5 ms·

These are cool but when talking of alternative heating systems the author misunderstands how hydronic heating (radiators) work and blames metal for being a poor

These are cool but when talking of alternative heating systems the author misunderstands how hydronic heating (radiators) work and blames metal for being a poor material for holding heat and as heating the air through convection. This is all incorrect, the heat transfer medium is the water which is great at retaining heat, and the heaters heat primarily through radiation (although they do use convection over fins to speed the rate at which they heat the room.) Another form of hydronic heat would be radiant heat in your floor which would be very close to having a oven stove under your feet. 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.

R0b0t1 5y ago
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.
hasmanean 5y ago
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.
- Karrot_Kream 5y ago
  > 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 https://en.wikipedia.org/wiki/Masonry_heater [2]: https://www.epa.gov/burnwise/epa-certified-wood-stoves https://www.epa.gov/burnwise/epa-certified-wood-stoves
  - hasmanean 5y ago
    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. )
    - Karrot_Kream 5y ago
      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.)
lelanthran 5y ago
> 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.
- swiftcoder 5y ago
  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.
trompetenaccoun 5y ago
>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.
- masklinn 5y ago
  > 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.
fulafel 5y ago
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.
- hellbannedguy 5y ago
  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.)
xg15 5y ago
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.
- nzmsv 5y ago
  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.
ZeroGravitas 5y ago
> 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.
- NBJack 5y ago
  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.
cmrdporcupine 5y ago
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.
- throwaway55421 5y ago
  Why did the bricks go from 16c to cold that quickly?
  - cmrdporcupine 5y ago
    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.
    - throwaway55421 5y ago
      Ah, I see.
- balfirevic 5y ago
  > They were far more efficient than regular electric baseboards for obvious reasons. What are the reasons? They are not obvious to me.
  - cmrdporcupine 5y ago
    The big sell was holding heat made during the night during off-peak hours to be spread during the day when rates go up.

R0b0t1 5y ago

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.

hasmanean 5y ago

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.

Karrot_Kream 5y ago
> 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 https://en.wikipedia.org/wiki/Masonry_heater [2]: https://www.epa.gov/burnwise/epa-certified-wood-stoves https://www.epa.gov/burnwise/epa-certified-wood-stoves
- hasmanean 5y ago
  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. )
  - Karrot_Kream 5y ago
    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.)

lelanthran 5y ago

> 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.

swiftcoder 5y ago
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.

trompetenaccoun 5y ago

>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.

masklinn 5y ago
> 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.

fulafel 5y ago

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.

hellbannedguy 5y ago
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.)

xg15 5y ago

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.

nzmsv 5y ago
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.

ZeroGravitas 5y ago

> 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.

NBJack 5y ago
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.

cmrdporcupine 5y ago

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.

throwaway55421 5y ago
Why did the bricks go from 16c to cold that quickly?
- cmrdporcupine 5y ago
  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.
  - throwaway55421 5y ago
    Ah, I see.
balfirevic 5y ago
> They were far more efficient than regular electric baseboards for obvious reasons. What are the reasons? They are not obvious to me.
- cmrdporcupine 5y ago
  The big sell was holding heat made during the night during off-peak hours to be spread during the day when rates go up.