panos
New Member
Posts: 9
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Post by panos on Feb 18, 2017 14:34:44 GMT -8
I want to build a batch box heater 150mm heat riser diameter. The dimensions of the firebricks in my area are 22x11x6 cm. So for example if i stack vertically 3 firebricks for the firebox it gives a height of 33 cm instead of 32,4 cm as mentioned in the spreasheet's dimensions for the 150 mm system. Now in this case should i cut the firebrick so that it matches exactly to the 32,4 cm height? Or should i scale down the initial system to perhaps 145mm diameter for the heat rise so it fits better?
Would a straight firebrick core be sufficient for heating a small house(not good insulation but it is just a house of 48m2/3 rooms)? My floor is tile. I can't build the firebox on top of it.Right? Do i need to put an additional layer of firebricks as a base for the firebox? Do i need to put any other insulation to the floor?
Last question is how much clearance should be between the firebox or the bell and the wall? How many cm of insulation of perlite do i need to put all around the hot firebox?
Thank you for any help! Btw my location is Greece and it is the first time we had such a cold winter in January.Totally not prepared for this,and as for the traditional fireplaces they are a waste of wood for the most part.It actually costs like 2000 euros to have someone build a fireplace in a new constructed home.
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Post by peterberg on Feb 19, 2017 5:06:43 GMT -8
I want to build a batch box heater 150mm heat riser diameter. The dimensions of the firebricks in my area are 22x11x6 cm. So for example if i stack vertically 3 firebricks for the firebox it gives a height of 33 cm instead of 32,4 cm as mentioned in the spreasheet's dimensions for the 150 mm system. Now in this case should i cut the firebrick so that it matches exactly to the 32,4 cm height? Or should i scale down the initial system to perhaps 145mm diameter for the heat rise so it fits better? Hi Panos, welcome to the boards. The easiest way to build is this: take the pattern of the drawing and arrange your bricks accordingly. Most of the figures are OK with some tolerance up and down, they aren't exact. Would a straight firebrick core be sufficient for heating a small house(not good insulation but it is just a house of 48m2/3 rooms)? My floor is tile. I can't build the firebox on top of it.Right? Do i need to put an additional layer of firebricks as a base for the firebox? Do i need to put any other insulation to the floor? Hard to say whether your house can be heated with such a system, depends on a lot of factors like wind, orientation to the sun, average winter temperature, how large the windows are and so on. Try the calculator of Yasin Gach, see batchrocket.eu/en/building#size. What is under the tile? You could lift the firebox off the floor one way or the other. Laying firebricks on the floor and building on that isn't enough, you need to have some air space beneath it. Insulation is good, but airspace is mandatory when you don't trust the heat resistance of the floor. Last question is how much clearance should be between the firebox or the bell and the wall? How many cm of insulation of perlite do i need to put all around the hot firebox? The firebox will get awfully hot, please don't place that close to a wall. In a brick bell would be OK provided it isn't thin. When the wall is uncombustible, about 10 cm distance from the bell would be good. Wood frame walls are different, take 20 cm and an aluminium radiation shield between wall and bell. The firebox could be left un-insulated when it's completely inside a bell, the riser do need insulation however. About 5 cm of perlite with a little bit of clay and just moist enough to get it stabilized when the clay dries.
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panos
New Member
Posts: 9
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Post by panos on Feb 19, 2017 7:57:04 GMT -8
Thank you very much for the response. Under the tile there is cement.
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Post by gugaiz on Feb 20, 2017 5:52:33 GMT -8
........ the riser do need insulation however. About 5 cm of perlite with a little bit of clay and just moist enough to get it stabilized when the clay dries. Hi Peter, when you say clay, you mean normal clay (the red one for pottery) or fireclay?. I am in Argentina and can easily get clay but if fireclay is the right material, then it is harder because what I found here is what they call "refractory earth" which is basically the material they use to make refractory bricks but does not bind as clay does. I also have another question... which is the max expected temperature inside the heat riser for a 8" system? Could it be 1000°C? I have found expanded perlite in half rods as material for the heat riser, but it only support 650°C Thanks!
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Post by peterberg on Feb 20, 2017 7:07:19 GMT -8
Pottery clay would be perfectly adequate.
I am afraid this material isn't the right one... Highest temperature measured in a 6" batchrocket riser happened to be 1173º C, waaay more than the perlite can handle. Normal temperature at the hottest spot is 1100º C, easily.
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Post by gugaiz on Feb 20, 2017 12:26:18 GMT -8
Great, thanks for the answer, but then... why perlite with clay will work but not perlite alone?
The perlite we are talking about is the one used for gardening isn't it? which are little rocks instead of powder.
Is there a post/place where I can read about this technique and proportions? I can't find it.
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Post by peterberg on Feb 20, 2017 12:42:30 GMT -8
The perlite/clay is meant to be an insulation layer around the refractory material of the riser. This perlite material is not suitable for the riser itself, for reasons I mentioned above.
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Post by gugaiz on Feb 25, 2017 17:15:10 GMT -8
I have found that matthew walker did a mix with fireclay/perlite. Do you think that this mix will work for the heat riser without the need of an extra refractory material?
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