Stone or Steel!

[johnstra]

I'm curious how many of you with a stone stove would switch to steel or are you devoted to stone. Myself, if I had it to do over again, would probably choose steel. I was afraid that a steel stove would cook us out of the room (and it just might), but I find that on cold (below zero) nights, I'd love to have the radiant heat of steel. I'm not 100% convinced of this, though, because I do appreciate the even heating of stone - that's a legitimate benefit. I think if I switched to steel I'd want a catalyst in order to even out the burn.

Don't get me wrong... I really like my Mansfield. It puts out a lot of heat and it's very easy to control the burn on large and small loads. It pretty much heats my 2000+ sq ft house with very high ceilings all by itself to 70+*. It does struggle on sub-zero nights (the furnace kicks in to help) and if you ever let it go cold it takes a long time to get it up to temp again. If I could get it up to 750 when I need the heat it would be perfect.

 

[Todd]

I'm pretty much stuck on stone but the way they make these steel stoves now a days with the extra steel or cast jacket surround it really cuts back on the radiant heat and feels somewhat like a stone stove.

 

[BrotherBart]

I run a big steel stove naked of jackets half in and half out of a fireplace and get some of the storage benefit from the bricks and the radiant off the front half. But I have always wanted to burn in a Mansfield just to see how it does.

I just flat love the look of that big rock. Duck feet and all. But it was too tall to fit in that hole.

I think the talk about the radiant "blast" is highly over blown with the insulated fireboxes in EPA stoves. I have always had a thermo on the side of the 30-NC and it stays pretty steady at 500-550 even when I had the blast off burn this year that went up to toward 900 stove top. Both verified with my IR thermo.

 

[johnstra]

Interesting... you're both saying there may not be a huge difference in radiant heat between stone and modern steel stoves. I had a 2005 vintage VC Encore in a different house. That stove felt like it poured a lot more heat off it than the Mansfield, but it was in a much smaller house with 8' ceilings. Maybe I need to get a job testing wood stoves... then I could satisfy my curiosity

 

[BrotherBart]

Interesting... you're both saying there may not be a huge difference in radiant heat between stone and modern steel stoves. I had a 2005 vintage VC Encore in a different house. That stove felt like it poured a lot more heat off it than the Mansfield, but it was in a much smaller house with 8' ceilings. Maybe I need to get a job testing wood stoves... then I could satisfy my curiosity

Or just send me the Mansfield and I will do a comparison. :cheese: I had my 30-NC shipped here from Boulder. The freight ain't too bad.

 

[snowleopard]

I've lived with a variety of wood stoves in the past: barrel stoves, a steel stove, cast iron, a wood cook stove, and the stone beats them all hands down. No regrets, no second thoughts. I've got a nice-sized piece of glass in front that I can sit in front of when I want that warm-me-to-the-bones sensation, and I get all the heat off of it that I can stand. However, I had a pipe damper put in when I had the stove installed, and that really helps with the cook-me-out-of-here sensations when I want that extra heat.

I've never had it reach 600 on the stovetop, but it will heat the hearthroom to 80 if I want, and has kept my 2000sf house very comfortable at -30F, with no secondary heat source---but this house is designed for a cold climate, with 8' ceilings and plenty of insulation.

The rock stays

ETA: On second thought, that little wood cookstove was a strong contender, and I'd love to have one of those again. In addition to the Hearthstone.

 

[ddddddden]

Y'know, in a thread I was reading recently(don't know if it was a recent thread or one I dredged up), a guy who seemed like he knew his stuff was saying that a stove transitions from convection to more radiation as it gets hotter. . .so I'm wondering if some of the s0ft heat mojo is that the stone soaks up more heat, which, aside from the neato heat storage and spike buffering trick, maybe makes the stove run cooler than it would if it were made of metal, so it tends to convect more than radiate. . .? Haven't had the rock north of 600* either, AFAIK,. . .been wondering how I was gonna do that when the day for it comes(not often in this clime). . .hot reloads, I guess. . .or some of that magic wood that Dennis uses to hit 700. Get rid of the rock? Nah, it heats the house, and it brings a sensual vibe to the room that it did not have before with the steel insert. . .nothing to do with heating, but part of the equation.

 

[Milton Findley]

I would not go back to a cast iron stove, but I would like to find a way to wake my stove up a little faster from a cold start. Not that this makes any difference at all in the greater scheme of things. My rock stove went out last night at about 8 PM. It was on a low level burn all day, just a split here and there. It is 38 degrees outside, on a windy day, and it is still 70 degrees in here.

I have never managed to fire my stove to even 500 degrees, it seems to level out at about 425, and requires a lot of small splits to get hotter than that. My chimney is a foot over the minimum length, and I think that draft is what is limiting the burn rate. Even so, the light show is very impressive.

It radiates enough to heat the several tons of rock wall behind it to over a hundred degrees on a regular basis.

 

[Martin Strand III]

Stone vs steel?
Radiant vs convection?
Stove won't heat everything on very cold nights?

Let's clear some things up.

Stone vs steel?
Ideally in a heating system for most 'normal' situations, we want high burning efficiency (not to waste BTUs) and MODERATE heat transfer of that heat to the room. Metal (steel, cast iron) has HIGH heat transfer properties which make metal wood stoves less than ideal for heat transfer to the room - it's too much heat too fast causing wide swings in thermal cycling, hot-cold-hot-etc, aka indoor weather. Adding stone to metal stoves softens this a bit and for all but extremes in cold works pretty well. Brutal cold responds better to brutal (HIGH) heat transfer; i.e., LARGE all metal stoves - small or undersized all metal stoves don't cut it in a severe cold snap. All stone (masonry) heaters seem to have the best solution for both high burn efficiency and moderate heat transfer and work better (release stored BTUs slowly to the room over time) than their metal or metal/stone cousins due to their THERMAL MASS (7500+ lbs vs 400 - 600 lbs).

Radiant vs convection?
Physics tells us a warm surface at a lower temperature (165* F) emits RADIANT energy of LOWER AMPLITUDE than that of a hot surface (450* F). The effect of this, with time, is the lower surface temperature material warms objects and not the air (like rays from the sun on a cool spring day). The hotter the surface temperature, the higher the amplitude of the radiant energy which then strikes more molecules of air causing more CONVECTION heat (more indoor weather). The truth is most all stoves emit both radiant heat energy and cause convection heat as well.

Stove won't heat everything on very cold nights?
This is a common misunderstanding because a basic principle is misunderstood: wood stoves are LOCAL AREA heaters. Simply, you can't get a bus load of people in a VW beetle. If you happen to have a large wood stove, you may be able to heat your entire house for most heating days. Congratulations, you seem to have nullified the basic principle. But no. In extremes of ambient temperature, a wood stove will not make you happy. Very cold outside - it won't heat the whole house. Very warm outside - even a small stove with a small fire is too much.

The devil is in the details.

Aye,
Marty

 

[shawneyboy]

For me, I would want nothing else other than the big rock. I have used both steel inserts and steel stoves, as well as my Mansfield. I would never change to a non-rock stove. The storage capacity of heat of the stove is awsome. On these type of warm, but still chilly days, I can run a cycle or 2 of smaller more or less kindling and get the stove top up to 450-500. Then let it keep the house warm, both up and downstairs, all day.

On the cold days, fill her up and she heats the entire house. Stove top cruises along 525 - 550 and if you want that blast of heat, sit near that window, holy molly !

I am amazed when someone like Milt says they can not get it above 425. All setups are different, I agree but I have never had a problem to get up to temp. I usually cruise along on the brutal cold days at 525-550. During shoulder season and when the heat need is less, simply lessen the size of the fill up, or as said run it a cycle and let her go.

Milt I am wondering if you could describe your setup either PM or in a seperate thread (don't wanna hijack), I understand you have the minimum length essentially but I would like to know more about your setup to see if I could give you some limited help in getting it up to a higher temp, (of course, only if this is what you want).

To repeate and to answer the OP question, now that I have a big rock, I would never go back. I am a stoner for life.

Shawn

 

[johnstra]

How about some more of you Woodstock owners? I know you're a loyal lot.

Doesn the Woodstock have a double-layer of stone instead of single?

Marty - Given good convective airflow through the house, my impression is that a sufficiently sized heater should be able to do a decent job heating more than just the stove room. My house has a very open floorplan with the second floor landing over my stove room. I don't have to get far away from my stove on a cold night before it becomes very chilly. My kitchen is about 25' away from the stove with no walls in between. If I go into the kitchen on one of these cold nights it's pretty darn cold and floors are flat-out freezing.

 

[Martin Strand III]

How about some more of you Woodstock owners? I know you're a loyal lot.

Doesn the Woodstock have a double-layer of stone instead of single?

Marty - Given good convective airflow through the house, my impression is that a sufficiently sized heater should be able to do a decent job heating more than just the stove room. My house has a very open floorplan with the second floor landing over my stove room. I don't have to get far away from my stove on a cold night before it becomes very chilly. My kitchen is about 25' away from the stove with no walls in between. If I go into the kitchen on one of these cold nights it's pretty darn cold and floors are flat-out freezing.

Your "very chilly", "pretty darn cold" and "flat-out freezing" comments, despite your open floor plan support the basic principle that wood stoves are basically local area heaters. And, moving warmed air around (convection) is not the best way to heat a house.

We think because homes have furnaces and HVAC (a convection system), this is the standard, the best. It's not. Heating with warm air molecules flying around simply is not efficient heating despite the popularity of HVAC systems and convection ovens for cooking. It's an "even" way to heat but not efficient. Radiant heat and conduction heat beat convention heat every time.

Read more green stuff. Why do you think passive solar heating, solar panels and radiant floor heating systems are becoming more and more popular? Could we actually have learned something and are we becoming smarter?

Aye,
Marty
Grandma used to say, "Work smarter, not harder."

 

[begreen]

This is a rare time when I have to disagree with Marty. Convection does not mean forced air. Our convection stove does an excellent job of heating the house, by convection. A strongly radiant stove would be overpowering in our small livingroom and would require too much space for clearances.

All convection means is heat transfer in a gas or liquid by the circulation of currents from one region to another. For example, baseboard hot water heating works mostly by natural convection, not radiation. It's a pretty efficient form of heat and quite popular in Europe. They used to call them radiators because they were often steam driven and produced a lot of radiant heat too due to the high temp of steam. But even the old style radiators work by both radiation and convection. That's why they have so many fins. As for solar, ask precaud how his convective solar heaters are working. Quite well I think.

http://www.ehow.com/how-does_4964845_house-radiator-work.html

 

[Dakotas Dad]

I have experience with cast, steel and stone, inserts and stand alone, and even some time spent with a few diesel Yukon stoves thrown in. I have to say, I love the stone stoves for both the aesthetics and the feel of the heat.

I will stick with stone.

 

[Battenkiller]

Radiant vs convection?

Physics tells us a warm surface at a lower temperature (165* F) emits RADIANT energy of LOWER AMPLITUDE than that of a hot surface (450* F). The effect of this, with time, is the lower surface temperature material warms objects and not the air (like rays from the sun on a cool spring day). The hotter the surface temperature, the higher the amplitude of the radiant energy which then strikes more molecules of air causing more CONVECTION heat (more indoor weather). The truth is most all stoves emit both radiant heat energy and cause convection heat as well.

Actually, just the opposite is true. Above 200ºF, the higher the temperature, the more heat is emitted as IR and the less natural convection occurs.

Amplitude in EM is a measure of the intensity of the field, not the wave "height". EM waves are not the same as matter waves (i.e. water, sound), and have no physical measurement (except in wavelength and frequency). Convection occurs because air molecules come into contact with the hot surface and become hotter through conduction from the hot material itself, not because radiant heat strikes the air molecules. In fact, air is fairly transparent to IR radiation, and so is a poor absorber of heat from that source.

For most radiant stoves operating at temps from 400º to 600º, about 30-35% of the heat is transferred via natural convection. At the lower temp range of masonry heaters (about 100ºF), 35% of heat transfer occurs happens through convection. These are not theoretical figures, they are experimentally derived measurements.

 

[Battenkiller]

All convection means is heat transfer in a gas or liquid by the circulation of currents from one region to another.

Yes, but that fluid has to get hot somehow. Using blowers or even convection jackets increases the amount of air that gets heated by the hot surfaces of the stove, which is not the most effective way to warm yourself. Because of the way that human heat sensors detect heat loss, the average person can tolerate air temperatures that are about 4ºF lower if purely radiant heating devices are used instead of convection heaters which heat the air itself. Plus, moving air currents increase the evaporative cooling rate of the skin, a problem that is exacerbated by the lower winter RH in the home. You feel cooler because of that reason as well.

 

[Backwoods Savage]

We've had steel stove, cast stoves and now a soapstone. Of all we've had plus others we've been around, I'll stick to the soapstone.

As for the stone stoves heating so much slower, I do not find that to be a problem at all. It very well might be if it were in a cabin that had no heat and then you wen there during the winter. It then would no doubt be very noticeable in the time difference on heating up the cabin. But here at home, it may take just a little longer but not that much. We get good heat in a very short time. Once again, fuel is the key. If I want some heat rather quickly from a cold stove, I'll burn soft maple that is very dry. That lights quickly and burns hot. Yes, we could heat up the stove even faster but do take a little longer just because of the possibility of moisture in the stone. But all this talk about hours to get heat is nonsense.

So, although we've had experience with many stoves, we still like our soapstone. I'm not sure how the comparison between the different stoves might be but also don't want to start some dumb contests to say one is so much superior to the other. Our experience is with the Woodstock stove and it is tops in my book.

 

[thinkxingu]

Agreed, Dennis--it takes maybe 15 minutes longer for my Homestead to reach the same temp as my NC-13 and the latter is much smaller than the former. I think the difference between steel and stone is the exponential relationship between stove temperature and heating time/maintenance. My Homestead puts out exponentially higher amounts of heat when going from 300 to 400 to 500 degrees. So, my steel stove being able to run at >600* will definitely heat a room more quickly. Of course, it's definitely more localized than the gentle release of stone.

Finally, as Dennis mentioned, there is a clear difference between heating up a cold house and bringing the temp. of that same house up. When trying to warm EVERYTHING, e.g. couches, walls, ceilings, etc. takes much more heat than the latter.

S

 

[begreen]

All convection means is heat transfer in a gas or liquid by the circulation of currents from one region to another.

Yes, but that fluid has to get hot somehow. Using blowers or even convection jackets increases the amount of air that gets heated by the hot surfaces of the stove, which is not the most effective way to warm yourself. Because of the way that human heat sensors detect heat loss, the average person can tolerate air temperatures that are about 4ºF lower if purely radiant heating devices are used instead of convection heaters which heat the air itself. Plus, moving air currents increase the evaporative cooling rate of the skin, a problem that is exacerbated by the lower winter RH in the home. You feel cooler because of that reason as well.

Theory is fine, but I feel warm in the 72°F kitchen, about 30 ft away from the stove and around the corner. Is radiation bouncing off the windows? How much radiation is coming up from basement installations? Not everyone can hover around the stove just to feel warm.

We've had both a radiant stove (the F400) and a convective stove (T6) in the same location. Without a doubt, for our house and floorplan, I prefer a convective stove here. We still get radiant heat from the front of the stove, but the convective heat seems to work better at providing us with a steady even heat throughout rooms away from the stove. The radiant heat was more cyclical, hot or cool. The convective heat is more even. I also notice the inside thermometers hold the temp within a degree all day long now.

 

[pen]

I am tearing apart a ruined stone stove right now. From what I am finding, I don't think I'll ever own a stone stove for fear of needing to rebuild it some day.

For the cost, I can buy 3 of my steel stoves to 1 equivalent stone stove.

pen

 

[Martin Strand III]

This is a rare time when I have to disagree with Marty. Convection does not mean forced air. Our convection stove does an excellent job of heating the house, by convection. A strongly radiant stove would be overpowering in our small livingroom and would require too much space for clearances.

All convection means is heat transfer in a gas or liquid by the circulation of currents from one region to another. For example, baseboard hot water heating works mostly by natural convection, not radiation. It's a pretty efficient form of heat and quite popular in Europe. They used to call them radiators because they were often steam driven and produced a lot of radiant heat too due to the high temp of steam. But even the old style radiators work by both radiation and convection. That's why they have so many fins. As for solar, ask precaud how his convective solar heaters are working. Quite well I think.

http://www.ehow.com/how-does_4964845_house-radiator-work.html

Yes, but...

It's not adding up.

Your convection stove does an excellent job of heating your house, but
* it also heats by radiation energy, since, as stated, most stoves heat both ways
* you may have a small house since you have a small living room
* your particular stove/house is an individual case perhaps not representative of 'most' (?)

A strongly radiant stove would overpower and require too much space...
* my strong radiant heater (masonry) puts out gentle heat (low amplitude radiant energy) with a surface temp of 165* F
* my strong radiant heater requires only 2" clearance

"Baseboard hot water heating works mostly by natural convection, not radiation."
* But in your reference article, it says "A radiator also continues to radiate heat for some time" (This is not heating by convection)
* The water in a hot water baseboard heating system is heated by CONDUCTION which also heats the metallic fins (This is not heating by convection)

I never said "Convection does not mean forced air."

See what I mean?

Aye,
Marty

 

[Martin Strand III]

Radiant vs convection?

Physics tells us a warm surface at a lower temperature (165* F) emits RADIANT energy of LOWER AMPLITUDE than that of a hot surface (450* F). The effect of this, with time, is the lower surface temperature material warms objects and not the air (like rays from the sun on a cool spring day). The hotter the surface temperature, the higher the amplitude of the radiant energy which then strikes more molecules of air causing more CONVECTION heat (more indoor weather). The truth is most all stoves emit both radiant heat energy and cause convection heat as well.

Actually, just the opposite is true. Above 200ºF, the higher the temperature, the more heat is emitted as IR and the less natural convection occurs.

Amplitude in EM is a measure of the intensity of the field, not the wave "height". EM waves are not the same as matter waves (i.e. water, sound), and have no physical measurement (except in wavelength and frequency). Convection occurs because air molecules come into contact with the hot surface and become hotter through conduction from the hot material itself, not because radiant heat strikes the air molecules. In fact, air is fairly transparent to IR radiation, and so is a poor absorber of heat from that source.

For most radiant stoves operating at temps from 400º to 600º, about 30-35% of the heat is transferred via natural convection. At the lower temp range of masonry heaters (about 100ºF), 35% of heat transfer occurs happens through convection. These are not theoretical figures, they are experimentally derived measurements.

Please, don't take my word for it.

On Photon Wave Amplitude, and other:

"Because the particles in solids and liquids are relatively closely packed together they are very good at absorbing any radiant heat photons that happen to strike them. On the other hand gases, such as the air we breath, have enormous amounts of empty space between particles. As a result, the chance of photons hitting a gas particle is much smaller. The distance that a photon can travel through gas before striking a molecule is dependent on the amplitude of its wave motion. This amplitude will be greater (higher) in radiation from a hot object than in a cooler object. The greater the amplitude, the longer the path a photon "particle" will follow in order to cover a given distance through the gas and the greater the probability of encountering a gas molecule along that path.

Convective heat is an indirect form of heat transfer. The heat is not transferred directly, but rather indirectly through the medium of the air in the room which acts as the means of transport. The continual movement of air in a room heated by convection from a hot metal stove or a forced air system results in uncomfortable drafty conditions and uneven temperature zones. By contrast, in a room heated with a radiant heat the air remains still, eliminating uncomfortable drafts, with air temperature staying comfortably even. (my style change)"

Aye,
Marty

 

[Battenkiller]

Theory is fine, but I feel warm in the 72°F kitchen, about 30 ft away from the stove and around the corner. Is radiation bouncing off the windows? How much radiation is coming up from basement installations? Not everyone can hover around the stove just to feel warm.

No theory here, I don't know why you keep saying that when I bring up facts. It is a fact that people are evaporatively cooled by moving air, and that this effect is stronger the drier the air is, and that this difference can be measured by many different types of thermometers. It has also been definitely demonstrated that human heat sensors don't work by sensing the temperature, but rather by sensing the direction of heat flow. If heat flows out of your body faster than in flows (or is produced within), you will feel the difference, but it is not directly related to the actual air temperature itself, only the rate of heat flow and its direction. There is absolutely nothing theoretical about that, and calling it so is just a cheap way (no offense meant) to attempt to discredit sound scientific fact.

But to answer your questions...

- Yes, to a large degree, IR does reflect off the surfaces in the room. Beyond a 30º incident angle, all EM radiation increasingly reflects off of surfaces to varying degrees, depending on the absorptivity/emissivity of the surface. In can either be reflected or absorbed, not much else can happen to it.

- A lot of radiation comes from the floor in basement installations.

- With masonry chimneys, a lot gets retained by the chimney materials themselves (up to 30% in some cases), and that is radiated into the upstairs living spaces at about the same rate as a masonry heater (the walls surrounding my chimney usually measure from 85-100ºF while the stove is actively running).

- As I mentioned above, the heat sensors in your skin sense the magnitude and direction of heat flow. Put your hand up to a cold window and you can feel the cold just pouring off it, right? Wrong. Cold doesn't flow anywhere. What you are feeling is the differential rate of heat loss between two radiating surfaces. If you are radiating more heat that the opposing surface, more heat is flowing out than in and you will perceive it as being cold. In fact, both surfaces are warm in absolute terms, both are giving off radiant heat, but the colder the opposing surface is, the more heat will flow in that direction and it will feel cold, even without actually touching it.

Now let's warm all of the objects in the room with 2/3 radiant heat and about 1/3 convective heat. The closer those surfaces are to your own surface temperature (about 85Fº), the warmer you will feel in the room. The walls 6' away from my stove hit 120º at times. The floor below the stove has hit 200º, the cinder block wall behind the stove varies from about 100-140º. Once all that mass in the room gets that hot, even a 76º air temp down there feels downright uncomfortable. Next morning, the mass in that area has cooled off to some degree, so even when I get the stove up to 800º, it doesn't feel as hot in the room as when the entire mass of the room has been elevated to its previous temperatures.... even at identical air temps. I have checked this thoroughly and simultaneously with both my IR and the temperature probe that came with it. At least hat's not theory at all, just good old fashioned sensory input, the same kind of info you are citing in your own situation and drawing your own conclusions from.

 

[johnstra]

I am tearing apart a ruined stone stove right now. From what I am finding, I don't think I'll ever own a stone stove for fear of needing to rebuild it some day.

For the cost, I can buy 3 of my steel stoves to 1 equivalent stone stove.

pen

Pen - Can you elaborate? Why do the stoves need rebuilding? Abuse? Leaks? I've heard that over time stone stoves will begin to leak as the cemented joints break down.

 

[Milton Findley]

@Marty,

Thanks for the offer and my bad habits are all listed and in your in box.