The most effective masonry heater I've experienced was at my aunt & uncle's house in Minnesota, and I was kind of amazed by it as a kid. It actually drew cold air from outside the house rather than warm air from inside. As my uncle explained, 'if you let it draw from inside the house, the house will suck in the cold outside air anyway to replace that, so you may as well draw it directly from outside." I never knew exactly how the inside of it worked, but I remember it taking an armload or two of wood in the bottom chamber and a few sticks in a tiny upper chamber. You had to light the upper chamber first and let it burn for fifteen minutes before lighting the bottom chamber. It didn't *seem* to be getting hot at all - the outside of the heater was only a couple dozen degrees fahrenheit warmer than the house. But two armloads of wood (and a handful of sticks) kept it warm for four or five days. The chimney didn't seem to smoke at all, and there was hardly any ash left when it was time to light the next fire.
It would be nice to be able to control. Sometimes it is nice to have the fire pull fresh air into the room too. When it gets super cold, though, the ability to switch to mostly drawing from the outside directly into the heater would be nice.
Thanks - really interesting ;-) How I see it and think it is/was: The reason for the older model's different design is that previously they did not use the type of ceramic insulation that we have and can use today. In order to achieve some form of insulation between the channels, the wall thickness was therefore increased in some places in the older model. The outer metal barrel set a limitation, so therefore the wall thickness of the internal channels had to be set according to the best possible judgement. I therefore believe that we must take this into account when we want to develop a new model based on old experiences. In the new improved model, we should take into account both the physical "laws" and properties, and recent experience for each individual component. We want to achieve as good a draft in the oven as possible and at the same time as good a utilization of the heat energy as possible. Design principles can therefore be: Every time the flue gas rises, we regard it as a chimney where we want as high a speed as possible and with as little heat loss as possible, because a heat loss in an upward flue gas will slow down the flue gas because the density increases, i.e. we insulate the chimney. Because we work with a closed system, each section, i.e. an upward or a downward section, should be seen separately. Every time the flue gas is cooled, we want this to take place when the flue gas is in a downward direction, because the cooling increases the density and therefore cooling in a downward direction helps to increase the draft in the furnace. (Large cross-sectional area and large volume in the downward channel is desirable, and relatively large wall surface with good thermal conductivity and large thermal mass. The large volume gives the flue gas time to release heat. Think: bell). There may (probably) be a need to use a shunt damper when the oven is started. And perhaps also one or more other dampers if the stove is built in an area with very low winter temperatures, because when it is extra cold outside you can actually allow the flue gas to be cooled a little more and still have a heat surplus (differential temperature, i.e. temperature difference between bottom and top of the chimney ) to drive the flue gas up through the chimney. On the other hand, this will also complicate the use of the stove, so it is probably worth considering how much it should be optimized because if you do not understand how to use the stove, you will end up with smoke in the house. And thank you for the description of why you remove the glowing coals from the stove. I'm thinking whether you could make a system where you can push the glowing coals into a small, separate mini-furnace, which is airtight (i.e. carbon monoxygen-tight) in relation to the house. But if it can't be made carbon monoxide safe, it's probably better to carry the glowing coals outside as you showed. You showed in a previous video "Finnish masonry heaters. -The baking oven. Part 2." , that this oven has a secondary combustion chamber, and now I understand even better the significance of this.
I basically agree with everything you said. Yes, using modern insulating materials would would allow the space to be re-thought and optimised. Absolutely possible to make the ash-compartment double as a secondary chamber with it's own small flue (bypassing the baffle) to draw off CO as in my big baking oven thereby allowing baffles to be sealed at the optimum point. I think that when you said 'shunt damper' you mean a bypass or summer damper. This goes without saying. Almost all fireplaces and heaters have that here. In addition I want to take a much harder look at the material used as thermal mass and create the best combination of fast and slow heat absorbers/releasers. I think there is a lot of potential for some major improvements in performance.
Man, the more you want to geek out on these masonry heaters, the happier you’d make me! (I’ve been experimenting with the ash-corrosion resistance of aluminosilicate/zirconia-mullite refractory materials myself for masonry heater fireboxs - and I would love to see your idea of building a new/optimized version of one of these!) Very happy to be newly subscribed to your channel. Cheers!
I'm curious whether the exhaust is as clean on the 2nd burn as the first, what the temperatures are on the exhaust and whether they're using the same amount of wood (I apologize if you said this last and I just didn't catch it). Part of the point of the rocket mass heater is to have a very clean burn. It would also be interesting seeing a head to head of a this against the same amount of wood in a well designed rocket mass heater (could be someone else's) as a comparison. How heavy is this? The small footprint is appealing for certain situations. I suspect like other masonry heaters it would require some remodeling for support to add to an existing home.
It weighs around 800kg so it definitely needs a good foundation. No, the exhaust on the first burn is much cleaner. This is something that I find a bit annoying about the Rocket mass heater community and the way they use this term 'clean efficient burn' This just means you extract the maximum amount of heat from the wood and that the exhaust is cleaner but says absolutely nothing about how efficiently the heat is actually used, how much heat is lost up the chimney etc. This is why I wanted to show this test, to show that a much less 'efficient' burn can actually be far more efficient in terms of useful heat. I am planning a RMH project so I may be able to do that side by side comparison myself!
The thing that pönttöuuni is lacking would be a separate compartment to pull the coal in to smoulder. With a separate by-pass damper like in the big baking ovens (leivinuuni).
great video! passion and experties clearly on display:) where did you find the old schematics? i've been googling in quite a few ways(in finnish) with not much luck...
I love this subject! When I was on vacation in Sirkka in northern Finland we had two big fireplaces. The one upstairs didn't work that well, it had glass doors that apparently needed to stay open when burning. But I found out about the chimney being connected to the underside and was really surprised by that. At first I just thought it wasn't a working fireplace. But very interesting to see they are specially build to slowly release heat. Which is to be expected in a climate where -30 isn't uncommon.
когда я был маленьким ребенком у нас было 2 дома здесь в россии и в одном доме печь сложил мой отец. так вот когда ее топили не дровами а углем но все же приходилось нередко открывать окна зимой для проветривания) печь была в целом обычной угольной печью с вертикальной засыпкой угля но вот дымоход был длинный и шел вдоль двух стен разделяющих дом на комнаты.да именно так не одна стена с каналами в ней а дымоход делился на 2 таких стены по сути образующих угол. стены хорошо грелись в которых был дымоход и как следствие очень хорошо грели комнаты. и не дай бог вам забыть закрыть задвижку дымохода и дать печи гореть на максимум.....чугунная плита под которой горел уголь разогревалась до красна.и приходилось зимой охлаждать дом открывая окна))) и да дом был неутепленный только выполнен по технологии смешивания глины+ солома. саманный дом или вроде того. да в те времена уголь был довольно дешевый в нашем добывающем уголь городе) а во 2 доме печь была похожей конструкции и так же дымоход делился на 2 и грел 2 стены но печь плохо горела и плохо грела....ее не мой отец делал) но помню до сих пор как в 90е годы был ребенком и стоял ночью смотрел на красную раскаленную печку и нельзя было близко к ней подойти изза сильного жара. так что важно правильно рассчитывать определенные параметры печи чтобы она хорошо горела и грела.
Your infrared themometer is seeing a reflective metal surface, which includes cooler images lowering your overall reading. The wall is much less reflective surfac e giving a more accurate reading
Very interesting, thank you. I particularly appreciate your diagrams. Perhaps the chief lesson here is that excess air might drive an impressive blaze but is also pushing heat up the chimney (not to mention pulling cold air into the house to replace it). I have a question about construction - how do you get the metal case over the brick lining - have you very high ceilings, or is it in sections that can be dismantled? I struggled to even get an oil drum over a tall rocket riser because of the ceiling and would appreciate any tips. Thanks again 👏💯
Exactly. That is what I meant when I said I have problems with the term 'efficient burn' Fast and hot may be very efficient at getting the max heat from the fuel and minimising emissions but It can be very inefficient in terms of giving 'useful' heat . The pönttöuuni is built in sections with each section measuring 60cm in height. Place the section, build the brickwork inside...and a bit higher, then next metal section in place. repeat.
@@batchrocketproject4720 Well as I said, here in Finland they produce the metal shells, 80cm in Diameter, 60 cm tall sections that lock together. They are quite lightweight but a bit bulky for shipping I guess. I could make some enquiries, I am sure they would ship internationally.
@@downdirty9642 burn slow as you do by restricting air for fuel (wood), but add little extra air just above tulipesä to burn unburnt gasses for cleanliness. one of your drawings had somewhat this idea
@@downdirty9642 Thank you for the offer but I like to build from common items. Oil drums are close to 60cm diameter but create the headroom problem during installation, so I will experiment with reliable methods of cutting and joining them.
I agree with your dislike of the use of the term “efficient burn” i think a more appropriate term would be “clean burn”. Efficiency is used to rate a process. Now if breaking down wood to ash is the process, then I suppose it is the most “efficient burn” but if the process is to extract heat, then no it is NOT the most efficient burn with this size stove, as you have demonstrated. Heat transfer is about temp difference, surface area and contact time, and turbulence(breaks down laminar flow). If you are roaring a ton of air thru the stove, you are reducing the contact time of the hot gas to the transfer surface of the stove mass. To compensate for less contact time, the surface area would have to be increased dramatically… And unless you are really monitoring it closely, you can be adding too much air which will actually reduce the hot gas temperature… Here is where the use of pelletized fuels really has potential IMO, because you can reduce the size of the fire and the volume of hot gas created, but still employ that very clean burn, to allow a no smoke operation but still collect a large volume of heat per pound of fuel burnt in a reasonably sized stove. This sized stove would probably work really well with a small hopper and and gravity fed pellet burner in place of the door. You fill the hopper, light the stove and let it roar away heating the mass. A simple photocell looking at the flame could control the intake damper. When it detects flameout when the fuel is expended, it seals the intake damper to stop internal airflow and the draft cooling the mass from the inside and it sets and radiates heat. Drawing combustion air from within the dwelling is really counter productive. It creates negative pressure which draws in cold air thru every leak in the envelope toward the low pressure. A better methodology in my experience is to A. Completely seal/isolate the combustion process from the room and draw combustion air ONLY from outside the heated envelope. B. Provide a second small outside air source using a small fan to the heater and blow fresh air directly upon it. This will create a positive pressure hot air source originating at the heat source, forcing the coolest air in the room out near the walls, back out thru the leaks in the envelope. WAY more comfortable… a similar flame-out detect, or a firebox temp sensor to control the intake air damper would make it a more fire and forget type operation. Load with fuel, open inlet damper, light stove, once to burn temp, the damper close goes active and once the fire box temp drops below a certain temp, it automatically closes the intake damper so the stove can set and radiate. The fresh room air source could be controlled by the same temp sensor so it only runs while the stove is burning… Have run pellet and conventional wood stoves this way and bringing outside air directly to the stove for combustion and to create positive pressure make a world of difference in dwelling comfort… Great video, geeks make the world go around:)
Very interesting, I came across your channel and had to rewind at points to catch what was beening put across. Great seeing how your heater worked but one question. Have I have missed something. In test one and two what was done to achieve the different results as you stated "people say there's only one way to start it -but there are many " however you haven't said which way you were using in both and at the end got confused by how test 1 was and then test 2 was but no explanation why the different time line , also left and right pictures were shown with crosses but no temperature identification so confusing me to what we were seeing.
So, i think the jist is, doors open = higher peak temp, but more heat washed away up the chimney Controlled burn = slightly lower peak temp but more heat for longer Does the increased temp of the open doors 'efficient burn''mean less nasties overall in the flue gases?
If I may I'm operating 2 coal stoves a stoker and a hand fired. 3rd and 5th year. To burn efficiently I've been a gusting them like a carburetor . Could you make an adjustment on the wide open stove buy closing one door and adjusting the other door . The other stove seal the door tite and leave the ashes.
I have absolutely no experience with any coal fired heater/stove. I think it is probably 20 years since I have seen a piece of coal! So I am sorry, I cannot help you with this.
This is the problem. This particular heater is in a 14m2 room but it cannot be viewed in isolation, It is just around the corner from the baking oven, in the other direction there is the sauna stove on the other side of the wall. They all work together to heat the space. I wish it were so simple.
As someone with some experience with Finnish masonry heaters, the temperatures are really not even supposed to go very high. The point is that you only burn like at tops twice a day, and when it is not that cold maybe only three times a week. And that mass will store the heat, releasing it slower. The original concept of using mass to store heat is literally thousands of years old and used in Saunas long before any written records of it.
Just surrounding my wood stove with 1500 lbs of concrete paver mass has made a difference for me. It really evens out the heat spikes and probably saves me a little firewood as well.
I remmember that when i grew up and we go visit grandpa then he had a house buid in 1865 from natural stones and wall thickness about 80cm - he had also this type (round and tall) he had to burn it every second dat when outside was -25C id was about 1m in diMETER nd from that gases was also going true a brick heat battery/wall wat was heated from both sides - from kithsen stove and from the "rocket" one... - they are good and efficient I heard that that was masons secret how to make them and at it was been used local stones for heat acumulation - can not confirm if the stones was used - I'm 43 now and they still going fine......
Very nice, thank you. The Pönttöuuni reminds me of the Utermark stove, which was developed in the Russian empire in the 1820s (ru.wikipedia.org/wiki/Печь_Утермарка ). I think that's where the idea of the metal sheet came from, as Finland was part of the Russian empire at the time. The Utermark stove had several up and down channels to maximise thermal efficiency by getting the last bit of heat out of the exhaust gases.
For some reason the link does not work. Probably our idiot government blocking anything Russian. I'll check out the Uttermark stove though. Thanks for the tip!
@@downdirty9642 I don't know where the idea for the metal clad ones came from, but I was under the impression that tiled ones became popular in manor houses in Sweden some time around the 1700's... Which would also explain why these types of heaters are common in both Finland and Sweden, as that would predate the period of Russian occupation (1809-1917).
What's always puzzled me about such stoves is how do to clean all the passages within it? Surely there is a need to get a brush in there to sweep them periodically?
Very interesting comparison . The reason why on the left with full burn all the time surface temperature was lower may be because the speed of flue gases was too high. I am going also to build masonry heater. Do you have experience with rocket masonry heater - batchrocket with heat riser, vortex? Could be big difference between "classic" fireplace with afterburn chamber and any rocket stove? In terms of clean burning , flue temperature and total amount of heat from the same amount of wood.
I would also suspect that having the hatch fully open, you get plenty of excess air. Ideally you would want flue gas with minimal amount of remnant O2. One should keep in mind that most of the gas (both intake and exit) is N2, wich is mostly inert and does not contribute to the burn, but will transfer heat up the chimney. So any volume of excess air is effectively more than doubled. But on the other hand, with solid fuels you typically still want some remnant O2, because before it would reach zero, you usually get unburnt fuel in the form of carbon monoxide, soot and tar. I have done some tinkering around with a flue gas analyzer. At one point I literally spent hours and hours with a 350 kW boiler with a wood pellet stoker. It was quite interesting actually, but took a lot of waiting, as I quickly learned that when burning wood based fuels making any adjustment will take some time before the burn will reach a new equilibrium state.
The name sounds and spells Finnish, they are popular in Sweden, I lived in a house in Sweden with five rooms and one of those in every room. Although mine where white in colour.
Per my comment below,.... the draft is very impressive, but that's because of the extremely long riser in that giant metal tube. A "J" rocket will draft like that on a small, 3 foot (or less) riser. Please see my comment below on the website you must see.
Great subject. Few issues, however. Please lose the music. It is not necessary and it is cripplingly annoying. Also you have sound problems. Most of the time I could not hear what you were saying, even at max sound settings
for f sake kakelugnar has been in sweden since 1700 get you facts right and its not from russia its from italy get your facts straight from beginning from pot stoves and we in sweden did innovate the tile stove in 1700 wow so russia has nothing to do with this or findland sorry
Heads up, taking this kind of tact regardless of how annoyed you happen to be is very likely to backfire on anyone who reads it. I have no horse in this race and yet I want to tell you to f off with the attitude and I'm all for learning new facts.
The most effective masonry heater I've experienced was at my aunt & uncle's house in Minnesota, and I was kind of amazed by it as a kid. It actually drew cold air from outside the house rather than warm air from inside. As my uncle explained, 'if you let it draw from inside the house, the house will suck in the cold outside air anyway to replace that, so you may as well draw it directly from outside." I never knew exactly how the inside of it worked, but I remember it taking an armload or two of wood in the bottom chamber and a few sticks in a tiny upper chamber. You had to light the upper chamber first and let it burn for fifteen minutes before lighting the bottom chamber. It didn't *seem* to be getting hot at all - the outside of the heater was only a couple dozen degrees fahrenheit warmer than the house. But two armloads of wood (and a handful of sticks) kept it warm for four or five days. The chimney didn't seem to smoke at all, and there was hardly any ash left when it was time to light the next fire.
Sounds like a good one!
Cool story
It would be nice to be able to control. Sometimes it is nice to have the fire pull fresh air into the room too. When it gets super cold, though, the ability to switch to mostly drawing from the outside directly into the heater would be nice.
This had been standard in European wood-burning heaters for quite a long time.
I wonder if lighting the upper chamber first was to start the air flowing through the inlet, stove, and chimney well, before the main fire was lit.
Thanks - really interesting ;-)
How I see it and think it is/was:
The reason for the older model's different design is that previously they did not use the type of ceramic insulation that we have and can use today. In order to achieve some form of insulation between the channels, the wall thickness was therefore increased in some places in the older model. The outer metal barrel set a limitation, so therefore the wall thickness of the internal channels had to be set according to the best possible judgement.
I therefore believe that we must take this into account when we want to develop a new model based on old experiences.
In the new improved model, we should take into account both the physical "laws" and properties, and recent experience for each individual component.
We want to achieve as good a draft in the oven as possible and at the same time as good a utilization of the heat energy as possible.
Design principles can therefore be:
Every time the flue gas rises, we regard it as a chimney where we want as high a speed as possible and with as little heat loss as possible, because a heat loss in an upward flue gas will slow down the flue gas because the density increases, i.e. we insulate the chimney.
Because we work with a closed system, each section, i.e. an upward or a downward section, should be seen separately.
Every time the flue gas is cooled, we want this to take place when the flue gas is in a downward direction, because the cooling increases the density and therefore cooling in a downward direction helps to increase the draft in the furnace. (Large cross-sectional area and large volume in the downward channel is desirable, and relatively large wall surface with good thermal conductivity and large thermal mass.
The large volume gives the flue gas time to release heat. Think: bell).
There may (probably) be a need to use a shunt damper when the oven is started.
And perhaps also one or more other dampers if the stove is built in an area with very low winter temperatures, because when it is extra cold outside you can actually allow the flue gas to be cooled a little more and still have a heat surplus (differential temperature, i.e. temperature difference between bottom and top of the chimney ) to drive the flue gas up through the chimney.
On the other hand, this will also complicate the use of the stove, so it is probably worth considering how much it should be optimized because if you do not understand how to use the stove, you will end up with smoke in the house.
And thank you for the description of why you remove the glowing coals from the stove.
I'm thinking whether you could make a system where you can push the glowing coals into a small, separate mini-furnace, which is airtight (i.e. carbon monoxygen-tight) in relation to the house. But if it can't be made carbon monoxide safe, it's probably better to carry the glowing coals outside as you showed.
You showed in a previous video
"Finnish masonry heaters. -The baking oven. Part 2." ,
that this oven has a secondary combustion chamber, and now I understand even better the significance of this.
I basically agree with everything you said. Yes, using modern insulating materials would would allow the space to be re-thought and optimised.
Absolutely possible to make the ash-compartment double as a secondary chamber with it's own small flue (bypassing the baffle) to draw off CO as in my big baking oven thereby allowing baffles to be sealed at the optimum point. I think that when you said 'shunt damper' you mean a bypass or summer damper. This goes without saying. Almost all fireplaces and heaters have that here. In addition I want to take a much harder look at the material used as thermal mass and create the best combination of fast and slow heat absorbers/releasers. I think there is a lot of potential for some major improvements in performance.
Man, the more you want to geek out on these masonry heaters, the happier you’d make me! (I’ve been experimenting with the ash-corrosion resistance of aluminosilicate/zirconia-mullite refractory materials myself for masonry heater fireboxs - and I would love to see your idea of building a new/optimized version of one of these!) Very happy to be newly subscribed to your channel. Cheers!
I'm curious whether the exhaust is as clean on the 2nd burn as the first, what the temperatures are on the exhaust and whether they're using the same amount of wood (I apologize if you said this last and I just didn't catch it).
Part of the point of the rocket mass heater is to have a very clean burn. It would also be interesting seeing a head to head of a this against the same amount of wood in a well designed rocket mass heater (could be someone else's) as a comparison.
How heavy is this? The small footprint is appealing for certain situations. I suspect like other masonry heaters it would require some remodeling for support to add to an existing home.
It weighs around 800kg so it definitely needs a good foundation. No, the exhaust on the first burn is much cleaner. This is something that I find a bit annoying about the Rocket mass heater community and the way they use this term 'clean efficient burn' This just means you extract the maximum amount of heat from the wood and that the exhaust is cleaner but says absolutely nothing about how efficiently the heat is actually used, how much heat is lost up the chimney etc. This is why I wanted to show this test, to show that a much less 'efficient' burn can actually be far more efficient in terms of useful heat. I am planning a RMH project so I may be able to do that side by side comparison myself!
The thing that pönttöuuni is lacking would be a separate compartment to pull the coal in to smoulder. With a separate by-pass damper like in the big baking ovens (leivinuuni).
FYI in Russia this kind of stoves is called "голландка" (a holland stove), the round metal cased subtype frequently called "стояк" (a riser)
Thanks for geeking out - please continue...and kindly do a review of that interesting looking masonry heater wall
great video! passion and experties clearly on display:) where did you find the old schematics? i've been googling in quite a few ways(in finnish) with not much luck...
This is fascinating and thank you for sharing.
I love this subject! When I was on vacation in Sirkka in northern Finland we had two big fireplaces. The one upstairs didn't work that well, it had glass doors that apparently needed to stay open when burning. But I found out about the chimney being connected to the underside and was really surprised by that. At first I just thought it wasn't a working fireplace. But very interesting to see they are specially build to slowly release heat. Which is to be expected in a climate where -30 isn't uncommon.
Great video, love the side by side test, and would love to see a comparison between new and an old sand trapped stove!
very helpful. Thank you.
Glad it was helpful!
Kiitos videosta!
Thanks for the knowledge. Gets my brain ticking over
If I had the financial ability I would fund your research. Thanks for the useful info. God bless
I appreciate that! Glad you found the video useful.
Thanks, that was an interesting and a well explained and edited video.
когда я был маленьким ребенком у нас было 2 дома здесь в россии и в одном доме печь сложил мой отец. так вот когда ее топили не дровами а углем но все же приходилось нередко открывать окна зимой для проветривания)
печь была в целом обычной угольной печью с вертикальной засыпкой угля но вот дымоход был длинный и шел вдоль двух стен разделяющих дом на комнаты.да именно так не одна стена с каналами в ней а дымоход делился на 2 таких стены по сути образующих угол. стены хорошо грелись в которых был дымоход и как следствие очень хорошо грели комнаты. и не дай бог вам забыть закрыть задвижку дымохода и дать печи гореть на максимум.....чугунная плита под которой горел уголь разогревалась до красна.и приходилось зимой охлаждать дом открывая окна))) и да дом был неутепленный только выполнен по технологии смешивания глины+ солома. саманный дом или вроде того.
да в те времена уголь был довольно дешевый в нашем добывающем уголь городе) а во 2 доме печь была похожей конструкции и так же дымоход делился на 2 и грел 2 стены но печь плохо горела и плохо грела....ее не мой отец делал)
но помню до сих пор как в 90е годы был ребенком и стоял ночью смотрел на красную раскаленную печку и нельзя было близко к ней подойти изза сильного жара.
так что важно правильно рассчитывать определенные параметры печи чтобы она хорошо горела и грела.
Just found this and it's interesting. Thanks!
Fascinating, thankyou for the insight into these beautiful stoves, here in Wales im wondering what the next stove i build will look like.
Your infrared themometer is seeing a reflective metal surface, which includes cooler images lowering your overall reading. The wall is much less reflective surfac e giving a more accurate reading
Ok, thanks for that!
Very interesting, thank you. I particularly appreciate your diagrams. Perhaps the chief lesson here is that excess air might drive an impressive blaze but is also pushing heat up the chimney (not to mention pulling cold air into the house to replace it). I have a question about construction - how do you get the metal case over the brick lining - have you very high ceilings, or is it in sections that can be dismantled? I struggled to even get an oil drum over a tall rocket riser because of the ceiling and would appreciate any tips. Thanks again 👏💯
Exactly. That is what I meant when I said I have problems with the term 'efficient burn' Fast and hot may be very efficient at getting the max heat from the fuel and minimising emissions but It can be very inefficient in terms of giving 'useful' heat . The pönttöuuni is built in sections with each section measuring 60cm in height. Place the section, build the brickwork inside...and a bit higher, then next metal section in place. repeat.
@@downdirty9642 Thanks. If only they made full-width, 60cm tall oil barrels. I'll have to try a way of cutting and joining them without leaks.
@@batchrocketproject4720 Well as I said, here in Finland they produce the metal shells, 80cm in Diameter, 60 cm tall sections that lock together. They are quite lightweight but a bit bulky for shipping I guess. I could make some enquiries, I am sure they would ship internationally.
@@downdirty9642 burn slow as you do by restricting air for fuel (wood), but add little extra air just above tulipesä to burn unburnt gasses for cleanliness. one of your drawings had somewhat this idea
@@downdirty9642 Thank you for the offer but I like to build from common items. Oil drums are close to 60cm diameter but create the headroom problem during installation, so I will experiment with reliable methods of cutting and joining them.
Yes please & thanks
ok.....and thanks!
I agree with your dislike of the use of the term “efficient burn” i think a more appropriate term would be “clean burn”. Efficiency is used to rate a process. Now if breaking down wood to ash is the process, then I suppose it is the most “efficient burn” but if the process is to extract heat, then no it is NOT the most efficient burn with this size stove, as you have demonstrated. Heat transfer is about temp difference, surface area and contact time, and turbulence(breaks down laminar flow). If you are roaring a ton of air thru the stove, you are reducing the contact time of the hot gas to the transfer surface of the stove mass. To compensate for less contact time, the surface area would have to be increased dramatically… And unless you are really monitoring it closely, you can be adding too much air which will actually reduce the hot gas temperature… Here is where the use of pelletized fuels really has potential IMO, because you can reduce the size of the fire and the volume of hot gas created, but still employ that very clean burn, to allow a no smoke operation but still collect a large volume of heat per pound of fuel burnt in a reasonably sized stove. This sized stove would probably work really well with a small hopper and and gravity fed pellet burner in place of the door. You fill the hopper, light the stove and let it roar away heating the mass. A simple photocell looking at the flame could control the intake damper. When it detects flameout when the fuel is expended, it seals the intake damper to stop internal airflow and the draft cooling the mass from the inside and it sets and radiates heat.
Drawing combustion air from within the dwelling is really counter productive. It creates negative pressure which draws in cold air thru every leak in the envelope toward the low pressure. A better methodology in my experience is to A. Completely seal/isolate the combustion process from the room and draw combustion air ONLY from outside the heated envelope. B. Provide a second small outside air source using a small fan to the heater and blow fresh air directly upon it. This will create a positive pressure hot air source originating at the heat source, forcing the coolest air in the room out near the walls, back out thru the leaks in the envelope. WAY more comfortable… a similar flame-out detect, or a firebox temp sensor to control the intake air damper would make it a more fire and forget type operation. Load with fuel, open inlet damper, light stove, once to burn temp, the damper close goes active and once the fire box temp drops below a certain temp, it automatically closes the intake damper so the stove can set and radiate. The fresh room air source could be controlled by the same temp sensor so it only runs while the stove is burning… Have run pellet and conventional wood stoves this way and bringing outside air directly to the stove for combustion and to create positive pressure make a world of difference in dwelling comfort… Great video, geeks make the world go around:)
I’ve seen some ones who had the ash collection tube in the basement to keep that one defrosted as well
Yes, I have heard of those also.
Just discovered your channel. Great content! Would love to see more info on the modern versions as well.
Very interesting, I came across your channel and had to rewind at points to catch what was beening put across.
Great seeing how your heater worked but one question.
Have I have missed something.
In test one and two what was done to achieve the different results as you stated "people say there's only one way to start it -but there are many " however you haven't said which way you were using in both and at the end got confused by how test 1 was and then test 2 was but no explanation why the different time line , also left and right pictures were shown with crosses but no temperature identification so confusing me to what we were seeing.
So, i think the jist is,
doors open = higher peak temp, but more heat washed away up the chimney
Controlled burn = slightly lower peak temp but more heat for longer
Does the increased temp of the open doors 'efficient burn''mean less nasties overall in the flue gases?
If I may I'm operating 2 coal stoves a stoker and a hand fired. 3rd and 5th year. To burn efficiently I've been a gusting them like a carburetor . Could you make an adjustment on the wide open stove buy closing one door and adjusting the other door .
The other stove seal the door tite and leave the ashes.
I have absolutely no experience with any coal fired heater/stove. I think it is probably 20 years since I have seen a piece of coal! So I am sorry, I cannot help you with this.
Well done.
Very interesting but how well does it heat the space and how large of space does it heat? Just seems like those temps aren’t very hot?
This is the problem. This particular heater is in a 14m2 room but it cannot be viewed in isolation, It is just around the corner from the baking oven, in the other direction there is the sauna stove on the other side of the wall. They all work together to heat the space. I wish it were so simple.
As someone with some experience with Finnish masonry heaters, the temperatures are really not even supposed to go very high. The point is that you only burn like at tops twice a day, and when it is not that cold maybe only three times a week. And that mass will store the heat, releasing it slower.
The original concept of using mass to store heat is literally thousands of years old and used in Saunas long before any written records of it.
Just surrounding my wood stove with 1500 lbs of concrete paver mass has made a difference for me. It really evens out the heat spikes and probably saves me a little firewood as well.
I remmember that when i grew up and we go visit grandpa then he had a house buid in 1865 from natural stones and wall thickness about 80cm - he had also this type (round and tall) he had to burn it every second dat when outside was -25C id was about 1m in diMETER nd from that gases was also going true a brick heat battery/wall wat was heated from both sides - from kithsen stove and from the "rocket" one... - they are good and efficient I heard that that was masons secret how to make them and at it was been used local stones for heat acumulation - can not confirm if the stones was used - I'm 43 now and they still going fine......
Very nice, thank you. The Pönttöuuni reminds me of the Utermark stove, which was developed in the Russian empire in the 1820s (ru.wikipedia.org/wiki/Печь_Утермарка ). I think that's where the idea of the metal sheet came from, as Finland was part of the Russian empire at the time. The Utermark stove had several up and down channels to maximise thermal efficiency by getting the last bit of heat out of the exhaust gases.
For some reason the link does not work. Probably our idiot government blocking anything Russian. I'll check out the Uttermark stove though. Thanks for the tip!
@@downdirty9642Конечно ,МЫ, следим за тобой😅.
@@downdirty9642Твоя печь на чертеже похожа на печь Грум-Гжимайло инженер теплотехник, металлург 19-20 век.
Thanks for this but it is quite difficult to find information about his stoves.
@@downdirty9642 I don't know where the idea for the metal clad ones came from, but I was under the impression that tiled ones became popular in manor houses in Sweden some time around the 1700's... Which would also explain why these types of heaters are common in both Finland and Sweden, as that would predate the period of Russian occupation (1809-1917).
What's always puzzled me about such stoves is how do to clean all the passages within it? Surely there is a need to get a brush in there to sweep them periodically?
нет не надо чистить.если печь правильно сделана и горение идет с высокой температурой то сажи не будет.
Very interesting comparison . The reason why on the left with full burn all the time surface temperature was lower may be because the speed of flue gases was too high. I am going also to build masonry heater. Do you have experience with rocket masonry heater - batchrocket with heat riser, vortex? Could be big difference between "classic" fireplace with afterburn chamber and any rocket stove? In terms of clean burning , flue temperature and total amount of heat from the same amount of wood.
I would also suspect that having the hatch fully open, you get plenty of excess air. Ideally you would want flue gas with minimal amount of remnant O2. One should keep in mind that most of the gas (both intake and exit) is N2, wich is mostly inert and does not contribute to the burn, but will transfer heat up the chimney. So any volume of excess air is effectively more than doubled.
But on the other hand, with solid fuels you typically still want some remnant O2, because before it would reach zero, you usually get unburnt fuel in the form of carbon monoxide, soot and tar.
I have done some tinkering around with a flue gas analyzer. At one point I literally spent hours and hours with a 350 kW boiler with a wood pellet stoker. It was quite interesting actually, but took a lot of waiting, as I quickly learned that when burning wood based fuels making any adjustment will take some time before the burn will reach a new equilibrium state.
14:36 so part of the secret is the sand battery..? Can you heat water and put it in the ground?
The name sounds and spells Finnish, they are popular in Sweden, I lived in a house in Sweden with five rooms and one of those in every room. Although mine where white in colour.
Adding a sand battery is genius.
You know in Spain they have a great old heating system.
Per my comment below,.... the draft is very impressive, but that's because of the extremely long riser in that giant metal tube. A "J" rocket will draft like that on a small, 3 foot (or less) riser. Please see my comment below on the website you must see.
I am confused. - Per your comment below - (can't find any comment below)
ok, found it.
Great subject. Few issues, however. Please lose the music. It is not necessary and it is cripplingly annoying.
Also you have sound problems. Most of the time I could not hear what you were saying, even at max sound settings
lol the Internet has become a catalogue of the world’s incorrect opinions raining down the OPPOSITE of information upon us all
for f sake kakelugnar has been in sweden since 1700 get you facts right and its not from russia its from italy get your facts straight from beginning from pot stoves and we in sweden did innovate the tile stove in 1700 wow so russia has nothing to do with this or findland sorry
Heads up, taking this kind of tact regardless of how annoyed you happen to be is very likely to backfire on anyone who reads it. I have no horse in this race and yet I want to tell you to f off with the attitude and I'm all for learning new facts.
I see that the "svenska avundsjukan" is alive and well...
Hell, that is boring.
YT algorithm strikes again )
Fluid dynamics and heat transfer isn't boring. We started 5000 years ago and still baffled by it.
Still don’t get it very badly illustrated 🥵🥵