|
Post by satamax on Dec 6, 2020 0:32:12 GMT -8
Hi everybody. On my big batch, permies.com/t/44806/Cobbling-workshop-heater-cooktop-oven i ran into two problems. I was overheating with direct heat. So i laid bricks under the oven. in the "barrel" But now it is a smidge too cold in the flat. I wanted to make another rocket in the flat. But don't see the point, as i waste heat. No my second bell is exhausting in the chimney, at about 160c° mid burn. I would like tap into the chimney, to add a small bench upstairs. Which would warm up the lounge. I wonder if with 160C°, may be 180C° at the top of the the second burn, i have enough left over heat to be of any use. Prior to the mod, i was at 120C° max at the chimney. The other two question i ask myself. How much ISA do i dare using? I'm already over Peter's recommendation. 11.2m² iirc. Of course, i will have a bypass. The third question is, how much heat this bell will shed. I have more than enough support. But the floor is wood. My idea so far, is to use air entrained concrete slabs underneath. But i want to make the outer casing out of apparent bricks. This has to be good looking. My bottom bell rarely goes over 65C°, for 4 tons. Here it will be far lighter. But about the same 20 cm thickness i guess. May be 12cm if i put the bricks on edge. And what do i do? Bell, or bench. It will have a bench shape anyway! Well, if anybody has an idea about any of this, i would be thankful.
|
|
|
Post by fiedia on Dec 18, 2020 6:46:52 GMT -8
Salut Satamax,
I am just working on a similar set up. My batch block is heating a second bell with 200°C smokes.
I had to remove the second skin, the heat was not sufficient to warm the outer skin. Presently, my exhaust pipe is 125mm diameter, the bell inner cross section 180x420, bricks thickness 60 mm. Bricks get warm on the upper 600mm, bellow, its quite cold.
Hope it helps.
|
|
|
Post by satamax on Dec 19, 2020 3:34:56 GMT -8
Ok, thanks a lot Fledia.
When you say the bell inner cross section is 180x420 You have one pipe on each 180mm side? Or it's implemented differently? IIRC, Peter said once, for a bell to perform as such, there should be 5 times the chimney size between inlet and exhaust.
Well, i'm set on a bell bench. And my chimney size is 200mm.
But i get your saying. Not too much mass. So it might be metal skin, covered by bricks. As the rest of the stove is made the same.
|
|
|
Post by fiedia on Dec 20, 2020 3:16:52 GMT -8
There is a detailed description of my bell here. I did some measurements with different distances between inlet and outlet. I remember that the optimum distance between them, was outlet 600mm lower than the inlet (I have a 125mmdiameter pipe). Setting the outlet lower did not heat much more the bell. But it is not a bench. with a low temp incoming smoke, you will have difficulties to heat a big mass. It is preferable to improve heat conduction through the skins, i.e. use a thin skin. I have removed the second skin of my bell since the incoming smoke is bellow 200°C. It does not smell up to now. May be with such a low temp, you do not need 2 skins.
|
|
|
Post by fiedia on Dec 27, 2020 8:10:01 GMT -8
satamax , I just edited this results for my two skins bell with low temp incoming smokes. Both skins in bricks (60 mm and 50 mm thick). Incoming smokes between 100 and 200 °C. Inner bell dimensions 1440 x 420 x 180 mm. Temp sensors at 240, 480, 720, 960, 1200 mm height. Hope it helps
|
|
|
Post by satamax on Dec 28, 2020 1:18:41 GMT -8
Cool, thanks a lot. The bell in and out clearly shows you're gathering heat. I need to find a metal skin!
|
|