Wood Stove/Masonry Heater Hybrids, Combos

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qwee

Burning Hunk
Jan 17, 2013
134
Idaho
Making a thread about this. I haven't seen a thread looking into these burners. I hope this to be an information thread about the present as well as future possibilities. Mass heaters are common in Europe and Asia, but not as common in N. America. Although, masonry heaters and rockets mass heaters are present in the US and Canada. Of interest, The little appliances (less than 2000 lbs) that aren't traditional masonry heaters but aren't wood stoves either.

This weight is not too far from the largest soapstone wood stoves. I've seen very few threads on these little masonry heater/wood stove-like hybrids. How well do they heat? Do you run one like a masonry heater (1 or 2 fires a day) or like a wood stove (burning 24/7)? Even though it is a masonry heater, can I just run it like a wood stove to heat a larger space? Are these things efficient? How big a space will they heat? If I move, do I just disassemble it and set it back up in my new place?

Typically masonry heaters are site built structures that are massive, greater than 5,000 lbs. I built one that I'm pretty sure is greater than 10,000 lbs. But this thread is about the little hydrid masonry heater/wood stove appliances. They are out there. The intention is to learn about these things. For those who don't know what a masonry heater is here is a video.

 
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qwee

Burning Hunk
Jan 17, 2013
134
Idaho
Anyone out there have one of these little hybrid types? The mini-meat masonry heaters run on the same concept but are much smaller and can even be made out of cast iron. The ones I know of so far are,

Norsk Kleber (from Norway). They must be popular in Norwegian Houses because they are sold all over Norway.
https://norskkleber.com/stoves/kube/

Tulikivi (from Finland) has started selling these mini masonry heaters.
https://www.tulikivi.com/en/products/KOLI_S

Ecco Stoves (from the UK?).
https://eccostove.com/


M Teixerra Soapstone, a US company that were selling small soapstone masonry heaters for $5,000. I don't know if they still are.
https://www.soapstones.com/shop/
 
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SpaceBus

Minister of Fire
Nov 18, 2018
6,301
Downeast Maine
I think the mini masonry heaters only offer slight advantages over a regular woodstove. Similar to a soapstone woodstove vs cast iron vs steel and the convective vs radiant ideas. My cookstove is fairly light and made of inox and steel with lots of heat shielding for low clearances. As a result it is highly convective and can heat the whole house to 80 df but my wife might feel cold because she prefers the radiant heat of the Morso. This seems to be more of a preference thing. These big stationary masonry heaters only have one area of strong radiant heat, and that's the glass door. Elsewise it is several thousand pounds of masonry that is only slightly warmer than room temperature. Probably feels like heating from my wood cookstove vs using the Morso. Maybe some folks like that soft heat release from the warm masonry, many people in this country choose forced air despite my own opinions about it.
 
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qwee

Burning Hunk
Jan 17, 2013
134
Idaho
I see one of the things weighing in at 882 pounds. This one looks pretty light, too. Blowing dish soap though a piece of firewood another way to make sure it is dry?
 

begreen

Mooderator
Staff member
Nov 18, 2005
90,646
South Puget Sound, WA
Thanks for the refresher. This was posted last year too. There has been a lot of talk about masonry heaters over the years. Here is one of the first threads on it.
Back in the day, Marty (Martin Strand) contributed a lot of info on masonry heating.

If one searches on Masonry Heater there are about 67 pages of posts on the topic. It's not really ignored as much as uncommon.
 

qwee

Burning Hunk
Jan 17, 2013
134
Idaho
But there has been very little talk about these small appliances that are basically wood stoves that are using masonry heater principals in their design - and there is a difference between these appliances and traditional masonry heaters.

These smaller mass heaters are 1) more affordable (or could be if more were sold) than big masonry heaters, 2) they can be moved, and 3) they don't require that much floor support. These are three limitations faced by consumers who might consider masonry heaters. These little mass heaters can be very efficient and should be promoted. They are towards the top of the wood burning food chain.

It is only a matter of time that a "wood stove" has tubes, a catalytic combustor, and masonry heater bells (and probably and increase in weight). Maybe there is already such an appliance but I don't think so. We all win if less pollution is created via the best ways to burn wood being promoted. I would guess that less than 2% of the traffic here even knew these little mass heaters existed - thus this post.
 

peakbagger

Minister of Fire
Jul 11, 2008
6,625
Northern NH

St. Coemgen

Feeling the Heat
Feb 4, 2016
325
Hungary
www.stcoemgen.com
I live in Europe. I have experienced both real mass heaters and these smaller types of smaller stoves. In short, the smaller stoves are not real mass heaters. You have to all too often treat them more like a wood stove.

A real mass heaters has a huge amount of mass. One often only needs to light them once a day, burn them hot, and the huge mass stores the heat and radiates it over a long time. These smaller stoves simply do not have the mass needed to really act as a mass heater like that. In fact, many of these type of stoves sold here are simply acting more like a convection stoves. Despite the verbal descriptions in the videos, one would need to see the actual cut away design of the stove to see what is actually happening inside -- that would clarify some issues a bit. But in the end science will win, as to how much these stoves really act as a "mass" heater, as one also only needs to do the math (physics heat input versus radiation over time for mass M) to see these small stoves really will not radiate as much heat after the fire goes out that one may actually need (compared to a true mass heater -- which have a huge mass), which then really defeats the point of paying for a "mass" heater if the "mass" is insufficient to do an efficient hot fast burn, but in the end not heat the house enough.

Another indicator to me that these are more acting as minor radiant heater, or as a convective stoves was how both videos showed people touching the stove. A real small mass heater with a fire at that level would get actually very hot to the touch (I know because my neighbor has a real mass "small" mass heater which is even larger than the stove in these videos, and it can get very hot). But a convection stove would not get that hot, as the air flow cools the external casing. Case in point, a photo of my hand on my convection stove, which despite the pretty tile, is not in any way a mass heater.

2020-12-28 13.15.05.jpg

How much efficient these stoves are at doing other things, such as reducing particle pollution is another issue, but one that these stoves are pretty much required to report in their specs so that should be rather easy to check.
 
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qwee

Burning Hunk
Jan 17, 2013
134
Idaho
St. Coemgen thanks for the real world info. How does your neighbor with this small mass burner use it? Does he just keep feeding it wood (like a wood stove) when it gets cold?
 

begreen

Mooderator
Staff member
Nov 18, 2005
90,646
South Puget Sound, WA
I am having a hard time getting much info on the Norwegian Kleber Kube stoves. How are they constructed? Do they have internal smoke passages like a kachelofen or a basic stove with a soapstone body, similar to a Hearthsone soapstone stove? How much heat do they put out?
Can any of these stoves be bought or sold in the US?
 
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begreen

Mooderator
Staff member
Nov 18, 2005
90,646
South Puget Sound, WA
I think the mini masonry heaters only offer slight advantages over a regular woodstove. Similar to a soapstone woodstove vs cast iron vs steel and the convective vs radiant ideas. My cookstove is fairly light and made of inox and steel with lots of heat shielding for low clearances. As a result it is highly convective and can heat the whole house to 80 df but my wife might feel cold because she prefers the radiant heat of the Morso. This seems to be more of a preference thing. These big stationary masonry heaters only have one area of strong radiant heat, and that's the glass door. Elsewise it is several thousand pounds of masonry that is only slightly warmer than room temperature. Probably feels like heating from my wood cookstove vs using the Morso. Maybe some folks like that soft heat release from the warm masonry, many people in this country choose forced air despite my own opinions about it.
Cast iron jacketed steel stoves have a similar advantage. They are less radiant for closer clearances and the mass of the cast iron makes a notable reduction in room temperature swing throughout the burn cycle, much like soapstone.
 
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qwee

Burning Hunk
Jan 17, 2013
134
Idaho
They are made of soapstone outside, inside looks to be refractory cement. They said that they can be put up without the hi-temp cement so apparently anyone can put one together salesman said it took them 1 hour. But cement could be used if desired. The cubes look like they have a hole connecting each cube to the next. Usually the holes will be as far apart from one chamber to the next (so these are the gas passages. The rounded types are probably the same, just round instead of square. I don't know if they have tubes or combustors in them.

There is a dealer locator in the link - looks like 29 dealers in the US - 4 out west, Missoula, MT, Bend, Eugene, And Ashland, Oregon. I think there is a dealer in Alaska, too. Heat output probably depends on how you operate it - like a wood stove or traditional MH. Sounds like they are in the $5k starting range.
 
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begreen

Mooderator
Staff member
Nov 18, 2005
90,646
South Puget Sound, WA
There is a dealer locator in the link - looks like 29 dealers in the US - 4 out west, Missoula, MT, Bend, Eugene, And Ashland, Oregon. I think there is a dealer in Alaska, too. Heat output probably depends on how you operate it - like a wood stove or traditional MH. Sounds like they are in the $5k starting range.
I checked a couple dealers in our area. They don't list Kleber. I am wondering if this is because of the lack of EPA certification?
 

kennyp2339

Minister of Fire
Feb 16, 2014
6,119
07462
I love the idea of a masonry heater if you have a mid sized home with an open floor plan, while the practicality of them is excellent, the stone work to me is just beautiful and there an excellent focal point in a room.
 

qwee

Burning Hunk
Jan 17, 2013
134
Idaho
Also, these could be nice heaters in well insulated houses, or passive solar designs. Here is one being put together,
 

begreen

Mooderator
Staff member
Nov 18, 2005
90,646
South Puget Sound, WA
Looks like a splined stone construction, like a vertical Hearthstone with thicker walls. There is a bit of a labyrinth at the top, but this appears to be just hand placed with no spline or adhesive. Maybe it is held in place by the weight of the lid stone.
It's a good looker. What does this model sell for?
 
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qwee

Burning Hunk
Jan 17, 2013
134
Idaho
The cube 4 is around $6k - you can get little side glass panels which increases cost. That one being built must be a cube 1 (?).
 

begreen

Mooderator
Staff member
Nov 18, 2005
90,646
South Puget Sound, WA
Are they currently sold in the US given the 2020 regs?
 

SpaceBus

Minister of Fire
Nov 18, 2018
6,301
Downeast Maine
These mini masonry heaters are beautiful, but they seem limited to mild climates. In a really cold place I doubt those smaller fireboxes could keep up.
 

qwee

Burning Hunk
Jan 17, 2013
134
Idaho
Norway is cold. Maybe the houses are smaller or better insulated? Maybe it is how the burn them?
 

SpaceBus

Minister of Fire
Nov 18, 2018
6,301
Downeast Maine
Norway is cold. Maybe the houses are smaller or better insulated? Maybe it is how the burn them?
Norway is not all of Europe and perhaps there are more than one per home. The majority of Europe has mild weather and small housing, so the mass heater with a smaller firebox would be more popular.
 

EatenByLimestone

Minister of Fire
It would be interesting if the clad steel stoves had an option for uber thick castings. The PE T series could swing the trivits out for radiant benefit, and then the heavier castings could take over absorbing the heat for smaller spaces. The castings could be removed for ease of transport.


Eastern Europe doesnt have the reputation of a mild climate. The houses do appear smaller though.
 

SpaceBus

Minister of Fire
Nov 18, 2018
6,301
Downeast Maine
It would be interesting if the clad steel stoves had an option for uber thick castings. The PE T series could swing the trivits out for radiant benefit, and then the heavier castings could take over absorbing the heat for smaller spaces. The castings could be removed for ease of transport.


Eastern Europe doesnt have the reputation of a mild climate. The houses do appear smaller though.
Eastern Europe is also less densely populated and more mountainous. I think large mass heaters are the old version of high efficiency wood stoves, but they still lose heat to the earth through the massive footings they require. There's only so much heat in a pound of wood, and a firebox can only hold so much wood. With the proper insulation any stove designed to burn 40-60 lbs in one batch could heat a house all day using masonry mass or just heating the air within the house envelope. Seems like all of the larger forced air wood stoves have a firebox sized much like the large mass heaters and most folks run one or two fires a day in them depending on weather.

I like masonry heaters, but they are just like every other stove design, a subjective choice.
 

begreen

Mooderator
Staff member
Nov 18, 2005
90,646
South Puget Sound, WA
One problem with a large masonry heater in a milder climate is timing the fire right. The stove heats in 8-12 hr increments. If you start up the stove in the morning and in the afternoon the sun is streaming through the windows, it could get too warm inside with no way to throttle down the heat.
 
Sep 2, 2020
122
UP, Michigan, USA
Another issue with as masonry heaters not mentioned yet is where in the home one can be installed due to their weight. The larger units, and maybe many of the kits, need to be supported by a reinforced concrete slab at grade.

We were going to have one built for us in the house we recently moved into. We wanted it on the main floor, which has a basement under it. To make this work, we would need to cut a hole in the floor where the heater would sit, install steel posts onto the basement floor below, build a rebar and concrete pad on top of the posts so the pad is level with the floor where the heater will be installed. All that to support the weight.

We couldn’t afford the construction plus the cost of the heater.
 
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