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Post by josephcrawley on Dec 3, 2009 11:13:11 GMT -8
I finally finished my stove. It's a two bell stove made of bricks. The burn tube is made from 1 to 2 by volume clay vermiculite bricks. The mortar is 1 part clay to 3 parts sand. It is almost dry from firing it last night for a few hours and this morning for a few more. I'm not sure if it's going to heat the house but we'll see. Joseph www.flickr.com/photos/45224908@N03/4155473053/Fixed your link. Remember to place "url" (in square brackets) in front of and "/url " (in square brackets) behind all links. |
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Post by Donkey on Dec 3, 2009 17:28:58 GMT -8
Isn't it nice to finish something like this and have it work?  Well.... How does it work? |
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Post by josephcrawley on Dec 4, 2009 9:23:57 GMT -8
It's working okay. It hasn't gotten winter cold here yet but it will be tomorrow. I guess that will be the test. So far it does not make my house as warm as my cast iron stove but it keeps it warmer for a lot longer. Last night I fired it for about 6 hours it got up to about 58 in my 900 sq/ft house and this morning it had dropped to about 52. The main problem now is the amount of air leaks in the house. Maybe I'll fix those now.
I'm thinking of reducing the bell exit on the pipe side of the stove it is currently 2 x2 bricks in size and the top of bench gets plenty hot but the sides below the top barely warm up at all. If it was smaller it seems like that increase hot gas retention and get more heat. The flue temp is about 220 as it leaves the bench which seems like it could be lower.
Joseph
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Post by Donkey on Dec 4, 2009 18:27:28 GMT -8
You could also increase the height of the bench a little. I can't really tell from the image, but would one more brick in height make the bench uncomfortable? Also, if the chimney is just attached to the top of the bench, it can't be properly considered a second bell. For bells to work properly, they need BOTH the entrance and exit to be at the bottom. In this way, the hotter gasses will rise into the bell and only the relatively cooler stuff will exit. Instead of narrowing the opening (granted, I'm shooting from intuition without really knowing your layout), place a divider just behind the chimney that blocks the upper half of the bench. When flue gas passes through, only the relatively cooler stuff will then go down, then out the chimney. This should keep more heat inside the bench. If this is what you already meant, then sorry for the redundant rap.. carry on.  |
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Post by josephcrawley on Dec 6, 2009 12:01:42 GMT -8
Yeah it does have a divider on the chimney side. I could make the bench taller but then it would starty to cover those windows.
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Post by peterberg on Dec 6, 2009 13:19:17 GMT -8
Do you know what the temperature is in the chimney stack during a firing? With plenty of heat in the stack you could decide to enlarge the first bell. Preferably up to a point where the gases in the stack are somewhere between 100 and 150 degrees Fahrenheit.
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Post by josephcrawley on Dec 11, 2009 11:01:35 GMT -8
The stack temp is over 230 which is the max on my kitchen thermometer. I have been thinking of rebuilding the bench with the bricks laid flat instead of on edge which would double the mass of second bell and making the first bell a few bricks taller. It seems like bigger bells would be the only way to lower the flue temp, is this true? The house dropped to 39 this morning with an outdoor temp of 19. This isn't so bad considering that last winter a night like this would have dropped the house to closer to 32 but it still isn't all that good.
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Post by Donkey on Dec 11, 2009 13:01:46 GMT -8
Umm, let's see..
Bricks layed flat would provide more thermal mass, which hold more heat for longer. This is a good thing and might help with the 39 degree temps in the morning but it's not likely to solve your stack temp issue, which is about soaking up the heat before it gets there.
Solutions could be, better conductivity (which would be a different material, not brick and not practical), or larger surface area to take up the heat (in other words bigger bell(s)).
It might help a little to turn the bench into two bells by placing a baffle somewhere in there. This might raise the time (or distance) that each unit of heated air has to go before finding the exit. Seems to me that the baffle should be placed down the run so that the first bell (of the bench (really the second bell of the system)) would be larger than the second. This should help even out the heats of the two bells so that the fist won't be SO much hotter than the second.
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Post by josephcrawley on Dec 17, 2009 12:12:44 GMT -8
I have increased the size of the first bell by two more rows of bricks. It seems to radiate more heat since it has a larger surface area. I've also doubled the layer of stone on top of the bench to increase mass and because the stone closest to the first bell started cracking from the heat.
I have not taken a flue temp since this change. I had also thought about making the bench 2 separate bells. I'll give it a shot and let yall know.
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