Firewood Questions

[Redneck in training]

In the old days every village house used to have brick oven. It was only heat in the whole house. It was used for cooking, baking and also sleeping. Especially in the winter. The flue gases from the oven meandered trough massive brick structure, heating it up, before exiting to the chimney. Since it was used for cooking year around there was bypass flap allowing flue gases passing directly to the chimney when heat was not desirable. When children misbehaved they were told to shape up or won't be allowed to sleep on the oven.

Affluent houses used to fancy ceramic stoves. Here is a link to few pictures
Fotogalerie firmy Keramická dílna Prudký-hladil - Kamna/DSCF0027
?eský kamná? | kachlové sporáky | výhody, nevýhody, materiály, kamna s vým?níkem, akumula?ní kamna, krbové vlo?ky, krby teplovzdu?né
There are probably hundreds of brick ovens and ceramic stoves builders in the Czech Republic.

 

[ultrarunner]

The temps are higher, people are very conscientious as to using seasoned wood and each gallery has a removable tile access for cleaning...

I will have to look for pictures...

 

[Little_Grizzly]

I don't know about different wood species in different areas but out here where I am in California, the oak I have to split (live, white, blue, etc) can NOT be split when green. You hit it with a maul and it will bounce right back at your head. I "fell in the fall and split in the spring" Right when cracks just start to appear in the cut logs then you can split it. Let it dry out completely and again you can't split it at all. Heck, you can barely cut it. I've seen sparks coming off my chainsaw with dry oak! :laughing:

 

[clemsonfor]

Chainsaws spark in green wood. Go cut something in the dark. Its the chain running through that channel at hundreds of rpms that causes sparks. Th dry wood just dosent help as it dosent cool it and wet it.

 

[jnelson]

Wont that thing choke up in creosote if it winds that much cooling off as it goes?

The others are correct that the fires in a masonry stove are built using very well seasoned wood and are not damped but rather are allowed to burn very fast and hot. Creosote is unburned wood byproducts produced by incomplete combustion. Complete combustion of the wood in the firebox results in no creosote to condense on cooler chimney walls. From what I have read the masonry stove chimney walls remain very clean in spite of the fact that they meander around and travel long distances before venting to the outdoors. I've also read that they frequently are designed with a shortcut bypass which is opened to let the fire catch and create a draft and then shut once the fire is drawing well.

The concept behind masonry stoves is that the wood is burned very fast and hot (usually fires last about an hour) extracting maximum heat from the wood burned and storing it in the large mass surrounding the chimney channels. Once the fire is out the chimney and/or combustion makeup air vent are closed to stop the draft and trap the heat in the stove mass where it is given off by radiation slowly and evenly throughout the day.

If you search masonry stoves, Russian stoves, ceramic stoves, etc on the Internet you will find lots of interesting articles about the subject. It sure makes you think about how inefficient our methods of heating with wood are.

JN

 

[EE_Bota]

The others are correct that the fires in a masonry stove are built using very well seasoned wood and are not damped but rather are allowed to burn very fast and hot. Creosote is unburned wood byproducts produced by incomplete combustion. Complete combustion of the wood in the firebox results in no creosote to condense on cooler chimney walls. From what I have read the masonry stove chimney walls remain very clean in spite of the fact that they meander around and travel long distances before venting to the outdoors. I've also read that they frequently are designed with a shortcut bypass which is opened to let the fire catch and create a draft and then shut once the fire is drawing well.

The concept behind masonry stoves is that the wood is burned very fast and hot (usually fires last about an hour) extracting maximum heat from the wood burned and storing it in the large mass surrounding the chimney channels. Once the fire is out the chimney and/or combustion makeup air vent are closed to stop the draft and trap the heat in the stove mass where it is given off by radiation slowly and evenly throughout the day.

If you search masonry stoves, Russian stoves, ceramic stoves, etc on the Internet you will find lots of interesting articles about the subject. It sure makes you think about how inefficient our methods of heating with wood are.

JN

Is the ultimate efficiency known? The modern EPA stoves here in the US are rated higher than 70% efficiency. I wonder how much better the ceramics do?

I have this stove, and they rate it at 75% efficient. But what does that actually mean? I really don't know...but except for the front, the walls, top, bottom, back are all soapstone. The front is supposed to radiate quickly to give you some immediate heat, but the rest is very slow to heat up, but does stay hot for a good long time. But, the only rating of the Russian or Finnish stove I have found said it was 90% "combustion efficiency." What does THAT mean? Are we talking apples to apples here, or is the stove really 15% more efficient, or even more that the soapstone stove I use?

http://www.hearthstonestoves.com/wood-stoves/stove-details?product_id=20

I read for the ceramics, etc, they start two short fires per day mostly, and then close off the damper completely when the fire is burned out so the heat cannot leave the chimney. I read the the only downside is that you have to anticipate the need for heat, since you will not get that heat quickly, nor will you be able to stop heating quickly should the heat not be needed.

I would love to have a ceramic, at least to try, but people in the US need to realize, if they do not already, that the stoves here are ~50% more efficient that in the past, and that can make a big difference...for those who are not ready to build a Russian stove of their own.


Ok, a bit more...this site claims at the bottom that the EPA efficiency includes combustion efficiency and heat extraction efficiency combined.

http://www.chimneysweeponline.com/wscompe.htm

 

[DAY]

Regarding masonry stoves, think of putting a candle under a brick, and letting it burn until the brick gets hot- which it WILL, but only after a lot of wax turns into soot!
Then put a propane torch under the brick- it will also get hot- in a HURRY! That is the concept behind the masonry stove.
But, as others have said, retro-fitting a house is not easy, just as adding insulation is harder than putting it in when the building is going up.

That said, every little bit helps, and weather stripping gives the biggest bang for the buck, no matter if you heat with wood, oil, or electric.

And turn of the dang lights!

 

[ultrarunner]

I read the the only downside is that you have to anticipate the need for heat, since you will not get that heat quickly, nor will you be able to stop heating quickly should the heat not be needed.

Yes, it can be an issue when someone is not at home on a regular basis.

Had friends come for a visit and we arrived at the cabin at the same time in the middle of January with 2 feet of snow outside...

They told me to crank up the heater which I did... it took about 6 hours for the place to start warming up...

Another thing from the same visit... everyone wanted to go to the city for the day and stay out late... getting home at midnight meant that the first thing I had to do was build a fire and then wait about an hour for the flames to become coals before closing the fire box.

Leaving the fire box open lets all the heat draft out through the chimney and closing the box too early can crack the tiles... or put the fire out.

It definitely is a compromise for someone used bumping up a thermostat and be done with it.

There are automatic dampers that can close off the fire box at the right time...

The radiant heat is wonderful and having a bench with your back to the stove tiles in the middle of winter is luxury... also none of the tiles ever gets hot enough to present a safety hazard for children...

One of my cousins has one with a built-in bread oven and glass fire doors... very nice... spent about $7,000 for it installed.

 

[ultrarunner]

Here's a link for the brand my cousin had installed...

Biofire Technical Info

These stoves are 90% efficient and the design goes back many hundreds of years... even Mark Twain wrote about them...

Here's one more link from an Oregon company...

http://www.kachelofen-usa.com/

Forgot to mention on the oven I did was the fire box door is over the cement stairs to the cellar... so the wood never comes into the living area of the house and no bending down to load the fire box... still looking for a picture to post...

And one more from the State of MO in PDF form on how to build one variation

http://www.dnr.mo.gov/pubs/pub781.pdf

 

[DAY]

These stoves are not for everyone- remember, they were built by European farm folk, who rarely strayed far from home. In 19th C. America the cast iron cook stove was the main source of heat for the farmhouse, and was hot 24/7. In warmer weather the cooking was done in the Summer Kitchen- a separate building.