Masonry heaters

Hey Rod, I just noticed this kit for your 55 gallon drum heater.

http://www.lehmans.com/shopping/product/detailmain.jsp?itemID=199&itemType=PRODUCT&iMainCat=671&iSubCat=737&iProductID=199

from what I have read it is possible to have a stove that is too large. If the weather becomes considerably warmer than you anticipated when you fired, your house will be too warm, and if the temprature falls the house will be too cold. Masonary stoves do not heat up fully until well after the fireing. So, even if you re-fire in the event of colder than anticipated weather, the house may be cold for a while. The length of time the stove needs to heat up and cool down depends on mass so if it is too large your weather forcasting skills may not be enough.

5000-10000 lbs seems to be a normal size for one of these stoves giving 12-24 hours on a firing. Rreidnauer's stove fits into that sizing, so he will not have to predict weather days into the future

Tom Elpel (LHBA member) built one and it is featured in
his book "Living Homes". Seems to be very effecient and
stores heat for a long period. From what I remember it
was very inexpensive.
-Rick

I haven't received a quote for an installation, rather, I cumulated my numbers from extensive searches online, when I was considering heating methods for my future home. $60,000 sounds incredibly high, but I guess geography can play a large part in such installations. (and of course, the size of the heater and associated foundation)

I never read much on sizing masonry heaters to the square footage of a home. Rather, it seems the plan is to build as large a mass as you can for an available space or budget. The reasoning is, the larger the structure is, the longer you can go between firings, and the more evenly the heat will be released from the mass. If I recall right, I think it was recommended that your mass should be no less than 2,000 pounds, with more obviously being better. Personally, I think 2,000 pounds isn't even close to enough. I think 5,000 pounds should be a bare minimum. My design (with a 30 gallon firebox) would have 3,000 pounds of dry sand, and a masonry surround should give you close to the other 2,000 pounds. I can envision where a large custom built heater could easily go 10,000-20,000+ pounds.

I think 7-10K would be for optimum conditions, such as having an adequate foundation to build upon and chimney availablity/options, and a structure of conservative size.

With a masonry surround, yes, I think 12 hours would be reasonable. Time will vary by how efficient the home is and climate conditions. It won't be nearly as efficient at extracting heat from the fire as a professionally built heater, so you will have to burn more wood a bit longer to get it well heat soaked, but for the price, what can you expect?

Didn't see your post while I was typing rreidnauer. Building one from scratch sounds a little daunting for me. But you never know. Do you think the home built one will supply 12-24 hours of heat? This does sound like an interesting source of heat though, I will have to look into it some more.

That doesn't sound too bad, considering the return on investment. I was reading in someplaces that they could run 30-60k. I don't know what type they were talking about though, and the suppliers in the links at the start of this post don't seem to have prices but ask you to call them for consultation. So, 7-10k doesn't sound bad. Could I ask what was the size of your home you got the estimate for and what type of heater was it?

Wow, there's a tough question to put a number to. You can expect masonry heaters to cost $3,000 to $7,000 for "kits", with some going up to $15,000 to $30,000 for custom built! There are so many variables. The way to get best savings is to build your own. For example, this website has plans which claims you to build one for around $1,000.

Or, you could go with my earlier mentioned idea for the "Tank, Drum & Sand" method, with a simple mortared brick or stone jacket around it to pretty it up. (and add additional mass) This could be built for little more than the cost of the mortar and stovepipe, if you scrounge up the rest.

Its been more than a couple years since I had figured out what it would cost me and if I remember correctly I was coming up with a cost of $7k minimum for a basic masonry heater and I think that was with me doing most of the work. Hiring someone 10k is sticking in my head.

Just out of curiosity, what type of cost would we be talking about for a masonry heater for a log cabin? Nothing exotic, just something nice to look at and functional that would supply heat for 12-24 hours.

Was just there three days ago. Wrote myself a
note, took the camera, and remembered just
after the neighbor left to go to town for the day.
Next time for sure!
-Rick

Rick, did you ever get that picture of the "keg-o-heater"???

Nope...nuthin'.

Just a thickwall beer keg.

Maybe I can remember to
get a photo on my next trip.

No swirl chamber, no secondary
or primary heated air source, and
no outside air source. Almost
looks like a joke but it does the
job very well. I was impressed.

-Rick

Wow! Is he doing that with the benefit of a heatsink, like a sand jacket?

I'd be worried about a burn-through without one, but I admit, I don't have any experience of lighting a fire in a beer keg to make that assumption.

Hey Rod,

My neighbor just removed the expensive wood stove from his garage
and installed a cheap ($100!!) beer keg wood stove. Since I had
experience with the old double 55 gallon drum stoves I just rolled my
eyes. That thing works great! The price was right, no fabrication was
needed on his part, and the garage is finally warm...if fact, almost
hot when the temperature outside was in the teens. It does smoke
a bit, but the thing does work well, and the fuel burn is low.

-Rick

Your 55 gallon drum wouldn't rust from the sand. Like you said, having a fire in the drum would dry out the sand and keep it dry. Dry sand won't rust steel very quickly. The fire on the inside of the drum is another story.

Water vapor is a product of combustion. No matter what kind of fuel you are burning, water vapor will be part of the "smoke". Dry wood will have less than wet or "green" wood, but even burning coal, oil, gasoline or propane will still give off water vapor. (When I say burning gasoline, I mean in a combustion engine. Don't try burning gasoline, it doesn't work well and it seems to take forever for the hair to grow back on your arm.) Combine that with the heat from the fire to burn off the protective coating on the steel and you will have rust quicker than you think.

On the positive side, I know loggers and mechanics in the area that have had barrel stoves in thier shops for years. Yes they are rusty, but they don't rust completely through for a long time. And I know one shop that burned hot fires. They had a small resevoir for used motor oil and a 1/4" pipe that ran to the fire drum. The pet cock would be opened after the fire was hot enough and it would increase the intesity of the fire. A couple of times someone forget to shut off the pet cock and the barrels got red hot! But they stayed intact.

Having the drum surrounded in sand would transfer the heat by conduction and pretty much work the same as a masonry heater (in theory). I am anxious to hear how well it works in real life. I am guessing that the worst case scenario the drum would have to be replaced every 5 or 10 years (depending on use). It might be possible that the drum could last for as long as 20 years or more, but that's just my own opinion.

Good luck, and keep us informed.

I was thinking about using a stainless steel container that is used to keep milk cold, for a home made hot tub. They have a sort of radiator type of inside that moves liquid around the sides of the container. It may be possible to pipe in the hot water from my big wood burning stove which already has the connections for water. (convection?) Maybe a few pressure release valves etc. It would be pretty cool sitting in one of those big tanks in winter using just wood heat, which was heating my shop already. I see those tanks outside one dairy or another just sitting there for years.

Here in GA we have a publication put out by the state dept. of Agriculture called the 'Market Bulletin'. It has advertisements from farm folks for various useful things. Every issue has folks with plastic and steel used barrels for sale. Some of them have stainless as well. I'm not sure how thick they are, but its a start. IIRC, a lady I bought some plastic barrels from had quite a few stainless ones, and they were only used once due to some food grade regulation?

It just hit me, though smaller than a 55 gallon drum, an old stainless beer keg could make for a decent, cheap, heavy-walled fire box.

Wonder if a place like a dairy farm would have any scrap stainless tanks or drums. Hmmmmmmm

Good point, and you're quite right. But I wouldn't be too concerned about 'the man' coming in my house to see my homebuilt heater. Though, it could cause a claim on your homeowner's insurance to be denied, should you ever have to make a claim related to a fire incident. I think government regulation seems to concentrate more on exhaust emmisions and spark arresting equipment, rather than the the heater itself, but I've been known to be wrong. :wink:

As for all the automation equipment, you're delving into the world of electronics, and for me, it's a bit of a dark, unexplored land. Simpler terms could be done, like common bimetal thermal snap switches or a simple wall thermostat for temperature control. The commercial wood boiler makers already have automated damper controls. Take a look at their designs.

But, I never intended on such controls, as they are not needed. Just like a masonry heater, it is designed for a fast, hot burn. And then coast on it's thermal mass over the next 12 hours or so. A slow burn is inefficient and unnecessary, since it's the job of the thermal mass to regulate the release of heat. It's also the reason for a sizable firebox, though a smaller barrel, like a 30 gallon one, can be substituted. (and increase the thermal mass with an additional 25 gallons of sand) I've been thinking a 30 might be better. The dampers are really only there for after the burn, to prevent a convective draft of the chimney wasting heat.

I did think about a adding a coil of tubing in the sand, not so much for steam, but hot water. If I had a spell of sunless days where my solar hot water system doesn't contribute, it'd be nice to have a backup option.

by the way, has anyone ever done any steam cogeneration with something like this? I asked the folks at seton about it, they say it will only make power when you have a heat demand--i.e. winter. I think you could make power even when you don't have a heat demand with this kind of system.

You would just put the water coils around the firebox and run them to a steam engine... running a generator. If your firebox puts out 50kBTU/hr, that corresponds to 14.6kW, or 19.6hp. You couldn't get all of this in the form of electricity, but say 25% overall efficiency wouldn't be unreasonable.

3.6 kW might be OK run a very hot fire a couple times/week and you can charge your batteries for the rest of the time--or to run high load implements like power tools for short periods of time. Due to the huge thermal mass, the heat would't dissipate immediately, and your house wouldn't get too hot. However, I would recommend a nice upflow to a large opening skylight for summer use.

Anyway, this would work best in the winter, as you could run it all the time (or whenever you needed power) alongside your heat needs...good for when the skies get dark and the solar isn't putting out much.

rreidnauer's idea for thermal mass using a two tanked system is a good one... However, in WA state (and in the US in general) they have some laws that make it very hard to build your own anything... http://www.chimneysweeponline.com/hohmade.htm

However, I am planning on making a similar design anyway using some basic thermodynamics, possibly an O2 sensor and a couple of thermocouples hooked up to my laptop through telephone (maybe CAT-5) wire. The sensors will run a feedback loop that will automatically open and close the dampers based on several things (the desired temp in the house, the rate of change of temp in the house, the temp of the sand in the outer tank, etc).

Ok, so maybe I'm getting ahead of myself... all of these sensors. Can anyone think of a simple way of regulating the O2 input automatically without
1) manual adjustment
2) electronics that have a tendency to break?

If I can't do it the simple way, I'll just do it with redundant electronics.

In short, I am convinced that thermal mass is the way to go. Further, with secondary firing, this stove can be extremely efficient and long burning. I am willing to make provisions in my home for it, and build it later (albeit probably with a smaller firebox--55gal would heat a small commune--especially in WA), and take my risks with the man.

Yea, it's quite possible for it to rust out eventually. Though, corrosion needs moisture, and if you loaded it with dry sand to start with, and subsequent heatings to well over boiling temperatures, it's going to stay dry. If you'd be really worried, just heat it up good and hot, and plugged the bungs in the top once any noticable steam has vented off.

I'd say there's a better chance of rusting from within the combustion chamber during the off season. That can be controlled with a can of Pam cooking spray at the end of the heating season. Burning good seasoned wood and NOT burning trash in it will extend it's life as well. The heaviest 55 gallon drum I know of is only 16 gauge steel. Oil tanks are usually 12 and 10 gauge steel, and will easily out survive a 16 gauge combustion chamber.

They do, in fact, make stainless steel drums, though they cost 10 times that of a steel one. And, I can't weld stainless.

Besides, If it does rust through, it doesn't cost me much. (except labor) I figure I can make one from a salvaged drum and tank. I figure the most expensive parts would be the stovepipe and loading door. Total cost? Maybe $200. With some care, there's no reason you can't get years of reliable service from one before failing.

Do you think that over some time the 55 gal. drum inside the fuel tank would corrode from the sand coming in contact with the outside skin? My only observation on this system is how would you go about repairing/replacing if the 55 or 275 would rust. I guess that if the 275 would rust there would be no harm, no foul due to the surrounding stone/block/or brick to hold the sand. you would never be aware of it. But the 55 would worry me. Do they make a stainless steel 55 ???

Yea, I would add a damper/cleanout on the front that enters below the grate. Picture revised to include that detail.

Ingenious Rod. I love it. But do you think it might need some sort of air inflow? Seems like it might burn itself out because of lack of Oxygen. Or were you thinking of it with an open front?

After reading an article from Backwoods Home Magazine, I had a spark of imagination to build an inexpensive wood-fired, thermal mass heater. They described using a 55 gallon drum or a heating oil tank as the combustion chamber and surround it with brick/block/rock to absorb the heat. My idea takes things a step further.

The dimensions of a 55 gallon drum and a 275 gallon heating oil tank work out really well for combining the two. My idea involves cutting a hole in the end of the tank, near the bottom, the diameter of the drum. With the hole opened up, you can plumb some smokepipe that would depart the drum at the back, about a 1/3 of the way down. There would be room in the tank for the smokepipe to come up and across the top of the drum, and exit the tank near the front. A grate would be added to the bottom of the drum, and a loading door and damper added to the front of the whole thing. It would look something like this:

Now, here's the neat part. Once it's all welded up and positioned in place, start adding in dry sand through the old pipe ports on top of the tank until it's filled up solid. This would make for a significant amount of thermal mass. You could fill it with concrete too, but if you ever had to move it later, you'll wish you didn't. And, if you don't like the thought of an oil tank sitting in your living room, you can still enclose it in brick or stone, further adding to it's thermal mass.

Seems like a pretty frugal way to build an efficient heater, as barrels and tanks are pretty easy to come by. (at least around my parts) If you can weld, you're really ahead of the game. (I can, yippee!)

has anyone heard of attaching an active solar system to the thermal mass of a wood fiered masonary heater. active water probably won't work due to the dangers of steam when you have a wood fire burning, but an air sysem might. The mass of the stove just seems like a tempting storage spot for solar heat.

we use rumford designs in our historic homes. They are not the drafty-wow it's cold in here when the fire is going style fire box. Look for it on our website www.1909house.com Our mason is Portland Chimney. Portland, Oregon.

We were (allegedly) on an automatic delivery for propane. Somehow, the supplier thought we went to another company so did not deliver. We were on fumes. Obviosly, DUH, I need to look at the tank once in a while. Now the way it was explained to me goes like this; the direct vent unit we have comes with or without an off switch for the blower motor. In the event you get down into the "mix" which is basically fumes and the additive, and the boiler won't fire, the mix should be blown back out. That explains why my neighbors all freaked from the smell. OUr's did not turn off, however so we had to kill all power and the valves because I did not know what the heck was going on. Sooner than later that motor would have died ($$$) luckily we had no frozen pipes. The company magnanimously offered us a $25 rebate for our trouble. The delivery guy ( who put $1400 of propane back into the tank) told us we should have gone with oil. And then he told us not to pay for this delivery! only in "New Joisy"......... Thankyou to all members who responded to me that night.

Clairenj - what was wrong with your propane boiler?
I have problems with a servel refrigerator not burning properly, and my propane heater will occasionally blow out when there are very high winds. (Does the nj stand for New Joisy?)

call 911 and tell them you smell gas; the gas company WILL come out.

Is anyone on the forum now who can give me a pointer about a propane gas boiler not firing? We just got here to the house and the neighbor called and said she smelled propane. I now smell it slightly inside so we hit the kill switch, My plumber who installed it is not answering, the gas company has no emergency nightime # go figure and I don't want to call the firedepartment just yet. It is 11 pm EST. thanks anyone?

I have not seen any gas-burning masonry heaters, personally. I know Tulikivi has an electric backup, with long resistor coils running inside the contraflow channels.

I also would suggest checking into the local building code. The Masonry Heater Assoc. formed with a primary goal of dealing with regulation issues. I know they have successfully incorporated masonry heaters into many wood-fire pollution control schemes.

The EPA currently recognizes masonry heaters as inherently clean burning (when designed, built and used correctly). Heaters are not required to be EPA certified.

Colorado, Washington, and Utah have recognized heaters as a clean burning device and exempted heaters from wood burning bans.
http://www.rmhpba.org/rocky_mountain_region_winter_bur.htm

I believe all wood burning appliances are unfortunately currently banned in San Francisco. That's the only US spot I know currently.

Not trying to discourage you from looking into alternative fuels for heaters, just hopeful that local authorities haven't made an uninformed decision. You may be able to find more information for your new urban home location burning regulations talking to the local building inspector.

Klip

That actually sounds like a very interesting twist on this type of heater. If you can match the BTU's to a load of wood, I see no reason why it's wouldn't work. Automatic and clean operation to boot.

Great info!
I have another question for you.
We may be looking to build in an area of the city where they don't allow you to burn in fireplaces... yeah, I know ... It's not where I'd normally build, either. But, because of the incredible deal on the lot and the great resellable/desireable area, we are considering it. I still like the idea of the masonry heaters, though.
Would it be possible to make a 'masonry propane heater'? or something other than wood? Would it even be worth it? Could you heat up the mass of the heater with another heat source other than wood? - without getting too expensive.. I've just only seen wood-fired masonry heaters...
Thanks for your help guys! (-still no decisions made ... just wanting to learn and collect info!-) :)

Brandt

I've been interested in heaters for about 10 years now. I built one in my home last winter and am absolutely enjoying it this year. I used a design mentioned in the old posts above, from Maine Wood Heat for a Finnish contraflow design.

My only regret is I did not incorporate domestic hot water. It can be done very simply. My natural gas bill has dropped at least 66% this year and I think with free hot water I'd be paying even less.

Masonry heater expert Norbert Senf has the best info on this and almost anything else heater related.

Try- http://mha-net.org/msb/html/hotwater.htm

The most simple plan uses a basic principle of phyics called a "
thermosyphon". It uses a simple 1/2" stainless steel "U" in the rear of the firebox. The water in the loop is heated and rises exactly as hot air rises (fluid dynamics). If you can place a storage tank above the heater, no pumps or pressure is needed. The temperature difference alone cycles the warm water up into the storage tank. This storage tank preheats your hot water before any other appliance. It's a very simple and elegant solution. No pumps or power needed.

Maine Wood Heat also sells a more radiator type heat exchanger for hot water that works on the same principles.

Of course, you can also use pumps to push the water through the heater if the storage tank is not above the heater. This requires careful design of the pump system. During a heater burn, water MUST run through the coil exchanger. If the water doesn't circulate through the coil, it will turn overheat to steam and expand causing a dangerous result. So pump systems may need a battery backup so you can burn during a power outage.

I talked with the MHA president Jerry Frisch about DHW. He is a real believer. He lives in Washington state and said he provides 100% of his DHW as he heats his house with one of his custom built heaters. he mentioned a story to me where his hot water heater's pilot light was out all winter and he didn't notice until the spring when he stopped buring his heater.

Thanks! Awesome! I'll do some searching on that. If anybody has any other ideas or leads on this, input is sure welcome! Thx Greg!

Brandt