Oven Stoves and Heat Walls (2008)(lowtechmagazine.com)
lowtechmagazine.com
Oven Stoves and Heat Walls (2008)
https://www.lowtechmagazine.com/2008/12/tile-stoves.html
109 comments
>The drawback of taking a long time to heat up shouldn’t be overlooked either. Anyone who has lived in a stone or brick house could tell you...
But have you ever lived in a home with a tile stove like described in the article? The time it takes to heat up isn't really an issue in my experience. Yes, it takes a bit longer than with radiators but unless you're out on holiday your house wouldn't be completely cold, would it? You get up, it's still warm from the previous night, then you throw some fresh wood in the oven and start a new fire. Especially with well insulated homes as they're built these days it works well. But here's the actual problem, apart from taking up space like you already mentioned: The fire has to be maintained. I'm pretty sure that's the main reason they've fallen out of use. It just doesn't fit into our fast paced lifestyle with small families and busy parents anymore. Back in the day there generally used to be someone home, either the housewife or the greatparents or one of the 15 children or so. Wood fired stoves just got automated out of existence like most other stuff. Central heating can be set to a certain temperature and be forgotten about. Sure, you can do that now by getting a modern gas burning tile stove, or retrofitting an old one with modern tech. But by now most have already fallen in disuse. I find it unlikely they will be revived outside of niche cases for the simple reason that fossil fuel is on it's way out. Floor heating is great and can be electric, powered by green energy.
But have you ever lived in a home with a tile stove like described in the article? The time it takes to heat up isn't really an issue in my experience. Yes, it takes a bit longer than with radiators but unless you're out on holiday your house wouldn't be completely cold, would it? You get up, it's still warm from the previous night, then you throw some fresh wood in the oven and start a new fire. Especially with well insulated homes as they're built these days it works well. But here's the actual problem, apart from taking up space like you already mentioned: The fire has to be maintained. I'm pretty sure that's the main reason they've fallen out of use. It just doesn't fit into our fast paced lifestyle with small families and busy parents anymore. Back in the day there generally used to be someone home, either the housewife or the greatparents or one of the 15 children or so. Wood fired stoves just got automated out of existence like most other stuff. Central heating can be set to a certain temperature and be forgotten about. Sure, you can do that now by getting a modern gas burning tile stove, or retrofitting an old one with modern tech. But by now most have already fallen in disuse. I find it unlikely they will be revived outside of niche cases for the simple reason that fossil fuel is on it's way out. Floor heating is great and can be electric, powered by green energy.
> But here's the actual problem, apart from taking up space like you already mentioned: The fire has to be maintained. I'm pretty sure that's the main reason they've fallen out of use.
TBF masonry heaters with modern enclosed fireplaces can slow-burn at high efficiency, and even if the fire goes out because the fireplace remains very warm and the flow is active restarting it is generally easy.
Per the few friends who have masonry heaters, if you throw a log on before going to bed, with ventilation set low, odds are high you'll still have embers in the morning and will just need to throw a new log on and stoke a bit to get it going again.
So while the convenience is a bit lower than with central heating it's hardly a back breaker. The cost of installation and structural requirements (masonry heaters weigh literal tonnes), as well as awareness of the option, are more likely.
The latter factor should not be discounted, most people don't really go out their way to look for options (if they're even doing / ordering the building in the first place, which for masonry heaters is a requirement: retrofitting a masonry heater in an existing building is very risky), so they'll get one of the options they're provided with.
TBF masonry heaters with modern enclosed fireplaces can slow-burn at high efficiency, and even if the fire goes out because the fireplace remains very warm and the flow is active restarting it is generally easy.
Per the few friends who have masonry heaters, if you throw a log on before going to bed, with ventilation set low, odds are high you'll still have embers in the morning and will just need to throw a new log on and stoke a bit to get it going again.
So while the convenience is a bit lower than with central heating it's hardly a back breaker. The cost of installation and structural requirements (masonry heaters weigh literal tonnes), as well as awareness of the option, are more likely.
The latter factor should not be discounted, most people don't really go out their way to look for options (if they're even doing / ordering the building in the first place, which for masonry heaters is a requirement: retrofitting a masonry heater in an existing building is very risky), so they'll get one of the options they're provided with.
There are two properties which are interesting: (1) the heat capacity and (2) the heat conductivity.
Yes, water has a high heat capacity, but a metal + circulating water system also has high heat conductivity[1] which means it releases the heat into the air quickly and doesn't hold heat for long. Stone releases heat more slowly since it doesn't conduct heat so well. Stone has heat capacity about 1/2 of water per unit of mass, but on the other hand the mass of stone in a oven is usually pretty high. I'd side with the author about stone being a better material for holding heat.
[1] For heat holding can probably conflate radiating with general heat conductivity here since the low conductivity results in low radiating heating due to the surface temperature of the heating element being farther from the hot core and closer to the surrounding air to be heated.
Yes, water has a high heat capacity, but a metal + circulating water system also has high heat conductivity[1] which means it releases the heat into the air quickly and doesn't hold heat for long. Stone releases heat more slowly since it doesn't conduct heat so well. Stone has heat capacity about 1/2 of water per unit of mass, but on the other hand the mass of stone in a oven is usually pretty high. I'd side with the author about stone being a better material for holding heat.
[1] For heat holding can probably conflate radiating with general heat conductivity here since the low conductivity results in low radiating heating due to the surface temperature of the heating element being farther from the hot core and closer to the surrounding air to be heated.
Yea, but low voltage pumps are pushing moving water through pipes (copper, or Pex) throughout your home when the boiler (modern condensing boiler) is on. You want a efficient release of heat.
So I agree with you that stone is a better material for holding heat, by how much--I don't know.
Having a stone fireplace might make sence heating one room, but I still have my doubts on energy saved, unless you have some kind of adobe house built around a huge stone fireplace.
It just seems more practical to have hydronic heating in your structure than a stove in each room. I have tried to heat a home with a Wolf Stove in a fireplace. A Wolf stove use just a metal stove with a fan in it. It's a fireplace insert. It only heats up the room it's in. It does heat up the bricks on the fireplace, but not enough to keep heat in when the fire is out.
If anyone decides to put in a hydronic heating system, you will like it. It's good for allergies too. I put one in a bay area home, and the install is pretty simple. The books make it much more complicated than needed.
Basically put down pex piping, or registers (radiators, baseboard) in each room. Soneyinrd you need both. Buy a boiler that has been around awhile. Condensing boilers are new, but efficient. Buy your primary pump, and your sector pumps. Know the difference between primary, and secondary piping. You will need an expansion tank. I used a mixture of copper, and pex. And a thermostat.
(In the Bay Area, we use natural gas. An electric heating here is very costly. Stay away from electric. Oh yea, for some reason hydronic heating was stopped in the 50's here. Contractors went to forced air, even though most homes don't have air conditioning. This means many hvac techs do not know how to work on hydronic, but act like they do. So double check their estimates.)
So I agree with you that stone is a better material for holding heat, by how much--I don't know.
Having a stone fireplace might make sence heating one room, but I still have my doubts on energy saved, unless you have some kind of adobe house built around a huge stone fireplace.
It just seems more practical to have hydronic heating in your structure than a stove in each room. I have tried to heat a home with a Wolf Stove in a fireplace. A Wolf stove use just a metal stove with a fan in it. It's a fireplace insert. It only heats up the room it's in. It does heat up the bricks on the fireplace, but not enough to keep heat in when the fire is out.
If anyone decides to put in a hydronic heating system, you will like it. It's good for allergies too. I put one in a bay area home, and the install is pretty simple. The books make it much more complicated than needed.
Basically put down pex piping, or registers (radiators, baseboard) in each room. Soneyinrd you need both. Buy a boiler that has been around awhile. Condensing boilers are new, but efficient. Buy your primary pump, and your sector pumps. Know the difference between primary, and secondary piping. You will need an expansion tank. I used a mixture of copper, and pex. And a thermostat.
(In the Bay Area, we use natural gas. An electric heating here is very costly. Stay away from electric. Oh yea, for some reason hydronic heating was stopped in the 50's here. Contractors went to forced air, even though most homes don't have air conditioning. This means many hvac techs do not know how to work on hydronic, but act like they do. So double check their estimates.)
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They have hydronic registers that have very dense copper/aluminum fins and are powered by fans. An extremely small unit can heat a huge area; they are by far the most space efficient system that exists. They are also very fuel efficient.
Hydronic heating is usually the best. The problem with floor systems is poor adjustability, usually noticed on cool down times, but the initial heating can also be very slow. With registers you stop flowing the water and turn off the fan. Or do the reverse and make the air hot immediately.
Hydronic heating is usually the best. The problem with floor systems is poor adjustability, usually noticed on cool down times, but the initial heating can also be very slow. With registers you stop flowing the water and turn off the fan. Or do the reverse and make the air hot immediately.
Couldn't you combine both systems relatively easily to get the best of both worlds?
Something like this: Imagine a standard central heating system: Radiators connected to a boiler through a water circuit.
Except now, the boiler's exhaust is additionally led through an oven-stove-like stone structure that acts as a "heat storage". The water piping goes through both the boiler and the stone structure.
You retain the flexibility and speed of central heating: If you want to heat up a room quickly, the boiler can heat up the water directly; if you want to cool a room down, disconnect the radiator. However, at the same time, the stone structure will store heat long-term and will hopefully allow the boiler to run for shorter periods of time.
I gotta admit, it's less exciting than an actual oven stove though, as it reduces the principle from "radically different ways of heating" to "minor technical improvement of boiler systems".
There might also be the issue that heat transfer from the stone structure happens indirectly again, which might make the system less efficient than an actual oven-stove.
Something like this: Imagine a standard central heating system: Radiators connected to a boiler through a water circuit.
Except now, the boiler's exhaust is additionally led through an oven-stove-like stone structure that acts as a "heat storage". The water piping goes through both the boiler and the stone structure.
You retain the flexibility and speed of central heating: If you want to heat up a room quickly, the boiler can heat up the water directly; if you want to cool a room down, disconnect the radiator. However, at the same time, the stone structure will store heat long-term and will hopefully allow the boiler to run for shorter periods of time.
I gotta admit, it's less exciting than an actual oven stove though, as it reduces the principle from "radically different ways of heating" to "minor technical improvement of boiler systems".
There might also be the issue that heat transfer from the stone structure happens indirectly again, which might make the system less efficient than an actual oven-stove.
There are even to this day quite a lot of houses in Russia with this exact setup. My grandparents old house had an oven stove and radiators. They replaced the oven stove with an electric boiler sometime in 2000s but kept the radiators.
Re: latency, a story... The landlords for a house I lived in once had installed some German European-style electric rads which contained a pile of ceramic bricks. They were far more efficient than regular electric baseboards for obvious reasons. The problem was they just weren't up to the job of handling a Canadian winter. Not because they couldn't keep the house warm enough but because we are prone to extreme temperature swings. From +16C to -20C in 24H is entirely conceivable and happened one winter while we were there. We froze for hours while waiting for the bricks to heat.
The conclusion I came to is that heating systems like this with huge buffering capacity make sense for western Europe where weather systems are relatively stable. But continental climates swing too quickly.
The conclusion I came to is that heating systems like this with huge buffering capacity make sense for western Europe where weather systems are relatively stable. But continental climates swing too quickly.
> They were far more efficient than regular electric baseboards for obvious reasons.
What are the reasons? They are not obvious to me.
What are the reasons? They are not obvious to me.
The big sell was holding heat made during the night during off-peak hours to be spread during the day when rates go up.
Ah, so it's at least more efficient for the wallet. Makes sense, thanks.
Why did the bricks go from 16c to cold that quickly?
That's not what I said. The outside temp dropped that way, and the heaters can't respond quick enough to ramp up the heat. The bricks take too long to heat up.
Ah, I see.
Yes, even a metal stove can be efficient…it does not have to be made of stone. The efficiency increase of a proper designed wood stove over a fireplace is due to two factors
1. Metal wood stoves slow the combustion rate down by blocking incoming air. So they can burn logs over several hours rather than all at once. Obviously the stove must be airtight.
Russian wood stoves just use a mass of masonry and have lots of internal baffles to extract the most heat. They burn a large fire at a high temperature to have increased efficiency and extract the most heat into the stone.
2. Both types of stove use high temperatures and preheated secondary air to achieve complete combustion. Open fireplaces let 50% of the energy in the wood escape as unburned gases.
1. Metal wood stoves slow the combustion rate down by blocking incoming air. So they can burn logs over several hours rather than all at once. Obviously the stove must be airtight.
Russian wood stoves just use a mass of masonry and have lots of internal baffles to extract the most heat. They burn a large fire at a high temperature to have increased efficiency and extract the most heat into the stone.
2. Both types of stove use high temperatures and preheated secondary air to achieve complete combustion. Open fireplaces let 50% of the energy in the wood escape as unburned gases.
> Russian wood stoves just use a mass of masonry and have lots of internal baffles to extract the most heat. They burn a large fire at a high temperature to have increased efficiency and extract the most heat into the stone.
Yeah these are called Masonry Heaters [1] in the West. They work by forcing the heat generated through combustion to dump as much of its energy as possible into parts of the heater that live inside the house rather than venting hot air out of a chimney. The goal of an efficient masonry heater is to make sure the exhaust gas is cold so that all the heat energy has been extracted.
> Both types of stove use high temperatures and preheated secondary air to achieve complete combustion. Open fireplaces let 50% of the energy in the wood escape as unburned gases.
The alternative here is to use a catalytic converter to start a secondary reaction and burn exhaust gasses themselves releasing even more heat and resulting in a cleaner burn and fewer harmful exhaust gasses. Modern American wood stoves can come with EPA certifications [2] indicating the use of the catalytic converter or some other technique (say, a secondary burn chamber) to reduce exhaust gasses.
[1]: https://en.wikipedia.org/wiki/Masonry_heater [2]: https://www.epa.gov/burnwise/epa-certified-wood-stoves
Yeah these are called Masonry Heaters [1] in the West. They work by forcing the heat generated through combustion to dump as much of its energy as possible into parts of the heater that live inside the house rather than venting hot air out of a chimney. The goal of an efficient masonry heater is to make sure the exhaust gas is cold so that all the heat energy has been extracted.
> Both types of stove use high temperatures and preheated secondary air to achieve complete combustion. Open fireplaces let 50% of the energy in the wood escape as unburned gases.
The alternative here is to use a catalytic converter to start a secondary reaction and burn exhaust gasses themselves releasing even more heat and resulting in a cleaner burn and fewer harmful exhaust gasses. Modern American wood stoves can come with EPA certifications [2] indicating the use of the catalytic converter or some other technique (say, a secondary burn chamber) to reduce exhaust gasses.
[1]: https://en.wikipedia.org/wiki/Masonry_heater [2]: https://www.epa.gov/burnwise/epa-certified-wood-stoves
Yes a catalytic converter would make the stove suitable for widespread use in a city. Though it seems like NASAs solution to the space pen problem…As the old saying goes … “the Russians just used a pencil.”
In this case the Russians just used a heck of a lot of bricks. It’s a solution suitable for Siberia…where You don’t want to trust the fate of your winter nights to something with a catalytic converter!
Or worse yet, a wood stove with firmware! ( Unless it’s damn simple. )
In this case the Russians just used a heck of a lot of bricks. It’s a solution suitable for Siberia…where You don’t want to trust the fate of your winter nights to something with a catalytic converter!
Or worse yet, a wood stove with firmware! ( Unless it’s damn simple. )
Masonry heaters and catalytic converters/secondary burn chambers are somewhat unrelated. The masonry heater forces the exhaust gas to keep as much of its heat inside the indoors as possible. An efficient stove produces a very efficient reaction to burn its input fuel, creating higher temperatures and cleaner exhaust gasses. The masonry heater is a solution meant for a time when folks didn't know how to cleanly/hotly burn wood. The two methods (efficient wood stove and masonry heating) can be combined for even more heating efficiency.
The problem with masonry heaters is that they require the house to be built alongside the masonry heater (e.g. you need to run the thermal mass inside the house so it can convect heat into the house). The thermal mass required can also be very expensive and/or labor intensive to make. Moreover cleaning a masonry heater and maintaining it can be a large pain depending on the size of the thermal mass.
Catalytic converters have been in widespread use for automobiles since the '70s (that's ~50 years) so they're pretty proven technology now. Secondary burn chambers are even older (early 1900s I believe.)
The problem with masonry heaters is that they require the house to be built alongside the masonry heater (e.g. you need to run the thermal mass inside the house so it can convect heat into the house). The thermal mass required can also be very expensive and/or labor intensive to make. Moreover cleaning a masonry heater and maintaining it can be a large pain depending on the size of the thermal mass.
Catalytic converters have been in widespread use for automobiles since the '70s (that's ~50 years) so they're pretty proven technology now. Secondary burn chambers are even older (early 1900s I believe.)
> The same is true of radiant floor heating in a slab. This can make your home difficult to adapt to temperature swings.
The hi-tech solution, is to have a computer control your heating, and let it take account of inside/outside temperature, presence/absence of people (per building and per room), predictions of weather/energy-cost/carbon-intensity/arrival times and so on.
Smart thermostats already do most of this e.g. learning how long it takes to get to a specific temperature with your heater, your insulation, your weather, your schedule, time-based tariffs. I'm not sure if they record this in any human readable exportable format though.
The hi-tech solution, is to have a computer control your heating, and let it take account of inside/outside temperature, presence/absence of people (per building and per room), predictions of weather/energy-cost/carbon-intensity/arrival times and so on.
Smart thermostats already do most of this e.g. learning how long it takes to get to a specific temperature with your heater, your insulation, your weather, your schedule, time-based tariffs. I'm not sure if they record this in any human readable exportable format though.
The factors are latency and assumptions of perfect future data. Their point stands; if your environment ends up 5-10 degrees warmer or cooler than expected, it takes time to course correct, even with a smarter control system.
> The drawback of taking a long time to heat up shouldn’t be overlooked either. Anyone who has lived in a stone or brick house could tell you that it will stay warm once it’s warm but bringing it up to temperature can take a long while. The same is true of radiant floor heating in a slab. This can make your home difficult to adapt to temperature swings.
Too true. I call it "Thermal inertia".
The problem with heating up a wall and hoping it releases the heat back into your home is that the wall tends to radiate heat on both sides (internal and external), while you are only heating it from one side (internal). In effect, you are literally wasting half the heat you attempted to store into the wall.
With the type of houses I've lived in (concrete/brick + plaster) the external cladding (plaster) does nothing to insulate the bricks/blocks from the outside. If you want to retain more of the heat you "stored" in the walls (to be released internally) you need to put on a thermally insulated cladding.
Too true. I call it "Thermal inertia".
The problem with heating up a wall and hoping it releases the heat back into your home is that the wall tends to radiate heat on both sides (internal and external), while you are only heating it from one side (internal). In effect, you are literally wasting half the heat you attempted to store into the wall.
With the type of houses I've lived in (concrete/brick + plaster) the external cladding (plaster) does nothing to insulate the bricks/blocks from the outside. If you want to retain more of the heat you "stored" in the walls (to be released internally) you need to put on a thermally insulated cladding.
When talking about wall heating, it's typically an interior wall that's used (and a solid stone one at that - no breeze block and plaster here). Exterior walls are obviously suboptimal.
As someone who suffers through winter smog caused by people in my county heating their homes with wood, please please please use a modern efficient heating source instead of this neopasotral quackery.
I live in a very rural area where wood burning for heat makes a lot of sense. We have vastly too much deadwood on the ground and it is a serious fire hazard. There is simply no other economic way to dispose of it than to burn it. Most of it gets burned in vast piles by the county and forest services. From my lot, I divert a few cords per year of that to my woodstove. Either way it is going up in smoke. This way, for an acceptable amount of labor, I heat my house and save about $1,500 a year in propane charges.
This is less healthful for me than propane in terms of indoor air pollution. But it is more healthful in terms of exercise and fire prevention. I've accepted that compromise with the help of an air purifier that stays on all winter. Also, when I can get all of my fuel within a few hundred yards of my front door, most of the extraction and transportation costs go away.
And there's something else that's very important to me: When I burn propane, I micromanage the thermostat to save money. I wear heavier clothes all winter and end up tolerating being more cold and uncomfortable. With wood fuel being so much more economical, and surfing the edge of comfort less practical, I just keep the woodstove going all day and cool the house at mid day by opening some windows ... getting fresh air that I just don't get when using propane. So the house is mostly warmer all day than with propane, and I'm wearing less and generally more comfortable.
It's a pretty easy choice for me. I'd like to keep it up as long as I'm physically able.
This is less healthful for me than propane in terms of indoor air pollution. But it is more healthful in terms of exercise and fire prevention. I've accepted that compromise with the help of an air purifier that stays on all winter. Also, when I can get all of my fuel within a few hundred yards of my front door, most of the extraction and transportation costs go away.
And there's something else that's very important to me: When I burn propane, I micromanage the thermostat to save money. I wear heavier clothes all winter and end up tolerating being more cold and uncomfortable. With wood fuel being so much more economical, and surfing the edge of comfort less practical, I just keep the woodstove going all day and cool the house at mid day by opening some windows ... getting fresh air that I just don't get when using propane. So the house is mostly warmer all day than with propane, and I'm wearing less and generally more comfortable.
It's a pretty easy choice for me. I'd like to keep it up as long as I'm physically able.
He’s not saying that wood heat isn’t practical or rational for you, he’s saying that the byproduct of smoke and particulate matter imposed as a negative externality on your neighbors is not fair.
I live in a semi rural heavily forested area where wood heat is an option. I definitely notice the drop in air quality when winter comes around. Part of the problem is that for whatever reason wood smoke from stoves tends to hang out at ground level and cover the area rather than rising away. I don’t get any benefit from wood heat, but I do suffer the costs…
I live in a semi rural heavily forested area where wood heat is an option. I definitely notice the drop in air quality when winter comes around. Part of the problem is that for whatever reason wood smoke from stoves tends to hang out at ground level and cover the area rather than rising away. I don’t get any benefit from wood heat, but I do suffer the costs…
I wonder if all that excess heat from burning can be captured and stored somehow.
It can, but it requires building around heated seating in a building. You have an intake, a horizontal inlet pipe, a firebox, and then a 90° into a chimney inside of a dome, made of thick clay. You then use a horizontal outlet to the dome near the floor, with a rectangular cross section a ratio to the interior chimney size, ideally, and you build concrete or clay benches, bedframes, etc around your room, with these rectangular exhausts in the middle.
The fire gets going very hot, burns off all of the stuff that comes out of wood, on purpose, to turn into heat, which heats the masonry, which will stay warm for a very long time. The dome also radiates heat for a very long time. The final outlet, out of the house, expels tepid, wet, clean air; contains only CO2 as a byproduct, iirc.
The fire gets going very hot, burns off all of the stuff that comes out of wood, on purpose, to turn into heat, which heats the masonry, which will stay warm for a very long time. The dome also radiates heat for a very long time. The final outlet, out of the house, expels tepid, wet, clean air; contains only CO2 as a byproduct, iirc.
For others reading along, just lookup rocket mass heater. You'll find plenty of pictures and YouTube videos.
My question was specifically about burning of deadwood for forest management, which apparently is available in huge quantities that need to be disposed of, but perhaps not consistently enough to e.g. use it to heat a city hall or gymnasium.
Wood pellets might be an answer. Some houses use pellet burning furnaces as an alternative to gas fuelled boilers etc. It is niche though.
There seemed to be a small wave of pellet furnace installations in Germany 5-10 years ago or so. From what I heard, pellets became so expensive in the meantime that new installations declined. Long story short: there is demand for wood pellets. The price is about 300€/(metric) ton right now.
Drax[0] in the UK have outfitted their old coal plants with wood pellets which are apparently sourced from the US. Questionable how much value there is in it given the carbon footprint of the shipping and the unclear stewardship of some of the wood.
[0]: https://www.drax.com/
[0]: https://www.drax.com/
I also heat water with my stove. 2 hot water tanks, the first tank is unpowered has cold city water coming into it and is ran through a coil on my wood stove and then cycles back into the tank with a hot water pump. The second tank is powered and draws from the first tank. So cold city water is heated prior to going to my second tank it saves me lots of power each year.
I'm from Northern Ontario, and I agree that wood smoke can be killer, especially below -30°C (-22°F) when the smoke stays near the ground. Oven stoves, according to the article, address this. The section "Complete combustion", is all about this issue:
> Wood can be burned without too much air pollution, but then the temperature has to be high enough: 1100 to 1200 degrees Celsius. In that case, 99 percent of the wood is converted to CO2 and water vapour, almost without smoke. A metal wood stove, however, only reaches a temperature of 650 to 700 degrees, with an incomplete wood combustion as a result.
> Wood can be burned without too much air pollution, but then the temperature has to be high enough: 1100 to 1200 degrees Celsius. In that case, 99 percent of the wood is converted to CO2 and water vapour, almost without smoke. A metal wood stove, however, only reaches a temperature of 650 to 700 degrees, with an incomplete wood combustion as a result.
Are these significantly different in mechanism from so-called "rocket mass stoves"? I remember reading about those a few years ago. Seems like they burn very "clean" and require relatively little fuel to heat a home.
Rocket stoves are efficient when they're small, you have to have a secondary gassification byproduct burn chamber. I can't remember what the whole heat system is called, but it involves a lot of cob and clay.
> 99 percent of the wood is converted to CO2 and water vapour, almost without smoke
CO2 is a critical problem.
CO2 is a critical problem.
Biofuels like wood can be roughly carbon-neutral, since growing them absorbs atmospheric CO2, and burning them releases that same amount of carbon back into the atmosphere.
Though obviously this isn't the case if the wood comes from badly-managed forests that are not replanted. And there are other effects that can make wood fuel carbon-positive:
https://www.smithsonianmag.com/smart-news/epa-declares-burni...
Though obviously this isn't the case if the wood comes from badly-managed forests that are not replanted. And there are other effects that can make wood fuel carbon-positive:
https://www.smithsonianmag.com/smart-news/epa-declares-burni...
True, but it doesn't matter. After you burn the wood, you are adding carbon that doesn't need to be there. The physics don't distinguish between carbon that is produced by a short carbon cycle or a long one.
In the case of wood, the carbon is accessed from, and ultimately returned to, the active biosphere. It's not fossil fuel that's been sequestered for 100s of millions of years, but was itself captured largely within recent decades.
Contrasted with burning coal, oil, or gas, preferred.
(Woodfuel may still be burned unsustainably, that's a separate question.)
Noted FWIW in TFA:
[U]nlike gas and oil, wood is a renewable and CO2-neutral fuel (the CO2 that is produced by the burning of wood was taken out of the atmosphere by the tree during the years before). The problem is that wood stoves are not very efficient, and extremely polluting.
Contrasted with burning coal, oil, or gas, preferred.
(Woodfuel may still be burned unsustainably, that's a separate question.)
Noted FWIW in TFA:
[U]nlike gas and oil, wood is a renewable and CO2-neutral fuel (the CO2 that is produced by the burning of wood was taken out of the atmosphere by the tree during the years before). The problem is that wood stoves are not very efficient, and extremely polluting.
Whilst it is for burning fossile files, when you’re burning the wood that grew on your property over the past 20 years, the carbon cycle is much shorter. Especially if your property grows it all back, it’s a closed carbon loop.
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Modern heating is not nearly as cheap as wood heat, at least around me. The problem is not wood burning as much as it is burning unseasoned wood. There should be strict regulations for firewood sellers ensuring wood is seasoned properly but what happens is every year some guy with a truck cuts a bunch of wood and sells it with very little seasoning. This creates the smoke you are experiencing. I can heat my home for about 2 months for $300 where any other heat would cost significantly more. Not just heat my house but heat it to the point I can walk around in my underwear. I've never been able to afford to do that with any other type of heat. Furthermore I have 2 hot water tanks. The first one is connected to the second and city water enters the first tank and the first tank is not powered. It does run to my fireplace through copper pipe and a copper coil at the stove. So for the price I pay for wood I get excess heat and hot water. No other heat can come close.
Purely out of curiosity (I've never permanently lived somewhere where woodburning stoves were essential for home heating): is this because people are over-burning wood to compensate for the slow warming-up time, or because the stoves themselves are inefficient, or something else?
When I was young (~10 years old), we installed a wood-burning stove in the family-room of our house. My dad had a lot of family and friends who were farmers and were in constant need for tree removal.
Our heating costs dropped so significantly that the Gas company called, concerned that we weren't running our Natural Gas fired furnace and that we might need financial assistance.
We heated this way for many years after he died. I took up the responsibility of cutting down trees, splitting wood; and keeping the house warm. It is A LOT of work, but worth it if you have access to the trees/woodlots.
In the future (if this housing crisis ever ends), I will be adding a Rocket Mass Heater to my home. There is nothing in the world that compares to the feel of a roaring fire on a cold winter. One year the power went out in a very large geographic region that affected a large portion of the population. No electricity meant that no furnaces were running; so we had some elderly neighbors and family move in with us. They could have easily died without our wood-stove running. We even used it to cook on!
Our heating costs dropped so significantly that the Gas company called, concerned that we weren't running our Natural Gas fired furnace and that we might need financial assistance.
We heated this way for many years after he died. I took up the responsibility of cutting down trees, splitting wood; and keeping the house warm. It is A LOT of work, but worth it if you have access to the trees/woodlots.
In the future (if this housing crisis ever ends), I will be adding a Rocket Mass Heater to my home. There is nothing in the world that compares to the feel of a roaring fire on a cold winter. One year the power went out in a very large geographic region that affected a large portion of the population. No electricity meant that no furnaces were running; so we had some elderly neighbors and family move in with us. They could have easily died without our wood-stove running. We even used it to cook on!
It's very cool that you will be adding a rocket mass heater. They fascinate me endlessly (I've posted about them here before) and are what led me to read about masonry heaters. It's unfortunate that RMHs are so difficult to insure, but I hope that building one is in my future as well.
The stoves just put off a lot of particulate pollution. Stoves don't completely combust the wood or do so at the wrong temperature which results in much more pollution than burning an equivalent energy amount gas.
That certainly makes sense; I've only ever used fireplaces and you can visibly see the particulate those emit.
I'm guessing it's outside of the economic envelope in which people are burning wood anyways, but the article makes it sound like combusting at the "right" temperature essentially solves that problem. But I suppose at that point you might as well just burn something cleaner and retain the other advantageous parts of the design.
I'm guessing it's outside of the economic envelope in which people are burning wood anyways, but the article makes it sound like combusting at the "right" temperature essentially solves that problem. But I suppose at that point you might as well just burn something cleaner and retain the other advantageous parts of the design.
Look up rocket stoves, and rocket mass heaters. Properly built, they effectively produce only co2 and steam, even all carbon monoxide is consumed.
Of course, since each rmh is custom built, you need to actually test the exhaust of every one to ensure it works as intended.
Mine is pretty swell, albeit a tad annoying to keep going if we leave for a few days and the whole mass cools. With that said, it uses about 1/10th the wood of a new high efficiency wood stove we use in a different building.
Of course, since each rmh is custom built, you need to actually test the exhaust of every one to ensure it works as intended.
Mine is pretty swell, albeit a tad annoying to keep going if we leave for a few days and the whole mass cools. With that said, it uses about 1/10th the wood of a new high efficiency wood stove we use in a different building.
For anyone looking to compare masonry heaters with rocket mass heaters, this is a nice introduction: https://www.lowtechmagazine.com/2015/03/radiant-and-conducti...
RMHs are very interesting to me, but unfortunately due to their niche status, they're currently very hard to get insured.
(PS. I would love to see a picture of your RMH, is possible!)
RMHs are very interesting to me, but unfortunately due to their niche status, they're currently very hard to get insured.
(PS. I would love to see a picture of your RMH, is possible!)
Not mine, but what I based mine on:
https://youtu.be/8ptwncPImuo
Reading that article, I am curious as to why they say that rmh are less efficient than tile stoves. The exhaust temp on mine is around 130-150 degrees F- cooler than a fresh cup of coffee. And yet, I get pretty complete combustion- so all of the heat from the wood is captured inside my house.
I recently saw a claim that rmh can produce less CO2 for the same heat than gas furnaces, though that was just someone on the internet, I would definitely want more research to claim that.
https://youtu.be/8ptwncPImuo
Reading that article, I am curious as to why they say that rmh are less efficient than tile stoves. The exhaust temp on mine is around 130-150 degrees F- cooler than a fresh cup of coffee. And yet, I get pretty complete combustion- so all of the heat from the wood is captured inside my house.
I recently saw a claim that rmh can produce less CO2 for the same heat than gas furnaces, though that was just someone on the internet, I would definitely want more research to claim that.
You'd be surprised how common it is, the largest source of air pollution in the winter in the SF bay area is from people burning wood.
What are the other major sources of air pollution / particulate pollution in the Bay Area?
There's no coal consumption to speak of. There's diesel fuel consumption, though that is largely concentrated on transport corridors (I-80, I-580, US-101).
Wildfire emissions all but certainly swamp woodstove usage.
That said, yes, a small number of poorly-tuned fireplaces can create a large amount of smoke. Where the intent is actual useful heating, and not fireplace-as-decoration, thats' a solvable problem.
There's no coal consumption to speak of. There's diesel fuel consumption, though that is largely concentrated on transport corridors (I-80, I-580, US-101).
Wildfire emissions all but certainly swamp woodstove usage.
That said, yes, a small number of poorly-tuned fireplaces can create a large amount of smoke. Where the intent is actual useful heating, and not fireplace-as-decoration, thats' a solvable problem.
See here for the other sources: https://www.baaqmd.gov/~/media/files/communications-and-outr...
Look on page 7
39% Wood Smoke 12 Cooking 12 Other Mobile Sources 12 Road Dust 7 On-Road Motor Vehicles 6 Combustion: Stationary Sources 5 Industrial/Commercial Processes 3 Construction and Farming Dust 2 Animal Waste 1 Wind-Blown Dust 1 Wildfires
Wildfires are basically non-existent in the winter, although the Colorado fire currently doesn't bode well for future California winters.
Look on page 7
39% Wood Smoke 12 Cooking 12 Other Mobile Sources 12 Road Dust 7 On-Road Motor Vehicles 6 Combustion: Stationary Sources 5 Industrial/Commercial Processes 3 Construction and Farming Dust 2 Animal Waste 1 Wind-Blown Dust 1 Wildfires
Wildfires are basically non-existent in the winter, although the Colorado fire currently doesn't bode well for future California winters.
That is indeed very surprising!
My understanding is that here in NYC the single largest (non-industrial?) source of air pollution is heating oil. The city banned the two worst heating oils back in 2015, but with a long phase-out period[1]. I would have expected the situation to be the same in most other cities, although SF's weather certainly doesn't justify oil burning the way NYC's does :-)
[1]: https://www.ny-engineers.com/blog/how-nyc-is-phasing-out-hea...
My understanding is that here in NYC the single largest (non-industrial?) source of air pollution is heating oil. The city banned the two worst heating oils back in 2015, but with a long phase-out period[1]. I would have expected the situation to be the same in most other cities, although SF's weather certainly doesn't justify oil burning the way NYC's does :-)
[1]: https://www.ny-engineers.com/blog/how-nyc-is-phasing-out-hea...
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I'm not sure how much heating oil use there is in California, seemed like most people without natural gas use either wood or propane.
Less that its so common, more that a small percent of people cause all of that pollution. They usually convince themselves they are being environmentally friendly because "I just use the wood I already have from my land!!" And the rest of us suffer their refusal to use a modern heating source.
*recreationally
I think heat pumps are far more likely to be a 'savior' in terms of energy efficiency and climate issues than going back to burning wood en masse, which the end of this article handwaves away even though it seems pretty obvious that it isn't really sustainable.
Manually operated wood furnaces are also terrible with regards to particle emissions. The article acknowledges that and claims that oven stoves do not have this problem because they can reach higher temperatures. But that ignores the fact that there is a time period until the fire has reached the right temperature during which the particle emissions are very high (particle emissions from wood furnaces are scary high and dwarf emissions from cars). If the whole neighborhood is heated by these things, then you have several hours of the day with smoke and particles, even if everyone operates their ovens correctly so they reach the correct temperatures for a clean burn.
Furthermore, heat pumps are just so much more efficient, as they actually move several times the amount of energy as heat as they consume as electricity. Combined with floor heating - which gives a much larger surface area for heat dissipation than these oven stoves can ever give you - you can further lower the temperature of the water, raising efficiency even more. Floor heating is also way more comfortable as it gives an even distribution of heat throughout the house, and you don't get cold feet.
Furthermore, heat pumps are just so much more efficient, as they actually move several times the amount of energy as heat as they consume as electricity. Combined with floor heating - which gives a much larger surface area for heat dissipation than these oven stoves can ever give you - you can further lower the temperature of the water, raising efficiency even more. Floor heating is also way more comfortable as it gives an even distribution of heat throughout the house, and you don't get cold feet.
Silly question, but if a heat pump extracts warmth out of the ground, how much extraction can take place before that warmth runs out?
Quantitatively, of course planet Earth has infinite warmth to give compared to what we could possibly extract but I have no idea what the numbers are actually like.
Quantitatively, of course planet Earth has infinite warmth to give compared to what we could possibly extract but I have no idea what the numbers are actually like.
Not a silly question at all. Firstly, heat pumps do not need to extract heat from the ground, they can also extract it from the air or a body of water. The heat moved from outside to inside a building will always leak out eventually, returning to the environment. In the case of air heat pumps this means there is very little change of local air temperature over any time scale.
You are right that extracting too much heat from the ground will make the ground around the exchanger too cold, which will make the process less efficient and have negative environmental effects, which means it is illegal in many places. Smaller systems like for homes are usually very shallow and will regain enough heat from the air and sun over the course of the year. Larger systems can be problematic. The common solution to this is to use the ground as a thermal battery (or install a thermal battery in the ground, using it for insulation). Then you can use your heat pump to extract heat in the cold season and in the warm season you can cool the building and move that heat back underground. This has the extra benefit of being even more efficient, since you are basically just trading heat and cold from season to season.
You are right that extracting too much heat from the ground will make the ground around the exchanger too cold, which will make the process less efficient and have negative environmental effects, which means it is illegal in many places. Smaller systems like for homes are usually very shallow and will regain enough heat from the air and sun over the course of the year. Larger systems can be problematic. The common solution to this is to use the ground as a thermal battery (or install a thermal battery in the ground, using it for insulation). Then you can use your heat pump to extract heat in the cold season and in the warm season you can cool the building and move that heat back underground. This has the extra benefit of being even more efficient, since you are basically just trading heat and cold from season to season.
I think this is a really good way to put it into perspective, because the units we use for temperature are very misleading on this front:
Where I live, the outside temperature goes from -40C to +40C at the extremes (though those are rare and the 'normal maxes' are more like -30 to +30). In F that's -40 to +104F.
But in kelvin, which actually measures the amount of energy in the air, that's 233K to 313K. It's not a small difference in the amount of energy, but neither number is anywhere close to zero.
It's a common meme with heat pumps that they "stop working under X temp" because it's too cold, but the actual, immediately practical issue is moisture. Ice is a great insulator, so when the outside part of your heat pump is covered with ice it no longer works well. Presumably the same might be true of ground source heat pumps and frost, though I know less about that. Obviously there are other factors like the efficiency and operating range of the coolant used and such, but you hit this moisture barrier before those.
There are ways around that (I installed an air source heat pump this year and it runs in reverse (ie. as an air conditioner) periodically to defrost the outside part. I've used it successfully to heat my home down to about -20 outside before it no longer spends any real time in heating mode. It wasn't cheap though, and is almost certainly not cost-effective even over a very long time period. That's not my priority though.
Where I live, the outside temperature goes from -40C to +40C at the extremes (though those are rare and the 'normal maxes' are more like -30 to +30). In F that's -40 to +104F.
But in kelvin, which actually measures the amount of energy in the air, that's 233K to 313K. It's not a small difference in the amount of energy, but neither number is anywhere close to zero.
It's a common meme with heat pumps that they "stop working under X temp" because it's too cold, but the actual, immediately practical issue is moisture. Ice is a great insulator, so when the outside part of your heat pump is covered with ice it no longer works well. Presumably the same might be true of ground source heat pumps and frost, though I know less about that. Obviously there are other factors like the efficiency and operating range of the coolant used and such, but you hit this moisture barrier before those.
There are ways around that (I installed an air source heat pump this year and it runs in reverse (ie. as an air conditioner) periodically to defrost the outside part. I've used it successfully to heat my home down to about -20 outside before it no longer spends any real time in heating mode. It wasn't cheap though, and is almost certainly not cost-effective even over a very long time period. That's not my priority though.
> Presumably the same might be true of ground source heat pumps and frost, though I know less about that.
I looked into this, since I'm getting an air-to-water heat pump installed next month, and considered a ground heat pump. Ground heat pumps require a large area of pipes, roughly 3x the area of the house. Less than that, and I was told that I'd risk creating permafrost around the pipes, greatly reducing the efficiency of the pump.
Regarding cost, my heat pump will replace a gas heater, and should actually cut my yearly expenses to almost 1/3. If that is actually how things are going to work out (and assuming the electricity price surges in Europe are temporary) then it'll pay itself back in 8-10 years. Granted, I live in Denmark where most of the price of gas and electricity is environment taxes, and those are cut for the electricity that is spent by a heat pump, thus making it more cost effective than if those taxes weren't there.
I looked into this, since I'm getting an air-to-water heat pump installed next month, and considered a ground heat pump. Ground heat pumps require a large area of pipes, roughly 3x the area of the house. Less than that, and I was told that I'd risk creating permafrost around the pipes, greatly reducing the efficiency of the pump.
Regarding cost, my heat pump will replace a gas heater, and should actually cut my yearly expenses to almost 1/3. If that is actually how things are going to work out (and assuming the electricity price surges in Europe are temporary) then it'll pay itself back in 8-10 years. Granted, I live in Denmark where most of the price of gas and electricity is environment taxes, and those are cut for the electricity that is spent by a heat pump, thus making it more cost effective than if those taxes weren't there.
Most of the cost for me was really a "no one here does it yet tax" on the unit itself, along with an "everything is much more expensive in canada tax" tbh. If I were in the US the unit would have been half the cost and it'd probably be cost effective on a reasonable timeline, esp. if carbon taxes increase over the next ten years as currently scheduled.
Right now though the cost to heat my house with gas and the cost to heat it with the heat pump at the marginal temperatures is about the same. I still have an operational and relatively new gas water heater though or I'd be looking into turning off the gas for 2/3 of the year and that would save a lot of money since there's a lot of fixed costs on my bill for even having gas at all.
Right now though the cost to heat my house with gas and the cost to heat it with the heat pump at the marginal temperatures is about the same. I still have an operational and relatively new gas water heater though or I'd be looking into turning off the gas for 2/3 of the year and that would save a lot of money since there's a lot of fixed costs on my bill for even having gas at all.
Ground source heat pumps with shallow heat collection coils extract heat stored by the sun during the previous warm season.
With deeper boreholes you're extracting heat from radioactivity decay.
In both cases the rate at which you can extract that heat depends in the heat transfer rate in the ground around the coils/boreholes.
With deeper boreholes you're extracting heat from radioactivity decay.
In both cases the rate at which you can extract that heat depends in the heat transfer rate in the ground around the coils/boreholes.
I don't know if this is right. We're talking about thermodynamic heaters, like Peltier elements, correct? Those need electricity to work and the question then becomes: where does the electricity come from? Burning wood, if it can be done efficiently, and like the article says, is almost neutral in terms of carbon emissions because you're only realeasing carbon that is part of the atmospheric carbon cycle, circulating between the atmosphere and the biosphere.
With a heat pump, if the electricity comes from burning fossil fuel then you're contributing to greenhouse gas emissions (all those carbon gasses are released in a much higher rate than they were stored and, more importantly, than what the environment can keep up with). If the electricity comes from renewable sources, then it's a real saving, but how probable is that right now? If you can burn wood at 80-90% efficiency, as the article claims, then that's a net gain right now.
Personally I also don't like the reliance on a complicated mechanism that can't be easily made by hand. I don't like that because it means the technology is harder to adopt. I'm talking about heat pumps. By the sound of it an "oven stove" is much easier to make and maintain, if they had them back in the middle ages. So they can be used by many more people for whom the price of electricity is higher than the price of scrap wood. For a technology to make a difference it doesn't just need to be efficient, it must also be affordable and useable by everyone.
With a heat pump, if the electricity comes from burning fossil fuel then you're contributing to greenhouse gas emissions (all those carbon gasses are released in a much higher rate than they were stored and, more importantly, than what the environment can keep up with). If the electricity comes from renewable sources, then it's a real saving, but how probable is that right now? If you can burn wood at 80-90% efficiency, as the article claims, then that's a net gain right now.
Personally I also don't like the reliance on a complicated mechanism that can't be easily made by hand. I don't like that because it means the technology is harder to adopt. I'm talking about heat pumps. By the sound of it an "oven stove" is much easier to make and maintain, if they had them back in the middle ages. So they can be used by many more people for whom the price of electricity is higher than the price of scrap wood. For a technology to make a difference it doesn't just need to be efficient, it must also be affordable and useable by everyone.
"Heat pump" typically refers to a refrigeration cycle unit that uses a working fluid to transfer heat from a cold body to a hot body. An air conditioner uses this mechanism to heat the outside of the home (cooling the inside).
Technically electricity is not required, although most of these units, in practice, use electricity, converted to mechanical energy, to power compressors.
Heat pumps are much more efficient than e.g. electric baseboard heating because the energy consumed is used to move heat, rather than to generate heat. The efficiency difference drops in "very" cold climates (ambient temperatures well below freezing) and in those climates the heat pump usually is backed up by a direct heating method such as resistance electric heating, gas furnace, et cetera.
Technically electricity is not required, although most of these units, in practice, use electricity, converted to mechanical energy, to power compressors.
Heat pumps are much more efficient than e.g. electric baseboard heating because the energy consumed is used to move heat, rather than to generate heat. The efficiency difference drops in "very" cold climates (ambient temperatures well below freezing) and in those climates the heat pump usually is backed up by a direct heating method such as resistance electric heating, gas furnace, et cetera.
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As sibling reply said, while peltier elements are technically heat pumps they're not the kind that's used in home heating.
There are two things that make them much more efficient in terms of GHG than other kinds of heating:
- Using central electricity generation means using more efficient combustion. Where I live most heating is done by gas and it is extremely inefficient compared to even a gas power plant. This is why we use central electricity generation to begin with; everyone running their own generator would be extremely bad for the environment. Even if it was 1:1 generated energy input to heat it would still be better for the environment for me to be using that generated electricity than directly buring gas in my home. Also as you allude to but dismiss, much of the electricity cost can be offset by using solar or wind directly at site, and it's likely that eventually most central generation will switch off GHG emitters and if/when it does you will automatically go with it.
- Heat pumps with a refrigerant cycle don't use 1:1 energy input to heat produced. They're moving energy, not producing it as burning, resistive, or even thermoelectric do. So long as conditions are right, heat pumps only use a fraction of the energy they bring into your home. So the efficiency gains are compounding here.
At any rate, it's simply not feasible to convert all heating to wood burning, even if it is efficient. As the article points out the last time this was done they basically caused intense deforestation and likely there were climate effects from that. The idea that now, with several billion more people on the planet, we can do it again but get it right this time is absurd. We will never be able to plant trees on the scale necessary to do this, never mind the transportation costs (in terms of both environmental and monetary) of shipping a bunch of wood around to homes all over the place to keep them heated.
At any rate, we're likely to start needing tech like heat pumps a lot more as climate change accelerates. There are parts of the planet that are likely to become basically unliveable without AC soon, and as the heat dome last year showed even 'cold' areas are likely to start experiencing heat levels they're unable to really manage (up here in the north we build homes to hold heat in. Guess what that's like in a heat dome).
There are two things that make them much more efficient in terms of GHG than other kinds of heating:
- Using central electricity generation means using more efficient combustion. Where I live most heating is done by gas and it is extremely inefficient compared to even a gas power plant. This is why we use central electricity generation to begin with; everyone running their own generator would be extremely bad for the environment. Even if it was 1:1 generated energy input to heat it would still be better for the environment for me to be using that generated electricity than directly buring gas in my home. Also as you allude to but dismiss, much of the electricity cost can be offset by using solar or wind directly at site, and it's likely that eventually most central generation will switch off GHG emitters and if/when it does you will automatically go with it.
- Heat pumps with a refrigerant cycle don't use 1:1 energy input to heat produced. They're moving energy, not producing it as burning, resistive, or even thermoelectric do. So long as conditions are right, heat pumps only use a fraction of the energy they bring into your home. So the efficiency gains are compounding here.
At any rate, it's simply not feasible to convert all heating to wood burning, even if it is efficient. As the article points out the last time this was done they basically caused intense deforestation and likely there were climate effects from that. The idea that now, with several billion more people on the planet, we can do it again but get it right this time is absurd. We will never be able to plant trees on the scale necessary to do this, never mind the transportation costs (in terms of both environmental and monetary) of shipping a bunch of wood around to homes all over the place to keep them heated.
At any rate, we're likely to start needing tech like heat pumps a lot more as climate change accelerates. There are parts of the planet that are likely to become basically unliveable without AC soon, and as the heat dome last year showed even 'cold' areas are likely to start experiencing heat levels they're unable to really manage (up here in the north we build homes to hold heat in. Guess what that's like in a heat dome).
To go to the opposite direction from the low tech starting point: You could have both a micro-chp setup to genetate both heat and electricity from the fuel, leaving the option to use the electricity on a heat pump or other household demands.
And heat pumps can be fit into existing systems.
Yeah but this “system” has advantages heat pumps don’t have.
Such as the lack of a convective air circulation system.
Such as the lack of a convective air circulation system.
Something to keep in mind though:
https://www.theguardian.com/environment/2021/dec/17/wood-bur...
"Wood burning stoves in urban areas are responsible for almost half of people’s exposure to cancer-causing chemicals found in air pollution particles, new research has shown."
This is less of a concern with modern batch-rocket stoves that also burn fine particles, once hot, after a few minutes, they burn without smoke.
Unless the wood is moist. Or the logs are too large. Or the wood is of the wrong kind or of bad quality. Or the stove is used incorrectly (ID10T error).
Exactly. The average user has to be very cautious. I wonder how cautious they are having paid good money for a fully compliant stove install and then think their job is over.
Are these user-originated problems detectable using the right combination of sensors ?
If they paid attention they'd notice it smokes. There's usually a small window in the oven for that purpose, our eyes and noses a good enough sensors for that.
Old rural houses where I'm from were basically a huge kitchen/dinning room build around this kind of a stove + the rest of the house. The oven heats water in pipes going through the masonry and they heat the rest of the house through radiators. And then you also use that water for bathing.
So you cook in the evening so that you have hot water for bathing before going to sleep and the house is warm through the night.
It also has warm shelves near the ceiling used for drying clothes/shoes/fruits/mushrooms.
Very efficient, but it means the whole house is build around it.
So you cook in the evening so that you have hot water for bathing before going to sleep and the house is warm through the night.
It also has warm shelves near the ceiling used for drying clothes/shoes/fruits/mushrooms.
Very efficient, but it means the whole house is build around it.
This sounds awesome.
Article:
> The energetic output of an oven stove is 80 to 90 percent, compared to 40 to 50 percent for metal stoves or central heating appliances
Energy.gov
> Old furnaces: 56% to 70%
> Mid efficiency furnaces: 80% to 83%
> High efficiency furnaces: 90% to 98.5%
https://www.energy.gov/energysaver/furnaces-and-boilers
EDIT: We can cut the article some slack as ducting (as typically done) does account for losses which are highly variable.
> The energetic output of an oven stove is 80 to 90 percent, compared to 40 to 50 percent for metal stoves or central heating appliances
Energy.gov
> Old furnaces: 56% to 70%
> Mid efficiency furnaces: 80% to 83%
> High efficiency furnaces: 90% to 98.5%
https://www.energy.gov/energysaver/furnaces-and-boilers
EDIT: We can cut the article some slack as ducting (as typically done) does account for losses which are highly variable.
Well, what does "energetic output" mean? If I understand the core point of the article correctly, radiant heat only heats the surface of objects not the air, so it will require less heat for the same effect. I don't how to put a number on this.
I think the energy.gov article you mentioned primarily talks about heat leaking outside:
> An AFUE of 90% means that 90% of the energy in the fuel becomes heat for the home and the other 10% escapes up the chimney and elsewhere.
I think the energy.gov article you mentioned primarily talks about heat leaking outside:
> An AFUE of 90% means that 90% of the energy in the fuel becomes heat for the home and the other 10% escapes up the chimney and elsewhere.
this article lost me when I saw those numbers. It also treats heat like some kind of magic and not based on thermodynamics. heat is heat, no matter how quickly or slowly it spreads. A big thermal mass will hold heat, but will also take longer to heat in the first place. You're spending the same number of BTUs in the long run.
I don't know how the Kimberly [1] fits into the essay. It has two combustion cycles to burn clean and more efficiently. It's relatively expensive compared to most wood stoves. Originally designed for heating a boat, thus compact.
[1] https://www.unforgettablefirellc.com/kimberly-wood-stove/
[1] https://www.unforgettablefirellc.com/kimberly-wood-stove/
That seems awesome!
The rocket mass heater is the modern replacement for this.
https://www.youtube.com/watch?v=fwCz8Ris79g
Uses about 1/10th the fuel, and fuel can be wood unusable in other stoves.
Very little exhaust / smoke.
Super efficient.
https://www.youtube.com/watch?v=fwCz8Ris79g
Uses about 1/10th the fuel, and fuel can be wood unusable in other stoves.
Very little exhaust / smoke.
Super efficient.
I live in center of historical city in middle of Europe. All houses are from 15th to 19th century and most od them has chimneys. In our house there are two oven stoves and we use it during winter. We are able to keep 21°C in entire house even during -10°C outside. With rising prices of gas, it is incredibly handy and saves money. House has old wood windows, not ideal for keep constant temperature inside and yet, it works great.
These work very well. That's why I'm a little surprised none of the youtube build your own cottage videos people every try putting one of these in, and always do the metal stove. WhichI don't believe will keep you warm all night, without having to get up and add more wood.
I've experienced radiant floor heating powered by a wood stove, on my trip to Europe, it was very nice. Not sure how it worked.
I've experienced radiant floor heating powered by a wood stove, on my trip to Europe, it was very nice. Not sure how it worked.
Strange sentence there: "In a room that is heated by an oven stove, a thermometer can hardly measure anything." Saying that as someone heating my house twice per day by wood brick oven and having multiple thermometers to measure the ambient air in the rooms warming.
What I wondered about these brick stoves is how do they clean them properly? Surely they need to be cleaned of build up periodically as a woodstove needs to be done annually to prevent chimney fires.
If they burn hot enough there should be almost no volatiles left. Most chimney buildup is from fires/chimney being too cold, improperly seasoned wood, or burning the wrong types of wood/not mixing those poor burning woods with other woods.
Ash buildup could still be a problem, but would take years to build up enough to be a problem, although it likely would still need to be cleaned out at some point, although a vacuum with a proper filter could be an option or have access points built in for that eventuality.
Ash buildup could still be a problem, but would take years to build up enough to be a problem, although it likely would still need to be cleaned out at some point, although a vacuum with a proper filter could be an option or have access points built in for that eventuality.
I’ve burnt for years and absolutely build ultra hot fires occasionally to get ride of creosote build up but eventually like you say will get ash build up which can burn or eventually just plug the pipe. You would need access points to use a vacuum because the article showed these things zig zag back and forth to make the heat travel around the bricks. Maybe it just takes years and years since the article claims you only need to burn for a couple hours a day where my wood stove burns all day.
I suspect, though I have no documentation, that they are generally built with "cleanout" access points along the exhaust path (possibly in the form of "these are the stones to chisel out if the thing needs cleaning; be sure to mortar them back into place when you are done!")
There are modern takes on this idea, with highly efficient (85%) burning cores that also burn the fine particles traditionally present in wood fire smoke, resulting in a smoke-less combustion.
Plugging https://www.uzume.fr (site in French) an engineer and indie stove maker that makes neat products starting at €4000 for a stove kit that you build yourself.
Plugging https://www.uzume.fr (site in French) an engineer and indie stove maker that makes neat products starting at €4000 for a stove kit that you build yourself.
That brings me the good memories from the east Germany times, when we all spent our nights around such heaters. They were great, but I assume that would be impossible to have such things today when people want to dictate how we all should produce CO2.
In France, https://www.uzume.fr/ is releasing open source plans for self building « batchblock » a mix between a rocket stove and a mass heater.
I'm still waiting on the oven/fireplace with a water pipe for exhaust fumes. We could filter it through water like a bong right? In that case you could burn newspapers, advertisment material all in your home.
> Today’s energy crisis is not the first in human history.
The article is from 2008, I wonder what the author refers to here. Possibly using more environmentally sustainable energy sources? Or using less energy in general?
The article is from 2008, I wonder what the author refers to here. Possibly using more environmentally sustainable energy sources? Or using less energy in general?
Just as a tiny nitpick: the German word "Kachelofen" does not translate to "oven stove", but to "tile oven" - a term mentioned at the beginning of the same paragraph.
I think these are neat and the idea of running a stove for only a short time each day would be great, but the architectural drawbacks should be obvious. The heart of your house is now lost to a massive stone structure.
The drawback of taking a long time to heat up shouldn’t be overlooked either. Anyone who has lived in a stone or brick house could tell you that it will stay warm once it’s warm but bringing it up to temperature can take a long while. The same is true of radiant floor heating in a slab. This can make your home difficult to adapt to temperature swings.