bartl
New Member
Posts: 1
|
Post by bartl on Sept 6, 2020 1:59:16 GMT -8
Hello, I am making my design for a Batch Rocket heater. I want to use the batch rocket heater sizing spreadsheet as found on: batch rocket.eu. I just don't see where is the result as to what I need for capacity. I entered the values for Insulation factor, volume of the house and required difference; Yet I don't see anything as a result as how many kW I need, so that I can size my Batchrocket on that. Anyone who has another calculation tool for this that does work? Thanks for helping, Bart
|
|
|
Post by peterberg on Sept 6, 2020 7:35:01 GMT -8
Hi Bart, welcome to the boards. Maybe you missed something? The heat losses of the house (or room) to be heated. It's right under the required difference of temperature. Don't forget to hit the TAB key on your keyboard when all three yellow squares are filled in, otherwise the heat loss won't be calculated.
For example: insulation factor 0.5, volume of the room and open kitchen 150 m³ and required difference 25ºC like our house, heat losses 1.9 kW. Then just refer to the output power calculations to find a 150 mm system is required and two firings per 24 hours in worst conditions. In this example, the 150 mm system is already oversized, because we could revert to two double fires a day which will almost doubles the above 1.9 kW to 3.7 kW.
|
|
dcp
New Member
Posts: 35
|
Post by dcp on Sept 7, 2020 7:34:35 GMT -8
«Don't forget to hit the TAB key on your keyboard when all three yellow squares are filled in, otherwise the heat loss won't be calculated.» Any form that works with iPad?? Only Apple products home....
|
|
|
Post by peterberg on Sept 7, 2020 10:41:10 GMT -8
In that case, tick one of the other yellow boxes, tried it a minute ago and it works.
|
|
dcp
New Member
Posts: 35
|
Post by dcp on Sept 7, 2020 21:59:21 GMT -8
Thanks Peter Another question about size. About briks size , superwool and placement in a bell. I build a 200 mm rbb and right now I am at the riser mouth level with the outer bell. I used red briks 240/ 114/ 64 mm for bell ( 114 mm is the wall thiknes of the bell) and same size chamote briks for box & riser. I do have only this size chamote brick. Over the riser level I do plan to use red briks (with64 mm thikness on outer skin ) and chamote on inside allso 64 mm thick wall. My question : do I have to use superwool betwen the innerskin and outer skin of the bell. I have 13 mm thick superwool . Is 64 mm of chamote enough or do I have to use superwool? If I use superwool maybe it will be too much isolation with 64 mm chamote on inside. Or not?? Please advice. So many doubts on first build....
|
|
|
Post by peterberg on Sept 8, 2020 2:05:18 GMT -8
Dcp, it's not wise to leave the superwool out between a double skin. This is there to provide for an expansion gap, the bricks above the riser mouth are expanding quite a bit. For the same reason the skin is double above de riser, that's the hottest area of the bell. What you have there are bricks that are too thick for using on its side. I'd have that problem earlier and solved it. Have a look at the Brussels build on the website, there's a layer of bricks that are turned 90 degrees horizontally. That will give you room to place both skins with superwool in between. It's best to place the outer skin first, alined with the front you've already done. Then, place a wide strip of superwool all around inside, the height of say, two bricks on its side. Then place two rows of the inner skin out of firebrick on its side using refractory mortar, usually the same as the core has been done with. And then, repeat this process until you are at the required height.
Concerning insulation value of superwool: the insulation value of materials isn't absolute, it's depending on the temperature difference between hot and cold side. The higher the hot side, the easier the heat is transferred through. Moreover, firebricks are mass, insulation value of these are even lower than normal bricks. Don't worry, it works, this way there's more mass where the heater is hottest as well. I'd recommend to start the double skin a bit lower than the riser's mouth, say two layers of bricks.
|
|
dcp
New Member
Posts: 35
|
Post by dcp on Sept 8, 2020 5:56:00 GMT -8
Hello Peter. My dry stack is like this: imgshare.io/image/Ns69l7As you can see I am allready at the riser level Do you mean that will be ok? Why using Sairset on innerskin like on riser & box? I used Sairset E from HarbisonWalker International. They claym that Sairset will harden like ceramic after burning. Moovement with warm/ cold the bell will/will not crack the inner layer. Afraid of that I am thinking at clay mix. Clay/sand/wood ash mix will not hold?
|
|
|
Post by peterberg on Sept 8, 2020 6:34:07 GMT -8
As you can see I am allready at the riser level Do you mean that will be ok? As I see it, the layer that's placed transversely is already in the hot zone. I'd recommend you take off two layers and start with the turned layer from there. It's hard to break down your newly laid work, I know that all too well. It seems the 90º turned brick is cut shorter to fit the other two on top. That isn't necessary, the Brussels build looked quite good, much to my surprise. When plastered, it should be even better because the otherwise flat outside profile is broken up nicely by that horizontal ridge. Why using Sairset on innerskin like on riser & box? I used Sairset E from HarbisonWalker International. They claym that Sairset will harden like ceramic after burning. Moovement with warm/ cold the bell will/will not crack the inner layer. Afraid of that I am thinking at clay mix. Clay/sand/wood ash mix will not hold? If you are unsure to use Sairset in the upper bell part, why did you use it for the core then? That part will see much more movement during the heating/cooling cycle than anything else. Do you have Sairset at hand? Use that, as far as I know it's an air setting mortar especially suited to thin seams. You won't run into problems with such a construction. Cracking isn't an issue, bricks that are "walking" from their designated spot is, which could happen when using clay/sand mortar. In the picture there are other things to see: what about superwool insulation around the riser, this is your last chance to apply it? And the heater seems to be placed in a corner of the room. Is that wall incombustible, more specifically, built out of bricks? And if that's the case, I sincerely hope it isn't an outside wall. Concerning size: are you sure that bell is wide enough to suit a 200 mm core? A 200 mm system is a b****y big cannon, I know that by experience. Or maybe you are planning a bench as well?
|
|
dcp
New Member
Posts: 35
|
Post by dcp on Sept 8, 2020 8:41:40 GMT -8
Yes it breakes my heart but I will listen to you. I started in 28 july the building and slowly (after main job in the «second shift» & weekends) i manage to get here. but I will do it. I did cut the briks in that layer down to 14 cm from 24 cm. Reason: -2 skins of briks 64 mm + 13 mm superwool= 141 mm & the riser is so close to outer skin ( 5 cm back riser and 8 cm to the side)that for a hole brik is not enough place. the riser is so close because the core is 45 degrees in one corner of the bell. Thats why a sidewinder. imgshare.io/images/2020/09/08/F8B0AB19-3B82-480B-8E58-68167141BDFF.jpgIs the overall( more or less) view of my build. the height will be 2 meters. From the top riser under the top of bell wil be 0,6 meters distance. Topp bel is 0,4 meter under the ceiling of first floor the bell is 10 cm away from the brick walls. So I do have 5 walls of the bell wich wil be warming the house These walls are on the center of the house, those are some extensions/supports of the main chimney. that 0,3x0,3 m is the internal chimney. superwool I wil install now. in the first phase it will be only the bell. After the floor renovation the bench wil come too, on the other side of the chimney support. I have to moove the hole chitchen to make the bench. everythig will be in the center of the house. The house is a wooden house with 20 cm minerall wool isolation in the outside walls.
|
|
|
Post by peterberg on Sept 8, 2020 12:11:59 GMT -8
So the house is around the heater, which is very good.
|
|
dcp
New Member
Posts: 35
|
Post by dcp on Sept 8, 2020 23:37:58 GMT -8
I did watch the Schetchup for the Brussels oven and I am confused about 2 things in that build: -the height of the port is 330 mm while the size on batchrocket.eu is 317. Thats not so important as size tolerance? -box sizes do not match the ones on batchrocket.eu . those are bigger. Will my build perform ok ?? Will overheat the bell ??because the woodload is too big... only worries. I respected the sizes as in batchrocket.eu Hope I am not so cumbersom but really really have no experience in this field And if I do set the house on fire the insurance will not pay me a dime... Playing with fire in a wooden house....
|
|
dcp
New Member
Posts: 35
|
Post by dcp on Sept 8, 2020 23:43:43 GMT -8
So the house is around the heater, which is very good. [br Verry desirable at 63*57’59.99’’ North
|
|
dcp
New Member
Posts: 35
|
Post by dcp on Sept 9, 2020 0:16:19 GMT -8
Cracking isn't an issue, bricks that are "walking" from their designated spot is, which could happen when using clay/sand mortar.
Whille I read again your advice Peter I do ask: Sairset on innerskin & outerskin?? Only innerskin and clay mix on outerskin? Thanks for patience.
|
|
|
Post by peterberg on Sept 9, 2020 1:43:47 GMT -8
I did watch the Schetchup for the Brussels oven and I am confused about 2 things in that build: -the height of the port is 330 mm while the size on batchrocket.eu is 317. Thats not so important as size tolerance? I checked the drawing and you are right. The design is adjusted to the size of the bricks out of practical considerations. This way, the port is exactly 3 bricks high. Otherwise I would need a thin strip of 13 mm on top of the port. The deviation is a meager 4%, well within tolerances I would say. Firebox size is a little bit smaller than the numbers indicate, yes, for the same reason. Please stop worrying, as long as your build is close to the recommended values it'll work, no doubt about.
|
|
|
Post by peterberg on Sept 9, 2020 1:50:52 GMT -8
Whille I read again your advice Peter I do ask: Sairset on innerskin & outerskin?? Only innerskin and clay mix on outerskin? I'd say sairset on inner skin, outer skin the same mortar as the rest of the bell's walls. In case that mortar is a clay/sand mix you're fine with that. In fact, it's the same construction as the nice guys in Portugal are using. Since you are living that far north, is there a reason why you choose a partly single skin bell instead of a completely double skinned heater?
|
|