straight pipe you usually get a thin boundary layer of turbulent gas along the walls. This layer actually helps the rest of the gas experience less resistance as it shoots along the centre. In essence, the gas rushing up the centre isn't actually touching the wall, so it's not transferring it's heat into the wall or thermal mass. With the mesh in place, you're causing the centre gas flow to get bounced all over the place. It's going to be getting tumbled into the wall multiple times on it's way out, and each time it does it will be handing over a little more of it's heat energy. I'm thinking that with a couple lengths of all thread, some nuts, and large washers, you could build a basic "Baffle" to hang down into that chimney with washers stepped at maybe 4" spacing on the two rods to buffet the flow one way then the other. It might be a more controllable way to make the airflow tumble. This idea would also be adjustable too, so if one area if the chimney is getting too much of the heat, you just space the washers and nuts out more in that area and bunch them up where the stack's cooler. If you weld the threaded bars to a piece of rebar that can rest across the top of the chimney, it would be a quick job to take them back out and give the chimney a sweep before taking the "thermal battery" into the house. The smoke and smell. I'd put money on it being the paint around the top surface of the gas cylinder getting toasted. I've used all sorts of high temperature spray paints over the years, and have found few that'll stay put on stuff when fires involved. One future suggestion though, if you make a MK2 of this, for rust protection, I might be worth "Seasoning" it with veg oil (like you would a cast iron skillet). It works pretty well on steel, and it gives a rustproof finish that doesn't burn off until some ridicules temperature. It's cheap as hell to do, and until it fully polymerizes onto the surface....... It smells vaguely like chips cooking ! :D
Also had the idea of a rain cap style cover. It will spread the heat more evenly and lower into the room. While the heat is still excessive/high a removable pot/kettle stand could be used to heat, cook or boil water. Nice job!
Well done with this project. It's very impressive. Others have come up with possible improvements, but you have actually created something that works very well. Taking action is the most important thing. I would be proud to have built something like this. The only thing I would do differently is put the fan at the top, so that the hot air warms the bottom of the room before rising to the ceiling.
Yes you are both right the heat for the first two hours is VERY hot & could melt the fan however after that I like the idea of it bowing down as it will mix the air with the rising heat nicely 👍
You could still put the fan at the bottom and blow down to suck the heat out toward the floor. Maybe even just a ring of fans blowing from the bottom in all directions. Until you get the timing down on releasing just the right amount of heat and insolating/storing the extra heat you shouldn't need a fan until half way into the heat release cycle.
Awesome idea. I was going to build a 55G drum put a fire under it. Then set baskets of round stone inside. Lift out baskets and set them around the house. Very similar to the the way natives heat their shelters. Thank you very much for sharing your experience. God bless.
Fantastic work. Surely with an umbrella defuser attached to the funnel it would make the greatest/most efficient patio heater ever. After I saw the Polar Night Energy project I've been wondering if it could be scaled down for domestic use. Looks like you are well on the way. Look forward to phase 2.
I have a wood burning stove in my basement and the exhaust pipe runs through 4 rooms upstairs. Each room has a 50 gallon steel drum filled with sand that wraps around the pipe. Its been heating my 6,000 square foot house for years. It distributes the heat evenly and stays hot for about 7 hours after the fire goes out. If you do it right, a sand battery is awesome when it comes to efficiency. The exhaust pipe is double walled but single walled inside the sand battery. After running for 2 hours the sand batteries have reached max temp. I heat my entire house with only 4 logs a day.
@@guyvenner I don't have any photos but all you need is steel drums and stove pipe with connectors and heavy duty brackets to hold up the sand batteries. I'll explain how i assembled it all.
What I made: I bought a large soapstone stove from a place called Hearthstone. I bought double walled pipe and single walled pipe. I bought steel 50 gallon drums and cut a hole in the top and bottom to insert the single walled pipe. Single wall pipe easily transfers heat into the sand drum. I welded some rebar U shaped brackets on the drums and hung them from the wall and ceiling about 5 feet off the ground. I used fire block panels behind the sand drums because they get hot. I then lined up the holes in the floor and ceiling to run out the double walled pipes. I welded a 1 to 4 way junction right above the stove in the basement but had to add dampers in each pipe because heat was not being distributed evenly. I used a funnel and filled the steel drums with the finest sand i could find.
What a brilliant room heater! Some thoughts: 1. The 'TnT' fellow you talked about in the first video is Robert Murray-Smith. (ru-vid.com/show-UC4AkVj-qnJxNtKuz3rkq16A) Yeah, he is a *FANTASTIC* resource for this kind of stuff and a *BLODDY* amazing guy all-round. *DEFINITELY* check out his rocket stove video for pointers on improving your setup. 2. It *CANNOT* be stated too many times that any time you are cutting a container that was used to hold something flammable, you *MUST* fill it with water, first. Far too many eulogies have been read for people who didn't consider that safety tip worth following. :sigh: 3. Likewise, heating up galvanized metals--like chicken wire--past 200C creates highly toxic gases. *DON'T* *DO* *IT!!!* 4. I would drill a *LOT* of holes around the bottom of the main burn chamber and leave a gap between it and the battery, as the air intake area should exceed the chimney's cross-sectional area for maximum oxygen flow and hottest burn. The more air, the better. 5. The more metal you can put in the air stream *AND* the sand, the more quickly heat can be effectively transferred from the former to the latter--and vice-versa, once it is in the shop/house. Personally, I would have cut the tube lengthwise into sections and then added angled vanes on the inside and multiple straight ones on the outside that almost touch the outer shell before welding it all back together and using it. This would A) create a vortex to push the hotter air to the outside of the tube and lengthening the air path to allow more time for heat to transfer, B) *DRASTICALLY* increase heat-absorbing/emitting surface area, C) as the vanes heat up enough, they will help auto-ignite any volatiles, and D) the vanes in the sand will help transfer heat *MUCH* quicker than just the limited surface area of the central tube. (The latter would both mean the sand would heat up and cool down *MUCH* faster.) 6. There shouldn't be *ANY* soot buildup to speak of, as soot is unburned fuel sticking to the sides of the chimney and, as a rocket stove chimney is specifically designed to auto-ignite *everything,* it should *easily* hit the 500-600C needed to burn it away. 7. I would permanently mount the burner to a stand and the batteries to handcarts, to make moving the latter with a single person *MUCH* safer and easier. 8. Once the batter is in the house, a simple pan under it would catch any loose soot. Also, a tall chimney would create a natural draft, so the fan shouldn't be needed. (You would still want a ceiling fan to push the hotter air down to lower levels, of course.) By adding a damper to the chimney, you can more directly control how much heat is transferred to the room's air. 9. I have serious concerns about the local homeless heating their makeshift shelters here, where the temperatures can hit -40C/F, and something like this would be *PERFECT* for when it isn't safe to have a fire inside. Thank you for sharing it! Cheers!
This is a great idea, could also be used to heat water by installing a copper coil in the sand compartment and attached to a water cylinder or even the radiators in the house to heat the whole house.
I was also wondering about the copper coil as well. I've seen people use compost piles with coiled piping to heat water and also enclosed spaces. If done right with the sytem Lee has constructed, you might be able to leave the sand battery outside in its own enclosure and move the heat through insulated tubes into the house. I would use some type of high temp mineral oil but I would rule out other heat agents either. I know we live in times now where it is easy to fall prey to those peddling fear but across the planet people are finding and developing there own solutions and sharing and to me that is humanity at its best. Well done Lee.
That mesh acted like a mantle in a lamp or a room heater, much like a catalytic converter slowing down the exhaust and burning the smaller particles thus making more heat.
Yes, and no. The fire heats the air within the pipe, which heats the steel by convection. A lot of that energy goes up and out before absorption. The wire mesh captures heat which would be lost and reradiates it as IR to the pipe. Robert Murray-Smith used some fine mesh stainless steel screen to turbocharge a homemade alcohol heater (no unburned fuel present) for similar results, with a reflector added to radiate heat into the room.
Your flue appears to be straight up. This will limit the heat passed to the sand through what is called a boundary layer. This is the hot gas from the fire sticking to the walls of the flue and cooling while much hotter gas with more energy goes up the middle. What you need is a Baffle or distuptor as I call them. Something to break the gas flow up and stop it being one smooth coloumn of gas going straight up. Gas water heaters have this and I do a similar thing where I get a strip of light gauge sheet metal that just fits in the flue and then cut it alternative sides so the gas has to criss cross from one side to the other and is pushed out onto the flue walls. This Brings ALL the gas into contact with the flue which is the heat exchanger and extracts FAR more energy out of the hot gas Column. It makes a HUGE difference to the amount of material you have to burn and makes heat up much faster and more efficient. It's very simple and easy as well as cheap as it only needs some scrap metal and some cuts put in it which you bend out to disrupt the gas flow. You want to make the exhaust bounce around and slow it down a bit so it's not just ripping up and out and taking the energy with it. Very interesting design and well executed.
i have been doing something similar using sand surrounded by perlite amazing results so far the insulating properties of perlite are something else you should look into it mine is actually run on a kettle heating element run by 100 watt solar panel and the plan is to use it for a camp water heater/cooker
A really interesting experiment. I would say a very successful prototype for your chimney-less situation. The result of the chicken wire in the flue was really interesting to see. This system is very similar to my solid fuel shower installed in Bulgaria, which is basically a giant Kelly kettle plumbed into the mains water. The tank is 90 litres and provides enough hot water for 4 people to shower from one 3 gallon bucket full of small dry firewood. There were some good comments in your first video about improving the heat transfer to the sand. My suggestion for a mark II might be to consider multiple tubes through the sand (like boiler tubes in a steam engine) these would easier to clean instead of the kerplunk rods. You may well need to have a manifold to draw them together and maintain a good draft with a slightly longer flue. I would also consider lining your firebox walls with some brick or vermiculite board lining, to concentrate the burn, which may well reduce the fuel needed to charge the battery. Good luck with your next stage of the experiment, which I assume will be finding the optimum burn time to give you the required heat without burning more fuel than is necessary. I look forward to an update on your findings.
Some great ideas thank you, yes il put the chicken wire in early & see if that did actually accelerate the charging like it appeared to do & possibly see what heat I can actually get into it 👍
I’ve really enjoyed your 2 videos on your sand battery idea. Lots to think about as I’m looking to heat my workshop. One thing you might want to look at is using thermocouples to generate the power to run your fan. You might even be able to modify one of those ready made fan ones for wood stoves although they tend to suck and push warm air around which is less dense than cold air. In that respect you’ve got it right by pushing dense cold air up into the flu but anyway something to consider for a nice little mod. Thanks again.
Just an idea to improve performance, I work with Andrews and Lockinvar Gas water heaters, which use the same idea, they use baffles that drop in from the top of the flue that slow the flue gases down to more use of the heat, these baffles do just hook on the top, so are easy to remove to clean the flue.
Very nice job Lee, Have you thought about an Aluminum heat sink to slot down the top part of the flue and then just use a woodburner fan on top that would just run on the heat ? Also any update or follow up video in the pipeline 😉
If you make another, maybe try to put metal rods from the flu to the interior tank wall. I would think those rods would conduct heat from the flu into the sand a bit quicker than only radiating into the sand from the flu. Great job with this project.
Future mod. At the base of your flue pipe of the battery, instead of just running the pipe straight through, form a large cone at the bottom of the flue pipe. You’ll get a much larger surface area that will collect/transfer heat to the sand. Which should heat the battery interior much faster. This will also allow to you fab interior fins and have a larger surface area to attach them.
Thanks for sharing this with us. When the insulation reaches it's end, I would replace it with a removeable 44gal drum split & lined with much more substantial insulating material. the drum can be made better to look at by covering it up with brass fireguard mesh.
Nice :-) I built a box with aluminum gutter pipe that was insulated. Glass front.I used dryer vent tubing to run to the basement floor out the window into the box and then back out the box into the basement. It works great. I love your sand bomb :-) unbelievable how long it’s holding the heat. Would be interesting around a chimney. And it may be the answer for my geothermal greenhouse on Below Zero night thanks for sharing
A GREAT test piece. There won't be soot if the reebar is welded on the outer surface of the inner pipe. Then it will look like a hedgehog inside the gas bottle, and no holes like Kerplunk. I didn't understand where the concept of soot came from anyway. Reebar could still be fitted right through the pipe and welded on the outer surface, then the flames will lap deliciously all over the bars and the heat will really get into the sand, and equally vent plenty on the cool phase once it is indoors. As you say. Quite a lump to move about though. How about pushing a heat sensor into the sand through the steam vent? Might get temps around 500c in there. Good fun.
You’re really on to something here methinks!! I would use a rocket stove/heater setup though. FAR more efficient in both combustion and energy capture functions. Great work man!! Seriously! Please pursue it… 👍
Recommend you mount the fan at the top, blowing downward. Warm air will exit the bottom, and heat the air in your room more thoroughly. A simple improvement would be a thermostatic speed control for the fan, power for the fan could be supplied by a peltier device. The flames exiting the top while you're burning indicate that wood gases are still burning when they hit the top of the flue, possibly igniting when they hit the oxygen at the top, which means wasted energy from the fuel. Weld up an "Archimedes Screw" type spiral baffle around a length of rebar, so that it can be inserted once the fire is burning hot, and slow down the gasses on their way up. You might also add in an air feed tube coming in from the side of your firebox, and leading up the flue, which should make sure there is adequate oxygen in the flue to fully burn the wood gasses. If you really get ambitious, weld up your spiral around a hollow tube, capped at the top, with holes drilled to allow cold air to drawn from outside the firebox, and to exit into the flue/spiral. A non-burn spiral could be inserted while extracting heat to increase efficiency, and you still maintain the ability to brush the flue after every burn, keeping soot outside, and maintaining good relations with the MoD. The temp variations from bottom to top are simple. The bottom gets the full force of the flame from the fire, and gets hotter, first. The top is heated by heat coming up the flue, and by convection as the heat propogates upward through the sand. If you build another, and you KNOW you will, I'd suggest plumbing bungs (like your original steam vent) at various levels so that you can plumb in thermometers / thermocouples for precise temp measurement. Hope this helps, and looking forward to the next video.
I really like what you did. My only worry is that the radiant heat underneath the tank could scorch your floorboards. Maybe you could mount the stand on a steel plate or heat-resistant board. And then of course ad some wheels. Would love to see a video after a few months of use (including feedback from the war office).
He has a hand truck with the wheels needed. Adding wheels onto it could damage the wheels with the heat over time and might be a fire hazard keeping them so close to such a high temperwture source continuously
Yes you are right I have a re-cess at the bottom of the tank that I can put insulation in & was going to mention this in the last video & got side tracked with temperature readings, yes I also have a reflective heat mat but agree I do need some fire board also 👍
Maybe just a few stone or brick pavers to set it on. If you got the circular ones and made a pretty pattern the. I’m sure you’d get approval from the war office.
Thank you very much for recording your results. I am building a few sand batteries, as well, so it was great to see how long your unit radiated heat. Mine is a bit different in that I'll be using a metal 3 gallon pale filled with sand and heated on top of a rocket stove. (A 3 gallon bucket should hold 42 LBS of sand) I'm putting threaded rod through the bottom of the pale that stands inside the pale. My thinking is the rods should conduct heat up into the sand from the bottom, where it is heated. We'll see how it works or doesn't pretty soon.
I am curing to hear how that goes. I am looking into ways to heat my greenhouse, and was wondering about making a rocket masonry heater with a water heater filled with sand, surrounding the flue pipe. I was thinking I would use copper coil filled with water within the sand, and somehow employ a heat siphon to circulate the water under the floor or something. Of course, I want to tile the water heater and make it look like a Swedish tile stove, or at least paint it to look like one. I think tile would be better, thermal-mass-wise, and safer to touch.
Nice experiment. Still lots of different things to try for improvements. The whole sand drum to flue heat transfer system shows lots of possible efficiency improvements. A large spiral welding bead both internal and external on the flue pipe offers increase surface area an restricting for flue gas flow should increase thermal transference. Think FIrebox/Drum designs on a Boiler. Could also increase difficulty in cleaning flue pipe soot-tradeoffs? It worked way better than I thought it would. Great job.
Good stuff! To insulate fire box area, cheap old fullers earth cat litter (bentonite clay) can't be beaten, so easy to use too, simply need a double wall/skin to burn chamber, does not conduct heat, and being clay, does not burn! ✌
You could place a pizza oven , flat iron plate griddle, burned pot support, camper oven, roast marshmallows, tea pot, while charging and while it is heating the room, all that work you might as well make it multipurpose. Also have an roll of chicken side just for the inside use.
Subscriber # 444 No galvanized. 📛 toxic fumes ][so i guess just don’t sit and huff the fumes coming off the top 🥴🤤☠️][} Despite any toxic gas Seems like your intuition was correct with the chicky wire. Good thinking
I would put a granite tile on top. I have a raclette appliance with a granite top and have had a soapstone stove in the past. Both materials hold on to, then radiate heat for a long time. Pizza made on a granite surface is delicious. You can cook directly on granite.
A very real and honest project. Well done. I have been thinking along these lines but as yet, just thinking, like many others. These project seem very Heath Robinson right now, but as the fuel costs increase and it becomes a necessity of comfort/ survival, these projects will become less Heath Robinson and a lot more viable. The real crux is making these projects ‘fit’ into the modern home and sidestep the many ‘rules’ that we increasingly get imposed upon us. Ie insurance, building regs etc plus neighbours and partners, as well as trying to make them look okay. It’s a lot to ask but people are working on it and that’s the beginning of something heading in the right direction. Bravo mate.
Love this idea, I want to try to build one a bit larger but use solar panels and water heater elements to heat the sand during the day. Heat for the basement.
Have you thought of putting a top on it similar to a rain cap to spread the heated air instead of blowing straight up. I just finished a sand heater with 10lbs of compacted sand to put on my wood stove. Lol I should say tamped down as much as possible.
Thx for the video. Center pipe heating is very inefficient. Heating with an insulated pot sleeve is better. The taller the cylinder, the better. good luck.
Great videos,a real good watch. I had contemplated something like this for providing a hot air flow. I couldn't bring the unit inside myself but wondered if a coil of tubing within the sand around the exhaust pipe with an inlet and outlet would be feasible. I'm thinking that that it could stay outside and maybe a small duct fan could draw the clean air around the coil,heat it and vent it into the property. Then I guess the battery could be left 'simmering' throughout the night with minimal fuel. I'm just not sure if the the air would heat up enough though.
Great concept but have you though about making a cylinder insert for the smoke hole and design it to place in the opening but have it so the smoke and venting spirals out of the chute like a vortex in a tornado, Im thinking that might make the heating a bit more intense directing those gases upward out against the walls. Also build a frame that has wheels so you can place the canister onto the base frame and wheel it in over top the fire-pit to eliminate one extra set of listing of the canister. Could you also add open chambers inside the canister enclosed to keep sand out but allow for a fan operation to blow through the inside the the canister to better direct the heat from the sand into the room? Anyway just some thought on how to better utilize your set up to get the most out of your work. I really like the concept and plan to build one for a garage next year. based on your application making some small modifications as I outlined for you. Thanks again for sharing a great idea.
Wouldn't take much to make it look amost like a piece of furniture,maybe a carbon filter to absorb the smokey smell you mentioned.Great piece of kit you've made .
Very good idea I was thinking on that same idea but I’m thinking of using used oil and a blower as a heat source keep up the good work your mate from the U.S.A.😬
You can also use an element from something like a kettle and connect it to a Solar panel, there are several videos online showing this. For those who don’t have wood to burn. Might take longer but understand it still works.
Well Done Lee Jones, I’ve got some big ideas to utilise a large external sand battery to store daytime heat and then transfer the heat to my existing internal central heating system. I will take your wired cage idea and test how it may enhance other types of energy heat sources. You’re good I’m Norfolkngood
Dumb question here--do you think something like this could work well as a water heater? Like with a coil of copper pipe running inside the sand or something like that? Seems like if it's insulated well, the thermal mass could continue to heat up water pretty well even after the fire is out.
Best would be if the sand battery can stay outside and some heat transfer via air or water pipes to your livingroom. Great work anyway, this way people can learn from eachother and lower the energy bill.
19:10 but why did u place cooler underneath and not above the sand-heater? That way cooler just cool down the sand and send all the hot air straight to the ceiling... Do u need warm air there or on the floor? I'd placed the cooler upside down to send hot air down where it be mixed with the cold air and made the room air more pleasant to feel.
A huge amount of energy is getting wasted through that pipe. It should either have a spiral shape or multiple smaller ones spread out, preferably both. Of course it wouldn’t be so simple construction anymore but sometimes some effort pays off. Ideally the energy should be collected as far as possible by some kind of regenerator, similar to SHE (spiral heat exchanger) or something alike.
I like the idea of a sand battery and rocket stove combination, but like you would want it outside. I was thinking it could reheating the return from the central heating before it got back to the boiler, so so the boiler didn't have as much work to do. Would prefer not to have it directly connected to the system though. So would need some form of heat exchanger.
Another possible help is to use ‘turbulators, as used in radiators etc. basically a spiral that makes the gasses slow and allow a better pick up. Some fin like auger spiral.
You could hang something in the air stream and let it heat up to get a reading with your laser thermometer. Would be great if you could leave it outside and duct the air through it.
Could you put an insulated metal cap on the top to retain the heat for when the room is warmed up? Zoned out a little at the end, so maybe you mentioned it. Making sure the room is fully insulated, and putting a ceiling fan in there would probably do wonders for making the most out of the heat this generates. More efficient heat means needing to burn less wood. I think an interesting upgrade would be something like this, but heated with a heat pump overnight when electricity is cheapest. Then you could use the sand battery to keep the house warm throughout the day. Of course, you'd need the heated gas lines to run directly through the sand.
Brilliant idea . Same basic principles as a warm air unit . Heat passes over a heat exchanger and a fan blows the air through ducting to vents. You should try to come up with a duct Idea for the top pipe when it inside. So that fan just doesn't blow it straight up to the ceiling first . In fact it would fit in to the Idea of keeping it outside and keep it fired up . A rocket feed stove feed idea could be included for when you not there to check it . But well done again nice to see someone's Idea come to fruition
Maintaining house, furniture ect temp is always easier/cost efficient than heating it up. His idea of keeping the furnace from running as much with this will do just fine, and the excessive heat currently felt will be welcome come winter.
Very interesting experiment that utilized the various system constraints as well as one could do with the materials & methods available. Kudos Lee! (Being limited to burning outside of the room to be heated and having to transport thermal mass into the house manually both combine to introduce huge inefficiencies that limit the possible engineering solutions. If Lee was allowed to pipe a heated thermal transfer fluid, like mineral oil, from a backyard wood burner with a heat exchanger & a high temperature pump, then heat capture would be more efficient & continuous. Add sand batteries in the rooms to be heated and then wood burning batches could be spread out as there would always be stored heat in the sand batteries to draw from. Alas, modernity now hits us all with systemic constraints that prevent all sorts of alternative heating backup systems.) NOTE: It is also possible that the introduction of the chicken wire coil in the central chimney helped a bit by breaking up the more laminar flow of heated air & combustion gases and causing more turbulent flow which would keep the heated gases in contact with the chimney walls longer - thus transferring more heat into the sand. (The more surface area of heat exchange the better. Hope someone with heat exchanger design experience will chime in if there are any improvements that Lee could make to improve heating efficiency - especially as winter is coming on shortly.) I'd say Lee made a excellent start on a supplemental heating system that uses wood - a relatively inexpensive renewable resource. But results suggest that more heat energy will be required to get thru a cold winter and heat even a single room to a comfortable level & maintain it day after day.
Also, we handled a prolonged winter heating emergency by camping in a single room, covering the windows with homemade insulated curtains, and focusing on just keeping that room "comfortable". The rest of the house was kept above freezing to prevent pipes from bursting. A better test of Lee's system would be to prepare his winter survival room as detailed above, and then see what room temperature could be attained & maintained with his sand battery. (Especially the delta T between indoor & outdoor temperature over time.) If, with the survival room as insulated as possible, the sand battery can create comfortable air temp for a number of hours, then maybe all that will be needed is a second sand battery that can be charging while the first one is discharging. As some have suggested, a metal insert in the sand battery chimney that increases turbulent flow and conducts more heat to the chimney wall could help improve heat exchange. But then there is the challenge of transferring that heat into the sand. Again, someone expert in heat exchanger engineering needs to chime in on how to get that heat into the sand more efficiently. (A simple, inexpensive solution that improves thermal storage sufficiently to make it worthwhile to implement.)
Hi enjoyed your sand heater design, Matchine Mart sell heat powered stove fans maybe ideal for application, I would worry about your wood floors sit on top of concrete slab or heat resistant tiles,
Fck brilliant idea mate ! Would be interesting with a rocket stove still burning chamber ! It would boost the heating process with tiny pieces of woods !
@@leejones2511 I did but the last time you said anything was at 5 hours, but you acted like it was still going strong. I wasn't to know how long before depleted. Did it last all night how about the next day was it still going. I've heard great things, but I don't have one.
@@vonries yes after 7 hours it's still 70-100c depending on the burn time to charge, I'd say at 10 hours it's going to be in the 50c bracket which if you had it in a small room will still be efficient,
When are you launching? LOL It looks like a old time satellite. Great video. I ran on a bit in your first video on this. You did a nice job on insulating. On looking though, you already have radiator heat. You can't do much better than that. If it is a closed system, replace the water will oil, and heat transfer increases like 7 times. I know your wife will want the satellite to not be filling the center of the room. Try the Trombe Wall I talked about in your first video. It will heat free with the sun as hot as you are getting now with a fire.
Awsome project. I'm looking to do the same at a larger scale with a thebaddition of a water heat exchanger and a radiator in the house. I found your channel while doing some homework. Is the system working for you? I believe the chicken wire is causing turbulent flow in the flue allowing better transfer of heat. I deal with this at work with water cooled molds. When we have overheating issues, baffles are added to create turbulence and increase heat transfer. If you add a cap to the flue to direct the air horizontally, it might make the room feel warmer. As it is, it seems as though the heat is being directed to the ceiling and the cool air is settling where your thermometer is located.
Any chance you'd be willing to make a blueprint of this, something we could download, print and take to someone with welding equipment? I could use something like this to heat up some spaces where my wood stove can't reach. My spaces are way smaller, so maybe this is a bit much, but this feels like exactly like what I've been looking for.
I think if you can keep it on the Sack Truck (Hand Truck) for heating and leave it on that indoors would make this a one person job. You take it outside heating up on the Sack Truck, then pul it back off the heat and roll it right indoors into position would be a game changer. Simple, effective and with one person efficient. Overall that would be safer too.
How long did the first burn test last in hours before reaching a comfortable room temperature and you can basically touch the chicken wire without being burned?
Chicken wire was only hot at the top & bottom basically where it was traveling through where it was clamped to the body the rest was warm, I went to bed at 12am & was still warm but able to put & hold your hand on it, as in the flue & handle so 12 hrs
theres endless upgrades you could do with this but top of my list would be to introduce hot fresh air to the smoke. any smoke exiting the chimney is unburned fuel and lost potential heat. i'd add a slight narrow point in the chimney, about 1/3rd of the way up. (like in a carburettor) and pipe in some pre-heated air so the smoke ignites in the chimney.
hi back in the 1920s my grandma used this type of thing same idea ....biscuit tin heated on solid fuel cooking wrapped in towel made good bed warmer...better than hot water bottle plus put food into pot inside pot with sand and heat made good slow cooker john
Great job. Maybe if you had removable insulation that you could take off when you get it indoors, you would get a better distribution of heat to heat the room quicker. Also would like to see a video of you moving it onto the sack barrow. The video you referred to in the previous video is Robert Murray Smith. His channel is fantastic.
Yes you are probably right I got effective heat from the flue up until about 9pm & then it felt like it tailed off but the flue & handle was still to hot to touch & (which is amazing) & was still hot but touchable at midnight! But problem with insulation is it's really messy but il see if I can get a product to go on the inner part of the insulation that can withstand the heat & make a jacket of some kind, But il get some thermometers first & check how it tails off from the flue & do a video on that & yes il include a transfer clip of it being moved, Yes thats him Robert Murray Smith 👍
Very interesting! Made a rocket stove sand battery that released heat for 5 hours but have been thinking about how an insulated jacket would improve the design. BTW, did you use standard rockwool?
No I got ceramic insulation, hi temperature as I didn't want to risk a smell , not that I'm saying rock wool or other insulation will smell, it's just that this one said it doesn't so I'd went with is to save me doing it twice 👍
Make a box out of glass foam about 180 mm thick. Put a plate steel floor inside the box to distribute the weight. Stack firebricks inside, tied together with fencing material or chicken wire, like a gabion fence. Put a resistance heater in it. Use a solar panel or a small wind turbine to power the resistance heater. Select the resistance for maximum power transfer. The heat will leak through the glass foam insulation at a rate that is dependent on the temperature of the bricks. Continue to use your home heating system and thermostat the same as before. The heat that leaks through the glass foam insulation into the house interior will reduce the amount of fuel you have to buy for the conventional system.
hello big chap good to see a normal human giving it a bash I'm looking to do this, but with 'starlite' for insulation. have a look on nighthawklight's channel. very impressive will let you know
You don't seem to be getting the full rocket stove effect with the secondary burn in the chimney (for which you need air injection further up the flue). Could you run a pipe or two from the exterior at the bottom up the chimney to about halfway? That would inject heated air into the hot gassed and complete the burn. Possibly a taller removable chimney would get the roar really going. And more air to the bottom of the fire? A ring of holes around the bottom of the firebox? I heat with a wood stove, so I know adding air to a stove through a door gets you a slower fireplace type burn--while having the door closed and the air blasting into the base of the flame through narrower holes, gets the fire really honking! Seems bloody effective as it is though! Hell of a job!
Not sure if you thought about it but you could use a fireplace fan -- energized by heat no electricity and would circulate the heat coming up from the pipe.
Have you thought of building a rocket stove to heat the can? It might use less heat. Also, over there in the UK, do people use big water heaters with large tanks, or maybe a steel drum would work? I was thinking you could set a large cylindrical metal vessel on a granite tile on the floor with some bricks in it, maybe on a metal stand with feet, like for flower pots. Then, you could lower your sand battery into it. It would heat the air in the container. Since I am a lady who likes pretty things, I would tile the container, which would accomplish two things: it would be decorative, like a Swedish tile stove, and it would add some more thermal mass for radiating into the room.
What a Good idea to use chicken wire Mesh in Tue chimney, Just the thing I needed to know for my stainless steel Steam boiler of about the same design ,
Consider adding a damper on the top of the chimney to restrict the fumes allowing more heat transfer and slower burn of the wood. Yes an open chimney will burn hotter and faster but inn this case a slow 300C burn will save you wood and will make the overall project more efficient as you are losing less heat.
When we had a power cut for several days last year I heated water on my outdoor wood fire and carried it inside in 10 and 20 litre plastic cans. HDPE plastic doesn't melt until 130C so it's quite safe for hot water. You can drape wet clothes over the cans and they dry in no time. Water holds 5 times as much energy as sand so they heat commercial sand batteries to about 500C which takes as much energy as heating the same mass of water to 100C i.e. boiling. I'm a bit miffed about the amount of energy you're losing up the chimney of that heater. Given the size of the flue compared to the size of the firebox and its central position I reckon 50% of the heat energy in the wood is being wasted. If you welded something to the top of the flue to hold a pan or steel bucket you could heat water with the exhaust heat and just put it in the bath or sink or as I say in an HDPE can. I use a 25 litre brass tub which used to hold coal. Softwood gives out more heat than hardwood in a given time because it burns faster so you need to split hardwood really small.
I would expect that if you were to take a piece of insulated pipe with a bend in it and it were to reach close to the floor where you can use that fan upside down to drive the air across the floor, then it should make it hotter for more air space as you're heating the air from the floor up not just the top of that sand box up. You might even consider ducting some of that hot air up at ceiling level into another room if it's too hot like you say. Firing it so the transfer to the house at near night fall would surely drive the temps up for the entire night. It appears to be a very good solution to the energy bill issue. well done.
Mate, blinding! 'I did that all on my own' ......yeah, Robert Murray-Smith is an inspiration eh! Fair play, see all good ideas on developing and id suggest really dialling down on heat transfer via oxygen control, burn lower longer using less fuel and gather more heat
