Affordable way to add mass to existing woodstove?

We have a very efficient Country "Striker" woodstove heating out 1,000sqft home. Depending on how cold it is outside (and what type of wood we're burning), it puts out waaaaay too much heat at once and then it gets cold too quickly. To keep a fire burning in the "efficient zone" (like 375-650 on out woodstove), I either have to make a fire in the morning, let it die, and then make a second one later in the evening, or keep it burning and make our living room like 80 or 90 degrees by evening. I'd love to add some mass to it to even out the temperature swings, and make it even more efficient.

Here's our woodstove:




As you can see, we found some granite and soapstone slab that my parents had left over. We put them on the cooktop of the woodstove. We cook on our woodstove pretty much everyday when the fire is going, and so we need a lot of surface available, thus the soapstone is kind of piled in one corner. We also use the various levels of soapstone to warm cups of cider or thaw frozen vegetables, etc. They do a good job of getting warm and staying warm, but there's just not that much of them!

You'll also notice the pile of bricks to the side of the woodstove. That was our attempt to add more mass. We'd found the bricks on craigslist, but they're really lightweight bricks, and uneaven, so they don't really touch the side of the woodstove. The bricks closest to the woodstove are warm, but not hot, and it takes hours for them to get that way. The bricks further from the woodstove are cool, and the ones at the bottom are cold. (I just went and touched them, and the fire has been going for about 4 hours). Those that get warm, don't stay warm for very long, either.

So, these bricks seem to be a big fail. How can I improve on these bricks to add more mass, without being really expensive or breaking our manufactured home's floor?

Here's some of my ideas, but I'd really appreciate some more ideas and feedback!

(1) Remove the bricks touching the woodstove and replace them with soapstone bricks. By leaving the old bricks on the bottom, I'd be able to get the soapstone next to the woodstove where it can capture the most heat, without having to spend the money to make a tower of all soapstone. Cons: soapstone is expensive, and the tower would look funny having two different colored bricks, and the soapstone might be hard to get flush with the woodstove.

(2) Get some hardware cloth or slightly larger fencing and make square or half-moon shaped tower. Place it next to the woodstove and fill with gravel &/or granite/soapstone ends and pieces from a landscaping company. Cons: It might be really hard to bend it into shape to make it flush with the woodstove and not look bumpy. It'd be hard to clean. It might be too heavy for our floor. Pro's: probably a whole lot cheaper than buying soapstone bricks...

The gravel/rock tower would look something like this, but solid rock, and not spiral shaped and no plants, lol!



I honestly have no idea how well either of these would work for conducting/storing heat. I just know my current brick set up doesn't work.

Thank you for any and all help!

I think you might be over=thinking it a bit, but I have also built quite a few rock walls and really that is all that is needed.I looked for a picture of my old set up, that is, a wood stove with rock around it so that had thermal mass. It made a notable difference in my home, but it was a considerable amount of rock too. I would say about a cubic yard, or about 1-1/2 tons. Anything less then that and the mass really is not there to give you the better heat cycling that you need.

In my case I live on a concrete slab on grade so weight was never an issue, but on a typical frame house it might be. A few posts in the basement or crawl space propping up the framing above would be a quick, cheap answer.

To get what you are after, you really just want to stack the non-mortored rock around the stove, but preferably leaving a gap. In that way the radiant heat from the stove collides with the stone and heats it up. The more of a full wrap you can get around it, the more rock you can add, and the greater the mass will be. Naturally you want to stack the rock so that it is at least the height of the top of the stove.

In our case it worked really well and we noticed a big difference.

Make a stone chimney maybe
What are your walls made of ? We took off the plaster and got back to stone made a big difference
David

Your place looks nice, that seems to be one if your concerns,so stacked stone or a gabion baskets might be too messy for you.
I've seen water recommended as a thermal mass.
A couple of large stainless steel stock pots setting on a pedestals of brick could work ,and might look ok.
If you are commited, building forms and casting concrete around and above the stove might work.
Concrete blocks dry stacked and filled with soil might work,and be more easily reversed.
Anyway you might use to put a non combustible "shelf" over your cooking area would give a area to put mass that's right above all that rising heat.

I'm not an expert on this type of heating, but I think that I see your problem.  I would expect the system shown in the picture to fail.  When you are building a mass heater, you want as much surface to surface contact as possible from the heat source to your mass.  


You know those holes in the bricks?  Those are air pockets, because air is the best insulator.  Any air between the brick and your stove will make it much more difficult to heat the brick.  You're essentially heating the air, which circulates because it's heated, so you're stuck heating the entire room again.

If I was to build a mass heat exchange for my woodstove, I would either mortar the bricks around the stove, or use natural cob.  There's no reason that it won't work.  Bricks around an oven is a technique that has been proven by time.  On the mythbusters, they built a furnace with a toaster oven surrounded by bricks.  Those bricks had direct contact with the tabletop toaster oven, and allowed it to heat up to a higher temperature than the stock unit.  

If you want affordable ways to add mass, I would look at craigslist.  There are often many ads that ask for old chimney bricks or patio bricks to be taken away for free, or little money per truckload.  

There's one last suggestion that I have.  I would focus on putting some mass below the stove for several reasons.  I see having a stove such as yours, as having several problems.  The first is that it's elevated.  Cooler air will congregate under it, and be warmed.  Again, heating the air here will use heat that you desire to be heating your mass with.  Energy is neither created nor destroyed.  With the air below the stove being the coldest because it's lower, I would theorize that adding brick mass below the stove would be the most efficient first step in improving your stove.  You want to cob right up to the stove, creating air pockets between the bricks that then insulate and hold heat. Since that air won't flow around the room, it becomes heat retention rather than heat degrading air.  

Some people use thermofelt to wrap around their charcoal or propane grills outside. This is a very effective insulation layer, but it works exactly opposite of what you're trying to accomplish.  You don't want to hold the heat inside of the stove, but to radiate it as much as possible in close proximity.

ETA:  I would try to use soapstone as the layer directly against the stove, since it allows much more heat transfer than the bricks.  Then, I would put the less radiating bricks further on the outside.  

Greetings.  

Struggled with the same issue for quite a while in a house about the same size as yours.  Luckily, my house is mostly one big room, using bookshelves to create a bit of a bedroom area and the stove is in the middle of the house so getting the heat to circulate around isn't too difficult.  My stove was made by the brother of a friend so isn't a high efficiency burner like yours.  I think you are on the right track with your stones.  You just need more of them.  

I gave up most of the cooking on the top to trap heat with fire bricks and water.  There is a 6.5 x 9" space behind the water pot that only has a stack of 3 firebricks on it and they are easily removed to cook an egg or heat some water for tea.  Once heated, water or dinner, etc. will stay warm sitting on top of the firebricks once they are warm.   The 5 gallon pot of water gets really hot and stays warm for bathing and dish washing type chores as well as retaining heat.  I was amazed by how much this set up evened up the house heating and kept it warm for a long time.  I seldom add wood over night unless we are in the 20 belows or so range, and the bricks and water will still be warming the house in the morning.  [photo of my setup attached - i think]  My experience with just the firebricks on top has really made me crave a RMH.

I once tried adding a stack of bricks to the back of the stove to try and retain some of that heat, but it wasn't nearly as helpful/beneficial as just putting them on top - just couldn't get them close enough to heat up well.  Have thought about cobbing around the sides and back and the chimney, but I really want to put in a rocket stove with a little bench and don't want to have to clean all of that out to build the RMH.  No doubt there are ways to make it more attractive than my setup and if you can figure it out, it might be worth trading the occasional cooking on top for heat retention.  

Good luck!

I have a similar wood stove and like the idea with the gravel rock tower. HOw did you construct it? It probably has way less mass than something solid but it seems to be easy enough to make.

Angelika Maier wrote:
I have a similar wood stove and like the idea with the gravel rock tower. HOw did you construct it? It probably has way less mass than something solid but it seems to be easy enough to make.  

I haven't constructed a gravel tower. I've just seen pictures of them when people make their herb spirals. Let's see if I can find a how to...

Searching on line, I think it's called a "gabion wall." (EDIT: just noticed that William used the word gabion, so that does seem to be the right term!) Here's some pictures of one herb spiral in progress. Oh how I hate pinterst because it almost always leads me to pictures without their actual webpages!



Ah, here's an instructable on how to make a gabion wall. http://www.instructables.com/id/Cheap-DIY-Gabion-Baskets/

I'm almost wondering if I could manage to make a narrow gabion cage/wall/basket/what-ever-they-called to encase the sides and back of my woodstove....


We're thinking of visiting a local rock place and seeing what they have there that's cheap and retains heat. If they have soapstone bricks or similar, maybe well get those. If they have granite rocks or cut-offs from granite countertops, maybe we'll get some and fill a cage with them.

William Bronson wrote:Your place looks nice, that seems to be one if your concerns,so stacked stone or a gabion baskets might be too messy for you.
I've seen water recommended as a thermal mass.  

Tee-hee, you didn't see all that was cropped out of the picture. We have a one-year old and a four-year old, in a 1,000sqft house. It's a mess! I do try to make things look nice if I can, and so it's a plus if something useful turns out to be aesthetically pretty. But, we're also poor, so something being affordable is really nice. And, something not taking much time is even nicer, as time is always at a premium!

Travis Johnson wrote: In my case I live on a concrete slab on grade so weight was never an issue, but on a typical frame house it might be. A few posts in the basement or crawl space propping up the framing above would be a quick, cheap answer.

We're thinking of, when we transform our attached garage into a family/multi-purpose room, we'll put in a rocket mass heater. I look forward to not having to worry about needing to support all that mass! I have no idea if I can convince my husband to go under the house and add supports to under the woodstove. The man HATES spiders. But, I'm hoping that since our house is so small (just under 1,000sqft) it won't take too much mass to make a difference.

David Livingston wrote:Make a stone chimney maybe  
What are your walls made of ? We took off the plaster and got back to stone made a big difference
David

I don't even know how to go about making a stone chimney, especially since my stove pipe goes straight up. Wouldn't I need to build a lot of surrouronding structure to hold the weight of the chimney?

Our walls are manufactured home walls, so studs and thin, cheap drywall. The wall on the left in the picture is an interior wall. The wall on the right is an exterior wall, so it has cement fiberboard siding ("hardiboard") on the exterior. There's sadly no stone in our house :(

Kind of thinking out of the box here, but to maybe suggest a different direction you could go to achieve the same thing...is sand. When it comes to heat retention, sand beats everything including rock!

Back in the old days they used to put a layer of sand down on the decks of ships and then build fires to cook and stay warm. The sand absorbed so much heat that the wood underneath would not catch fire. And in my own house I use TONS of sand to heat my home. I have radiant heat as a back up heating system, and not wanting to pour concrete over my tubes on an existing slab, I simply covered the pipes with sand instead. It not only worked, it works incredibly well.

I bet if you could find a steel container of some sort about the size of the top of your stove and filled it with sand you would be amazed at how it acted as a heat sink.

I was thinking of this problem whilst harvesting soil * are we all looking at this issue the best way ?
Does sticking things to the fire make any difference ? after all its just moving heat energy around at best there is still the same amount of energy if fact by adding stuff to the fire this will slow down heat coming out of the fire and make the exhaust hotter where upon bye bye out the chimney not good .
Since this is an efficient fire why not treat it like a RMH put in some mass between the fire and the chimney . Sand would do, maybe a simple brick affair filled with sand move the fire a couple of yards to another part of the room and make a "feature" that captures the heat in the chimney . Result fire goes on once a day heats up - couch/ citrus plant stand brick book shelf / modern art thingy - rest of the time it keeps the house warm . Instead of making something less efficient make it more

David  


*digging a ditch

Nicole Alderman wrote:
Oh how I hate pinterst because it almost always leads me to pictures without their actual webpages!

I know right? Pinterest is a leech, little original content and always trying to hack you into their ecosystem.
My only work around us Google image search.
I can often find the original post by looking through the results.

I hear you on the minions,I have two myself,and they leave chaos in their wake!
I doubt I could frame a photo anywhere in my house that looked so nice!


The sand thing is interesting.  A couple sections of 6"vent pipe, joined together to double their circimferance,could go around the existing chimney,then moist sand or cob could be packed in.

Maybe this has been mentioned before.  But what about a hybrid of Nicole and Dakota's system?  I wonder if granite countertop placed have bigger scraps that could be cut to match the shape of the top of the stove.  Then stack 8+" of them on top of the stove.  They'd look a bit better than a pile of rocks or firebricks and maximize the mass in the area.  May not be the cheapest?  

YOu could cast a concrete wall on either side. Or get some old stones of electric heaters they are very heavy.

Mike Jay wrote:Maybe this has been mentioned before.  But what about a hybrid of Nicole and Dakota's system?  I wonder if granite countertop placed have bigger scraps that could be cut to match the shape of the top of the stove.  Then stack 8+" of them on top of the stove.  They'd look a bit better than a pile of rocks or firebricks and maximize the mass in the area.  May not be the cheapest?  

https://permies.com/t/43930/bunch-bricks-regular-metal-stove

This thread:  https://permies.com/t/43930/bunch-bricks-regular-metal-stove

....has some additional ideas along those lines.  

I put cob on everything for thermal mass. It's cheap and sculpty.

John Weiland wrote:
This thread:  https://permies.com/t/43930/bunch-bricks-regular-metal-stove

....has some additional ideas along those lines.  

That is awesome.  Thanks!

For quick, cheap, and easily reversible mass, I would suggest concrete blocks. A mix of solid 4" x 8" x 16" and regular cored 8" x 8" x 16" blocks will cost less than $2 each, you can dry stack them around sides and back of the stove and make a shell that will absorb a lot of heat and reradiate it, and they can be useful in building an addition or something later, or as part of the mass infrastructure of an RMH.

If you can get "corner blocks" in 8" x 8" x 16" size, they will have neat squared-off faces for exposed end positions in the surround.

I have a greenhouse with an old incinerator used as a wood burner. I got some paver bricks from a friend who will eventually need them back and stacked them as close around the heater as possible from floor to the top of the heater. I also put a layer vertically on top along with a large rock (problem there is this incinerator loads from the top so I have to remove and replace the top ones each time I fire up the heater). The bricks on top get the hottest because they are touching the surface while the ones around it aren't. Seems to help a lot as far as extending the heat time but doesn't give me a more than six hours per burn.   I also have a 125 year old house that originally had round ducts running from room to room to supply heat around the house from 1 wood heater. I incorporated that idea in my greenhouse and ran the exhaust from front to back with a fan blowing down on it to capture some of the escaping heat. I will build a RMH soon so I can get better heat retention.

How can I improve on these bricks to add more mass, without being really expensive or breaking our manufactured home's floor?  

You should  (hopefully?) be able to get underneath you home in order to reinforce structure beneath the floor so that it can support more weight.  I would suggest gathering stone and bricks and scrap 2X4s and such.  Use the scrap lumber to build up blocking (sort of log cabin style with small pieces of lumber) to reinforce your floor beneath the area around your woodstove.  Use the stone (mortared with cob) to build a semi circular wall that is immediately adjacent to your wood stove's walls and back.  Having it touch might not be in your favor.  The woodstove that you have is engineered to throw heat off of it's surface, and not to have heat retained against it's outer steel on it's sides.  Having the stone against your steel might cause the steel to overheat and thus be damaged.  This is not likely happen with a slight gap.  The more dense your mass the more efficient your thermal potential.  


I used to have a small cabin with a wood stove and a 4 gallon pot 3/4s full of water on it.  I would use this water for dishes and washing.  I would also move the large pot onto a stool that sat beside the stove when I wanted to cook. Beside the stove the pot still absorbed some heat, but mostly just remained equalized.

I seldom needed the entire firebox, and it sounds like (by your description of your heating situation) you don't either Nicole.  In my case, I added thermal mass inside the woodstove in the form of large basalt lava rocks. These did not last forever, but they did the job of taking on a lot of heat and keeping it longer in the cabin instead of up the chimney.  

I would also place flat basalt rocks on top of the woodstove beside the pot.  I would use these to moderate heat just as you do.  These would be taken off, a while before going to bed, wrapped in an old wool sweater, and then carried upstairs into the loft and put at the foot end of the bed underneath the blankets.  When I went to bed later, the stones had slowly radiated into the futon, the flannel sheets, and the quilt, right where my feet would be.  Knowing that if I have warm feet when I go to bed, I can let the fire go out without a problem, this would allow for great piece of mind.  In this cabin I did not have running water (so no pipes to freeze), and I would sometimes open all the windows and let the cabin get really cold, just to test the effect of the warm stones by my feet on my quality of sleep.  Sometimes my tea cup would be frozen to the counter when I got up, but I was warm.  The rocks used this way were a great way to extend the heat, long into the night, and thus not use firewood to do so.  I was gathering all my firewood on the beach with a hand saw and a wheel barrow.  This lifestyle is not for everyone.  I was a bit of a freak in those days and would often jump in the icy ocean first thing in the morning before breakfast (and often before lighting the fire)... so there's that!  

When it comes to heat retention, sand beats everything including rock!  

I have to disagree with Travis here.  It all comes down to the density that I mentioned earlier in this post.  Sand has spaces between the individual particles and, while having a very notable thermal mass, sand also has some insulating qualities, unlike stone, or specifically like mortared stone.  This is the reason that a pebble filled bench is a lot less efficient for an RMH than a cob and stone bench.  

And in my own house I use TONS of sand to heat my home. I have radiant heat as a back up heating system, and not wanting to pour concrete over my tubes on an existing slab, I simply covered the pipes with sand instead. It not only worked, it works incredibly well.  

The insulating qualities help the individual sand particles to not lose heat once they have received it from the water pipes, and thus give it some longevity once it is hot, but I would hazard to say that a solid slab would hold more of the water's heat quicker and longer.  

Back in the old days they used to put a layer of sand down on the decks of ships and then build fires to cook and stay warm.

While it is true that sand below a fire will retain some of the fire's heat, sand laid under a fire (common practice in the old days under many firebox wood stoves or fire places), is to serve the dual purpose of both the absorption of heat and the insulation of the wooden structures underneath.  Some manufacturers suggest that a person put sand on the firebricks in a woodstove for the first burn before an insulating layer of ash has been produced, to protect them from thermal shock

I bet if you could find a steel container of some sort about the size of the top of your stove and filled it with sand you would be amazed at how it acted as a heat sink.  

If that steel container of full of sand was then saturated with water then you'd really see some serious retention of heat that would far surpass the sand in the pot alone.

In everyone's opinion barring any restrictions, what is the best thing to use for thermal mass and why?

Jeffrey Sullivan wrote:In everyone's opinion barring any restrictions, what is the best thing to use for thermal mass and why?

Robert made some VERY GOOD points so I might stand corrected. I have walked across a sandy beach on a sunny day barefoot and know it absorbs heat, but he might be right that I am getting heat absorption, and cost per unit confused. At $2 a cubic yard for sand, and $100 for a cubic yard of concrete, he is probably right on heat retention. Myself I cannot make a definitive point because my experience is not very comparable. Half my house has radiant heat with pex in the concrete, while the existing part of the house has radiant heat tubing embedded in sand over concrete. Both heat the same, BUT the latter one is one big room, where as the embedded pex tubing are in the bedroom areas and thus intersected by insulated walls. (Every wall in my home is insulated, even inside walls for sound and zoned heat).

But all that aside, in my house, in the section we used in-slab pex tubing for the radiant floor heat, we put in 400 ton of rock under the slab. I have felt that worked incredibly well. Naturally I insulated the envelope very well with styrofoam, but my 2500 sq ft home only uses $1800 worth of propane a winter season here in Maine. That is pretty good. Some online people that love heating stuff said this is great and was smart of me to do, and some say it was stupid and a waste of money.

Myself, I do not really know.

I know it is nearly impossible to get my home below 57 degrees. Its footprint is so big, and the structure is so well insulated, that it really is hard to bring the home below ground temperature.

In my case I chose NOT to go with passive solar heating, and instead went with super insulation. I have few windows, what ones I do have are rather small, all basing it on the premise that insulation is R-25 and a window R-5. For my house, while I do not have it now, I think active solar gain (versus passive solar gain) would be best. With the monolithic slab, super insulation, and 400 tons of rock; I think I would get the best control and use out of that solar heat.

In everyone's opinion barring any restrictions, what is the best thing to use for thermal mass and why?

As with many things in permaculture, it always depends on many variables depending on your local resources, personal needs, and the ability to function it well into your existing system... but barring restrictions:  I'd say it's probably a toss up between water, oil, stone, or mineral dense (heavy saline) water, cob.  Oil being the least likely to be used, but is a great option for the innovator who has it in abundance.  

Although I'm no master of physics or even the sub category of thermal dynamics I figure I can give you some rough ideas about thermal mass.  So the queston of 'why' can be broken down to this: The thing about thermal mass is MASS.  So most any massive material can be used for thermal mass in some situation.  The denser the material, the better it is as thermal mass, for the most part.  Stone will be better than cob.  But cob would be better than straw bale; the latter of which holds a lot more air.   Various types of wood have different densities and thus will hold and release heat in very different ways; oak is better than cedar.

To complicate matters, it also depends on the thickness of the thermal mass.  A 10 inch cob wall might not provide nearly as good thermal mass as a two foot thick uninsulated cordwood wall that are both equidistant from a woodstove in the interior of a house.  A two foot stone wall will likely be much better thermal mass in the same situation, unless the stone is pumice (which holds a lot of air).  

I don't have the stats, but I would hazard a guess that a foot thick of stone will likely be better than a foot and a half of cob, or seven 45 gallon plastic barrels of water, but a three foot thick cob wall would probably be better than a foot of stone.  

To further complicate things, if the thermal mass is coming into contact with the earth's ambient temperature (as in a slab on grade, or as in an 'exterior' wall that is backed onto a berm), and it is not insulated, then the Earth itself becomes part of the thermal mass but the lag time for gain and release would be much slower.  

Then there is context for use:  If a seven inch wall of stone were backed by an R24 fiberglass insulated wood stud wall, and the wall of stone was heated by direct sunlight, then the majority of the solar gain will be absorbed into the stones full depth and then re-radiated back into the sun side of the wall.  If same stone wall was two feet thick, it might need considerably more direct sunlight in order to re-radiate the heat.   If the same stone wall did not have the insulation, then the thermal mass of the stone would radiate also on the back side into water space was there.

       

I have walked across a sandy beach on a sunny day barefoot and know it absorbs heat, but he might be right that I am getting heat absorption, and cost per unit confused. At $2 a cubic yard for sand, and $100 for a cubic yard of concrete, he is probably right on heat retention. Myself I cannot make a definitive point because my experience is not very comparable.

 Hi Travis.  I might have miss-wrote in a way, because I think that your idea is great, and I don't want to detract from it's potential.  I think that your experience is quite valuable, and the example of using sand as thermal mass is a good one.  That is, it is a very affordable and simple solution that does indeed perform the function; I was trying to point out that sand is perhaps not quite as good of a thermal mass as other materials (in spite of your positive experience), not that sand was necessarily a bad choice in certain situations.  You seem to have found one of those situations.  The insulating qualities of sand might be working to benefit your system, allowing a shallow sand area, heated by radiant pipes, to release it's heat slower than it otherwise would if it was a denser material, since the insulating quality stops some of the heat from being transfered out right away.  

As far as walking across a sandy beach... I am reminded of being on the west coast of Guatemala, and the beach was black sand.  It was my 22nd Birthday, which is early January 1992, but despite not being summer the black sand was scorching hot.  I remember that in order to not burn my feet I would be wearing my harache (homemade sandals of old tires and leather by peasant artisans) sandals down to the tidal edge, so that I was on damp cooler sand, and throwing my sandals back so that I could swim and have the tide not take them.  The thing is, if you dug down a short distance up the beach where my towel was with my friends into the hot dry sand, the sand was cool not too far down; it was only the surface layer that was super hot.  

The same when I was doing survival courses in the South Central desert of Utah.  I would sometimes bed down on the inner curve of a small dry desert creek, where the sand deposits are nice and deep.  If I bedded down at the right time, when the sand was still warm, then my blanket insulated the sand from radiating it's heat quickly away into the clear cold night, but the sand was not deeply warmed, and the sand beside my blanket lost it's heat to the clear cold night quite a bit sooner than the stuff under the blanket.  The best was to insulate the sand with some scrub oak leaves, and ponderosa pine needles first; the deeper the better; an 8 to 10 inch bed of desert forest debris made for a dream sleep if put on top of radiating sand, but it was even better on radiating stone.

I just piled a single layer of bricks around 3 sides of our stove.then I could pile logs between the bricks and the sides of the fireplace. That gives a good drying place for the wood, and tones down the heat from the stove.

Next, providing the heat needed isn't too high, I put couple of 3" dia logs on in the evening, and let them burn through to charcoal. This is just to get rid of the volatiles. Then pull out the ashpan, and tip the ashes over the coals, starting at the front and gradually moving the pan towards the back of the stove. Make sure it's completely covered, then smooth it over to give an even thickness of ash, shut all the vents (and the door) and let it go. It will stay at about radiator temperature till the morning, when I rake it through, open the vents, put a couple of logs on and let them burn through, and repeat the process. That way we have a comfortable temperature for the cost of 4 small logs , every 24 hours.

We also have a couple of kettles of water on the top, so we ket some hot water morning and night too.

Nicole, the amount of thermal mass you would need to be effective would certainly necessitate structural upgrades. Because you would need tons to store significant amount of heat. But your problem is common with woodstoves in smaller houses. The best solution (if money were not an issue) would be to replace your stove with a catalytic model like the Blaze King Ashford, Chinook or Sirocco. These stoves can burn cleanly at much lower BTU output levels and burn many more hours on the same load of wood.

If you don't want to buy a new wood stove, I suggest that your problem could be improved somewhat by optimizing what you have. If you could make your stove burn cleanly at lower burn rates you could maintain a more comfortable home by reducing temperature swings. You would also need to load the stove less often and would burn less wood while staying more comfortable. The problem will still exist but to a lesser degree.

To achieve this make sure your stove is in optimum working condition. Check your door gasket for air leaks by shutting the loading door on a dollar bill. If the bill can be pulled out too easily that indicates you either need to adjust your door latch or replace the door gasket. Neither job is difficult. The door on your stove is adjusted by using a suitable "cheater" bar to bend the inside portion of the door handle closer to the door. If the dollar bill is not held tightly all the way around the door frame then you need a new door gasket. You can check your window gasket for leaks with a burning match when you have a good fire going. The flame will bend towards the air leak.

Your stove has high temperature baffle boards and insulation batts installed above the secondary burn air tubes. If these are in poor condition or not placed properly it will not allow your stove to burn efficiently and cleanly at low burn levels. Reposition correctly or replace the boards and insulation to factory specs. More information can be found in your Owner's Manual:

http://ironstrike.us.com/system/document_files/files/000/000/359/original/900126-00_B_IRN_S160_Wood_Stove_EN_IICO.pdf?1480966436

I love heating with carbon neutral wood heat and it's even more of a pleasure if you have a stove that can burn cleanly at low burn rates.

I just piled a single layer of bricks around 3 sides of our stove.then I could pile logs between the bricks and the sides of the fireplace. That gives a good drying place for the wood, and tones down the heat from the stove.

Roy Clarke, please tell me I miss read your post.  This sounds like a serious safety hazard.  Wood stacked against the stove is at risk or igniting.

   I just piled a single layer of bricks around 3 sides of our stove.then I could pile logs between the bricks and the sides of the fireplace. That gives a good drying place for the wood, and tones down the heat from the stove.

Roy Clarke, please tell me I miss read your post.  This sounds like a serious safety hazard.  Wood stacked against the stove is at risk or igniting.

I think that you misread that, Tim.  The way I read it, the bricks are piled up in a a 'U' shape around the stove, but there is room to pile logs in between the brick 'U' shaped wall and the stove.  There is no indication in what Roy wrote that would lead me to believe that he has the wood stacked against his stove, but as you point out, it is not written clear that the wood is not in that place.  And I agree that such placement would not be in his best interest.  I hope that Roy ads some clarity to be sure, though!

Roberto pokachinni wrote:

   I just piled a single layer of bricks around 3 sides of our stove.then I could pile logs between the bricks and the sides of the fireplace. That gives a good drying place for the wood, and tones down the heat from the stove.

Roy Clarke, please tell me I miss read your post.  This sounds like a serious safety hazard.  Wood stacked against the stove is at risk or igniting.

I think that you misread that, Tim.  The way I read it, the bricks are piled up in a a 'U' shape around the stove, but there is room to pile logs in between the brick 'U' shaped wall and the stove.  There is no indication in what Roy wrote that would lead me to believe that he has the wood stacked against his stove, but as you point out, it is not written clear that the wood is not in that place.  And I agree that such placement would not be in his best interest.  I hope that Roy ads some clarity to be sure, though!

Haha, I think we'd better wait for Roy to clarify.

My impression was that he has a woodstove installed in a fireplace with the stovepipe running up the chimney, put bricks up against the stove, and stores wood in the remaining space of the fireplace.

That is funny, Jan!  I had thought about his use of the words fireplace and woodstove as simply referring to the same object (a common reference for some people in my world), not that the fireplace and the woodstove were potentially separate things, as you have seen it.  Re-reading his post, I can see how you would interpret his statement the way you did as well.  English is a remarkably subtle and potentially baffling language, considering how it adapts.  I feel fortunate to have it as my first language instead of having to puzzle through it from the outside as a second language.  It's potentially confusing enough as it is.  

I'm tinkering with mass inside my stove, and overall I like it. But it does smoke more when the door is open.
Three of eight bricks used as a ceiling have cracked this fall, fire bricks might last longer. There is a two inch gap between my ceiling and the stove ceiling and a six inch plus hole in my ceiling to allow smoke to pass.

Tony Davidson wrote:I'm tinkering with mass inside my stove, and overall I like it. But it does smoke more when the door is open.
Three of eight bricks used as a ceiling have cracked this fall, fire bricks might last longer. There is a two inch gap between my ceiling and the stove ceiling and a six inch plus hole in my ceiling to allow smoke to pass.

Ideally the thermal mass is outside the firebox because otherwise the thermal mass will maintain a lower temperature in your firebox which will hinder complete combustion and you will go through 2-3 times as much wood through the winter trying to stay warm. And when your fire does burn out, all the heat in your thermal mass will go up the chimney. Well, not all of it, but most of it. Thermal mass works both directions. It might take a long time to cool down but it also takes a long time to reach high temperatures which is what you want in your firebox.

Secondary combustion works best when the top of the firebox can reach 900-1200 degrees F which is why modern stoves tend to have insulating rigid mineral board and/or ceramic insulating blankets for smoke shelves. It increases the heat output per cord dramatically and reduces hazardous (and inconvenient) build up of creosote. Less time spent cleaning your chimney, cutting wood, packing wood in the house and stacking wood = more time to read, drink beer, eat, have sex, hunt, etc. = more happy!  

Tim Siemens wrote:

I just piled a single layer of bricks around 3 sides of our stove.then I could pile logs between the bricks and the sides of the fireplace. That gives a good drying place for the wood, and tones down the heat from the stove.

Roy Clarke, please tell me I miss read your post.  This sounds like a serious safety hazard.  Wood stacked against the stove is at risk or igniting.

Tim Siemens, as requested, you miss read my post.

Roberto pokachinni, the stove is the iron/steel box that the logs are put into. The fireplace is the structural space where the stove is located.

Jan White, your interpretation is correct

Does anyone know if I could use 5 inch roll of iron and put besides the wood stove as high as the stove?

Hi Mae;  Welcome to Permies!
Yes, you can hang an iron roll next to your stove! It will make a fine extra mass.

I would think about anything would work, I prefer metal to brick or stone. You can also move and save the heat other places. A metal fish basket full of coins, old stainless steel flatware or whatever works great.  You can heat it on the stove and wrap it a in blanket to keep your feet warm or get it really really hot and drop it in a bathtub. In the latter I find it easier and less messy to move the heat than to move hot water and avoid something that easily rusts. Don't use glass marbles either, they can crack when they hit the water.  Our stove sets up against a brick wall. On the other side is a modified metal file cabinet where we keep cast iron kittles and the like.

Someone asked me if I had an update, and oddly enough, today was a perfect day for an update!

My parents just got new soapstone countertops, and they got the extra cuts of soapstone leftover from making the countertops. They cut a piece down to fit perfectly next to my woodstove!

So, here's the things I've done to add mass to my stove:

I walled the whole backside behind my stove with light-weight old chimney bricks I got from a local homesteader who wanted them gone

I extended my bricktower on the left side of the stove all the way to the top. I've noticed that the lower bricks don't really ever heat up. They stop being cold, but don't get hot. So, if you're investing in some dense material to add mass, add it next to the top of your stove

I topped the brick tower with the large soapstone slab my dad custom cut to fit there. This thing is awesome! It heats up nicely, and it's also a great place to put pans to stay warm, or to put a plate to hold pancakes while I make enough for the family

Drystacked bricks infront of my woodbox--both to keep the woodbox safer, and also to retain heat. The bricks in the back don't really heat up, but the ones in the front do get warm

Put soapstone and granite pieces (that I'd gotten from the local homesteader who'd bought her property from a countertop maker, and who wanted the granite/soapstone gone). This helps hold the brick wall in place, and it also retains heat, and it's a great place to put my bowl of batter when making pancakes/hashbrowns/waffles, etc

I covered about 1/3rd of the top of my woodstove with granite/soapstone, and put a giant pot of water on top of it all. The small soapstone area is a nice place to melt butter or keep small pots of oil/gelatine or salves warm and liquid

Before I had the lovely soapstone slab my parents brought today, I just had a mish-mash of granite & soapstone on top of my brick tower. You can see it pictured when I made my hide glue for my leather-bound book



Here's my current arrangement"

What we have done with a barrel stove (wood heater) in our basement is use concrete building blocks (i believe 8" x16") They are stacked as a traditional
wall with a bit of spacing 1/2 " on the bottom layer that allows air to be drawn into the system. It has worked well with a small contact area on the curve
of our heater.   Yours would be better and you could do a three sided wall structure. Also the lower portion though not touching will draw some heat from
a slightly closed area.   Don't expect it to get real hot - if it does you are probably wasting wood!  After the fire goes out it will still radiate for a few hours
even though feeling slightly warm - trying sand might be a later option with the structure (we haven't done so). (we are 40 plus year woodstove users in
temperatures averaging -10 celcius but hitting more than -30C  for periods some winters).

Hope this helps Peter in central British Columbia, Canada                     super efficient wood stove design (used for 4 years) on our other place
may be coming up in the future.  

Why not build up the exterior of the sides of the stove with a high heat cob? I use crushed granite instead of sand and then clay and finely chopped straw for a high heat cob. We made our rmh with this in part. The riser is vermiculite and light clay slip into a form.

Nice to see someone else from Maine. In my house, I had passive solar with windows facing the sun and a big field. I had an unbelievable amount of insulation in attic and double thick vapor barrier for each individual room.  The house would heat itself in just about any cold weather we have in Maine.  There was a lot of mass in the house structure. Usually we would end up cracking a window because the house was built too tightly.  I had an outdoor wood boiler that was very efficient at getting all the btus out of the firewood by burning at a high rate and not smoldering. Heating up hundreds of gallons in of water and then having a traditional thermostat connected to circuitry that controlled a circulator pump made for great even heating. Lots of times there would be little to no smoke and if a person was in the house they would not even realize it was being heated by wood.

Sounds like you have a great set up. Winter is coming!

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