Masonry heater retrofit w/ emissions testing!

[EatenByLimestone]

A masonry fireplace was partially deconstructed and turned into a masonry heater. Build along and emissions testing!

 

[begreen]

Fascinating. I love cool projects like this. Thanks for posting!

 

[SpaceBus]

The delivered efficiency is a bit lower than I would have expected. I suppose there is only so much energy in the wood and 10,000 lbs is a lot of mass.

 

[EatenByLimestone]

They didn't mention it in the video, but I imagine getting the stove to initially draft might be hard. I bet the owner has to light a small fire in those little cutouts to get the draft moving initially.

I'd never heard of a masonry
firebox reburning the smoke either.


I find masonry heaters fascinating as the idea of the thermal mass soaking up the heat and slowly radiating it out just seems so attractive. It's really too bad they can't make a modular version of this out of cast iron. Stack up cast slabs on top of each other to provide a burn chamber volume and side chambers for heat absorption. For a larger house you would want a larger firebox and more exhaust baffling. Stack on a few more slabs...

 

[SpaceBus]

I also wondered if there was some kind of flue bypass or another method for starting the draft. There was mention of a flue damper earlier in the video, but I didn't see anything about using it. I too find these masonry heaters quite fascinating, but I don't see very many that are the sole source of heat for a home. Perhaps there are some often glossed over flaws like excessive creosote formation in the "bells" or there just isn't enough mass to make it work, like most rocket mass heaters you see on youtube.

 

[qwee]

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They didn't mention it in the video, but I imagine getting the stove to initially draft might be hard. I bet the owner has to light a small fire in those little cutouts to get the draft moving initially.

I'd never heard of a masonry
firebox reburning the smoke either.


I find masonry heaters fascinating as the idea of the thermal mass soaking up the heat and slowly radiating it out just seems so attractive. It's really too bad they can't make a modular version of this out of cast iron. Stack up cast slabs on top of each other to provide a burn chamber volume and side chambers for heat absorption. For a larger house you would want a larger firebox and more exhaust baffling. Stack on a few more slabs...

I thought that is what the ecco stove was?

 

[qwee]

I also wondered if there was some kind of flue bypass or another method for starting the draft. There was mention of a flue damper earlier in the video, but I didn't see anything about using it. I too find these masonry heaters quite fascinating, but I don't see very many that are the sole source of heat for a home. Perhaps there are some often glossed over flaws like excessive creosote formation in the "bells" or there just isn't enough mass to make it work, like most rocket mass heaters you see on youtube.

Go visit Europe and Asia, there are plenty of them over there - seem to get the job done. In fact, the Germans connect their types up such that they can 'think' knowing when to increase air - and they heat water, too. Creosote build up has never been a problem because the area above the firebox (the first bell?) gets so hot (1200-1800 F) so it acts just like a catalyst combustor - just bigger. It burns up everything, except on start up.

In North America, some companies are selling masonry heater/wood stove hybrids now (mostly made in Europe). But they haven't really caught on. I don't think burners know what they are and how to use them. Obviously, the future will head that direction at some point, especially as regs tighten up the amount of pollution allowed.

 

[EatenByLimestone]

I also wondered if there was some kind of flue bypass or another method for starting the draft. There was mention of a flue damper earlier in the video, but I didn't see anything about using it. I too find these masonry heaters quite fascinating, but I don't see very many that are the sole source of heat for a home. Perhaps there are some often glossed over flaws like excessive creosote formation in the "bells" or there just isn't enough mass to make it work, like most rocket mass heaters you see on youtube.

They installed a key damper above the stove. 20.26 will show you the linkage they had to fabricate for it.

 

[SpaceBus]

Go visit Europe and Asia, there are plenty of them over there - seem to get the job done. In fact, the Germans connect their types up such that they can 'think' knowing when to increase air - and they heat water, too. Creosote build up has never been a problem because the area above the firebox (the first bell?) gets so hot (1200-1800 F) so it acts just like a catalyst combustor - just bigger. It burns up everything, except on start up.

In North America, some companies are selling masonry heater/wood stove hybrids now (mostly made in Europe). But they haven't really caught on. I don't think burners know what they are and how to use them. Obviously, the future will head that direction at some point, especially as regs tighten up the amount of pollution allowed.

True, I've seen videos of nice masonry heaters in Europe and elsewhere in the world, but in the US many seem to fall short in one area or another. How is the top chamber able to reach such high temperatures? Is there an air inlet that allows preheated air to mix with the woodgas and burn? Without an actual combustor or some kind of preheated air inlet I'm not sure how the chamber would get hot enough to do anything other than collect creosote like a normal firebrick lined open fireplace. My main criticism is to the stove they built in the video. It's a far cry from "98% combustion efficiency" and 2+ g/hr is the proof. The 300 df flue temp seems pretty good for a high efficiency appliance, but the homeowner only able to bring down fuel oil consumption by 20% tells a different story. With a 60 lb firebox and assuming the fuel is only 20% water means that totally full that firebox could yield 334k btu over the length of the burn. Perhaps the home insulation is the issue and not the appliance.

 

[qwee]

They had to adapt to what was already there, and it appears to be on an outer wall (not centrally located) which isn't good.

Imagine if you wrapped your wood stove in 5 inches of insulating fire brick (no gaps), stuffed it full of firewood, and lit it off. What would happen? Let's pretend this stove wouldn't get damaged. Immediately, the heat would have no where to go - the temp would skyrocket rapidly. The thick brick or soapstone walls act like this insulating firebrick because the heat transfer through them is so slow.

It is a fascinating play of physics someone discovered. Trap the fire, make it get really hot, it burns everything, create channels the right size, heat rises so force the draft to run in the opposite direction so we keep all of the heat. This can't possibly work - but it does.

 

[qwee]

A Norwegian and an American walk into a bar, in Norway - they order Guinness Stouts. They are both in the wood appliance biz. In fact the American buys Jotul wood stoves from this guy's Norwegian company. They get to talking,

American (A): We Americans really love these Jotul wood stoves that you guys build. They are well made.
Norwegian (N): Yes, we follow close building specs.
A: I suppose in Norway you only use Jotul wood stoves? National pride and all, and they are the best way to burn your firewood, here, right?
N: Not really so. We use some, but we like the little mass heaters in Norway. You Americans love your wood stoves so that is what we send to you.
A: What? You build them but also use other appliances? Why don't you sell these other little mass heaters to us in Canada and America?
Are you holding out on us?
N: Hey we've tried. No one in America wants little or big mass heaters. They only want the wood stoves. You know how Americans are. You have evolved from open fireplaces, after all. And everyone wants to save a buck, and move at the drop of a hat.
A: Ya, I guess I understand now.
N: We'll keep trying. You never know. We can sell little mass heaters that you can take with you if you decide to move, you know.
A: North Americans don't know how to use these things, anyways. Best to let 'em think wood stoves are the best way to burn - it keeps food on the table at my house (both laugh).

 

[SpaceBus]

Americans move too frequently to sink a $10,000+ into a giant masonry structure that the next occupant doesn't care about. Furthermore most of Norway is far colder than most of the US. A Masonry heater in Minnesota, Wisconsin, Vermont, NH, Maine, or Alaska makes a lot of sense, but you are talking about maybe 10% of the US population, probably even less.

 

[qwee]

They use little ones that can be moved, and the cost wouldn't be much more than a good wood stove if there was a market. But buyers are unaware - ok, I mean uneducated.

 

[Corey]

Neat project. At first, I was thinking it might be something I'd be interested in for my masonry fireplace, but WOW, that is a lot of work and destruction to get to the final product.

I'd have to side with others, though, that it seems some of the numbers are a bit underwhelming. The homeowner was only able to offset 20% of their oil use? Though maybe they don't use the heater 100% of the time? Also curious on the 'efficiency' stated. Admittedly, I only 'skimmed' the video. But at one point they seem to show ~74% "efficiency"... which I'm taking to be combustion efficiency - but that is also with 325% excess air. So at minimum, flushing a lot of warm house air up the flue, or possibly even reducing the 'apparent' emissions by diluting 3x over with normal air. Not sure they ever get close to measuring 'heating efficiency' - how many of the BTUs in the wood actually get into the house? Possibly 'not that much'?

I do know that when my stove is 'roaring' like many of the fires they show, it's burning pretty clean, but all that heat is flushing right up the flue...not a lot of heat into the house. I'm sure the masonry heater can capture some of that, but at some point, that is still a lot of CFM air up the flue, and that heat has to come from somewhere.

Also thought it was interesting that after all our years of "clearance to combustibles" - they wrapped the whole thing in cardboard

 

[begreen]

FWIW, Norway has other stove makers besides Jotul and they sold many stoves besides masonry heaters and continue to. Many Jotul stoves are only sold there and not over here. Masonry heaters take up a lot of space and need to be well supported and they are expensive. That keeps them out of many homes in Europe and the states. And they also look somewhat dated which doesn't fit with the contemporary European home style. Tulikivi has been selling masonry heaters in the US for a long time, but with all the caveats.

 

[qwee]

There are little masonry heater hybrids that take up hardly more space than a wood stove. And there weight isn't huge - like 1200 pounds. They aren't that expensive. And I think they look better then wood stoves. People are just unaware of them. To bad, because they are great, green burners.

 

[begreen]

Point being there are lots of non-masonry heaters all throughout Scandanavia and a lot of good stove makers there that don't make them. The anecdote that Jotul makes stoves just for the US market is a chuckle, but not true.

 

[qwee]

I never said they did. Yes, they have a long tradition of heating with mass heaters. It annoys me that this site doesn't promote the best burning technologies available to the public. You should be researching this stuff and pushing it to consumers - begreen, be green. Instead you just lump fireplaces and mass heaters together.

 

[SpaceBus]

I don't think all mass heaters are created equal and I highly doubt a "light" mass heater will be any more efficient than a freestanding woodstove.

 

[begreen]

I never said they did. Yes, they have a long tradition of heating with mass heaters. It annoys me that this site doesn't promote the best burning technologies available to the public. You should be researching this stuff and pushing it to consumers - begreen, be green. Instead you just lump fireplaces and mass heaters together.

That is an assumption. We have had great discussions about masonry heaters over the years. I was lucky to experience a nice Tulikivi install at a friends up in Alaska and we have several Russian fireplaces locally. Search back on old threads.

 

[qwee]

I'll do some more research and start a new thread about masonry heater/wood stove hybrids instead of derailing this one. I'm not sure how new they are - but they are out there. I never hear anything here about them. They should be getting some attention.

 

[begreen]

I'll do some more research and start a new thread about masonry heater/wood stove hybrids instead of derailing this one. I'm not sure how new they are - but they are out there. I never hear anything here about them. They should be getting some attention.

Some years there has been a lot of chat about them including a build of one taking place.

 

[SpaceBus]

I think Qwee is the builder of a masonry heater

 

[EatenByLimestone]

Alaska Heating Degree Days

Says Fairbanks AK has over 13k HDD. That looked like a 50s or 60s house. I bet it lacked insulation. 20% saved on their heating bill might be a couple thousand in oil.

 

[jetsam]

When I was in Holland, even the electric heaters were mass heaters. A portable space heater obtained locally was about 80#, and was composed mostly of bricks inside a sheet metal case. They heat them at night when electricity is cheap and let them bake off all day. The insulation from the bricks makes it a bad choice to warm up an area quickly, but (unlike a steel stove covered in stone), it's not vented and all the heat ends up in the house. It stays warm for a long time after you turn it off.

I can't even find a picture of this thing on google, but I swear I owned one when I was there, and it wasn't something I made!

That said, I don't think many locals used them in urban areas, because gas was everywhere and cheap.