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Masonry Heater

Started by stickframer, May 12, 2017, 10:11:17 PM

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stickframer

I was reading in Jack Sobon's How to Build a Classic Timber Frame House and had a few questions about masonry stoves.

1) Does anyone have one in their house and do you have a range there as well?
2) Can you make pizzas, pies, bread, etc. in the oven?
3) Publications where you could learn how to build one?
4) Could your standard mason build one?

Thank you  8)

Dave Shepard

I have seen Jack's in person. If you build an oven into one, then yes you can bake it cook pizzas in one. They do require some design experince, or good plans. They're may even be refractory kits that you could buy. Forno Bravo has a forum for bake ovens, but i don't know if they do masonry heaters.
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Brian_Weekley

I've researched them a little and considering one for a future house.  There are several companies that make kits and they don't look hard to assemble.  The only problem is that wife thinks that most of the finished masonry stoves are ugly (a lot of them are).  In my case, the key will be finding an external finish that she can live with.  The cook stove is a plus for her though.
e aho laula

stickframer

I really like the one Jakob used in Latvia from the Northmen Guild. It is wonderful, but way beyond my skillset. The finish on it is top notch.

red

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Don P

A friend had a crossfire precast unit that worked well and had a bake oven;
http://crossfirefireplaces.com/

Dave Shepard

I think Jack's is soapstone. Tulikivi is a big name in masonry heaters. They may have kits that could be installed by a mason. Every year in Jack's Hancock Shaker Village workshop there is a tour of a house he designed and built by a student that has a masonry heater with a built in bench with a cooktop on the kitchen end. In the spring and summer cooking usually provides enough heat. Brian, did you go on the tour to Ted's house?
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nativewolf

Quote from: red on May 13, 2017, 07:17:47 AM
Look at www.heatkit.com

This is a pretty well known one and then there is the masonry fireplace group
http://www.mha-net.org/

The'll tell you everything you need to know, links to masons in your area,etc.  I love the idea myself and will go this route instead of an OWB in any new home I get to build.
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loganworks2

Here is another possibility for a soapstone heater http://soapstone-woodstove.com/

Brian_Weekley

Quote from: Dave Shepard on May 13, 2017, 10:25:09 AM
Brian, did you go on the tour to Ted's house?

Dave, I looked through his album of photos.  Unfortunately, I wasn't able to go on his house tour because my wife had other plans and she had the car!
e aho laula

jimdad07

That's on my list to build as well.  The Masonry Heater Association has plans you can buy to build simple but functioning heaters complete with foundation requirements and materials lists.  Mine cost me $25 for the complete book of plans.
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jdonovan

1) own one, to be installed into my new house when it gets built, in the next +/- 6 months

2) kind of. The temperature isn't really adjustable like a normal oven. You put stuff in when its cooled enough, for what ever you are cooking. The mass of your stove determines how long it will hold temps. IMO they excel at high heat short cook (pizza) or low-n-slow (casseroles).

3/4
I opted for a Tulikivi, as I think they are the only UL listed masonry heater sold in the US. With insurance companies getting more risk adverse with wood heating appliances, I didn't want to get the house built and discover in a few years I couldn't insure it due to a non-listed fireplace.

All the tulikivi's are sold with installation, or they won't warranty the unit.

samandothers

Below was copied from the MHA site.

"Your masonry heater will burn virtually creosote free when using well seasoned (15 to 20 percent) dry wood of proper size. Only through your own neglect will you ever experience creosote buildup. If you discover creosote in your flue, immediately cease to use your present fuel. Have your chimney cleaned if heavy deposit has resulted and then use only well seasoned dry wood. For your own safety, remember only you can prevent a hazardous situation from developing.
DO NOT RELOAD IF MORE HEAT IS NEEDED IN A 24-HOUR CYCLE. WAIT 8 TO 12 HOURS THEN HAVE A SECOND FIRE, OR 3 FIRES IN A DAY – ONE EVERY 8 HOURS."

I think this would cause me to consider a wood stove or insert as I may desire a fire more often during a day.  Though I understand I may be wanting the aesthetics more than the heating value.

jdonovan

What samandothers has posted is a very important difference between any masonry heater and a metal stove.

Metal stoves, are, or can be continuously fired devices.
masonry heaters are batch burn

Think of a masonry heater as a battery. In the unit I have, you can burn 100lbs of wood in about 2-3 hours. For many stove users, thats a day of wood. It will be for me too. All that energy (well 80%), gets stored into the stone, and is then released over the next 24-36 hours.

You really need to learn your home, watch the weather forecast, and then decide how much wood you need to burn. Get it too wrong and you'll need a sweater, or an open window.

But the masonry stove is somewhat self-regulating. The rate of heating/cooling of an object is based on the temperature difference between the two objects, in this case, the room, and the fireplace.  Except for the few hours right after a burn, the surface of the fireplace is often only 110-130 degrees.

Take this example.

60 degree room 110 degree stove = 50 degree delta
75 degree room 110 degree stove = 35 degree delta

When the room is 60, the stove will radiate almost 40% more heat as when the room is 75 degrees.

As the room warms, and fireplace cools the heat output drops. Its kind of like having a big thermal flywheel in the house.



Brian_Weekley

I was told by someone who has one that you can burn pine in the masonry heaters because they burn so hot you don't deposit creosote like you do in an ordinary fireplace or woodstove.  For those that have one, do you find that to be true?
e aho laula

Dave Shepard

 Jack Sobon said he needs 70 pounds of dry wood for a burn. Doesn't really matter if it's hard of soft wood. It will go about 18  hours on a  charge.
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jdonovan

in a masonry heater you basically burn it wide open, hot and fast. So soft/hard does not matter much. Need more volume of the softwoods to get the same BTU's of hardwood. Also you generally split the wood smaller as you're not looking for a long fire.

Ianab

Quote from: Brian_Weekley on May 23, 2017, 06:19:39 PM
I was told by someone who has one that you can burn pine in the masonry heaters because they burn so hot you don't deposit creosote like you do in an ordinary fireplace or woodstove.  For those that have one, do you find that to be true?

Pine wont leave creosote if it's dry and you let it burn hot. The design of those stoves would make that more practical as you can run a good hot fire for a couple of hours, and store that heat for the rest of the night.

Pine etc will leave creosote if you try and damp the naturally hot and fast burning fire back to try and get a longer burn time. Or if it's green and fire is smokey.

Main problem with softwoods is they are less dense, so you need more cords of wood to get the same heat. So understandably most people would rather have one cord of Oak, vs 2 Cords of Pine. But if pine is easy to get, it's OK for firewood.
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jdonovan

Quote from: Ianab on May 23, 2017, 07:08:19 PM
But if pine is easy to get, it's OK for firewood.

on the east coast of the USA because it is a non-desirable firewood, its often free... but we all know the story about free logs.  8)

peterpaul

Here is our heater.  It is made of soapstone and granite.  More pics in my gallery. 





Mine has the bake oven and heated bench.  The oven can be either a white oven (heat comes from main firebox) or a black oven, (fire built directly in oven).

I burn mine with 10-12 agv. pieces of wood, 1-3 times/day.  After 6 yrs of operation, I have zero creosote build up in my chimney, fine white powder at most vacuumed out once per year.  I burn between 4-6 cords of mixed hardwood per year.  My house is large enough so I do not have to "open a window".

Regarding the appearance, a heater consists of a core and facade.  The facade (in mine at least) does not touch the core.  The facade can be anything, brick, stone, tile, plaster, etc. In Germany, I have seen heaters built into a wall between two rooms.  Each room had a different appearance.

The house that Dave mentioned has a brick facade, back oven and very large circular metal cooktops.

Mine has a temcast core.  http://www.tempcast.com/
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D L Bahler

In Switzerland, Southern Germany, and much of Austria there is a strong masonry heater tradition that derives from ancient sources, and predates the Roman settlement in the region.
There the oven is usually in this form: The firebox is in the kitchen, where it is a cook stove of varying complexity and sophistication depending on when and where the oven was built. It is built directly into the masonry wall that separates the Kitchen from the living area. The exhaust from the cook stove passes through a passage into the oven structure that is in the parlor. In Switzerland, this room is called the 'Stube' which is a word that denotes a heated room (the root word is the same as the English word stove). This oven has a snaked passageway or at the very least, the exhaust travels down the length of the oven some 4-6 feet, then turns around and goes back the other way) to absorb as much heat as possible. It's important that every straight passage of the exhaust has an access to clean it out.
Traditionally once the exhaust goes through the oven, it passes through the wall again into the kitchen, and just exits through a hole and vents into the kitchen. They used to either have a double-story kitchen with holes in the wall to vent the smoke outside, or had a small arched dome on top of the kitchen in the attic above to vent the smoke out there. In some regions (the areas settled by the Burgundians in the Late Roman era) they have a giant wooden hood over the kitchen with a wooden chimney that goes through the roof. These may all sound like unfavorable conditions, but remember that the proper chimney is a relatively modern invention.

The oven, like another pointed out, is built in 2 layers that are not connected together. The inner layer is of some material that can withstand extreme heat, and the outer layer is just any sort of masonry that can hold on to heat and preferably look nice. More modern Swiss stoves have a refractory masonry tile for the interior and a normal ceramic tile for the exterior. Older ovens are made of soapstone, sometimes solid soapstone with no double construction. Other stone like slate is sometimes used to for the exterior. 
Often time there is a very slat gap between the two layers which is filled with sand.

In the past, Swiss houses employed a small handful of floor plans that were all designed around the concept of the kitchen fed stove. The most common arrangement had 3 room stacked side-by-side with the kitchen in the middle, and a stove on both sides or only one stove and one heated room. Another arrangement had a wide kitchen at the rear of the house with two living rooms, a stove located near the center that fed ovens in both rooms.

The primary feature of these stoves is that note only do they have masonry fireboxes that absorb a great deal of heat, but long winding passages through which the smoke travels to absorb even more of it. They are very efficient. It takes a great deal of wood to fire them initially, but after that the wood used in cooking is generally enough to keep them heated.

In modern times, people have refurbished some of the old ovens by running steam lines through them connected to a boiler and a thermostat.
With the addition of an air circulation system, these ovens can be used as the primary heat source for an entire house. However, they will never work as well in that regard as a central forced air system. The room with the oven will always be warmer than the others.

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