|
|
Post by cedric on Jan 19, 2022 10:09:55 GMT -8
Hi, I'm building a batchbox 200mm (my third/fourth rocket build), and I want to use a glass door from an existing stove. Nearly all of the stoves I found have a door which is wider than it is tall, whereas the bactchrocket is taller than it is wide. Is there a very good reason I didn't think of that would prevent me from basically inverting the width and the height of the firebox, keeping the same volume ? Same size for the port, etc. peterberg, your insight would be very much appreciated...  Thanks ! |
|
serg247
Junior Member
The mountain can not be conquered, it can allow it to ascend...
Posts: 111 
|
Post by serg247 on Jan 19, 2022 12:25:41 GMT -8
In the works of engineer Sviyazev, the top of the door should be slightly lower than the top of the port.
|
|
|
|
Post by peterberg on Jan 19, 2022 12:43:07 GMT -8
As a matter of fact, the proportions came out of a year's time of experiments. The things that are of the utmost importance are: the height/width ratio of the port relative to the riser, the blind space of rear wall above the port (yes,truly!), the volume of the firebox relative to the riser, total height of the riser and diameter and other minor things like the placement of the air inlet, the shape and ratios of the p-channel or floor channel.
As you can see, the height of the firebox is firmly tied to the port and the space above it. Of course I tried the port all the way up to the ceiling which didn't work. A shorter and wider port didn't either. The only aspect that turned out to be not as stringent happened to be the depth of the firebox. A depth of 25% above the recommended values will have very little effect on the workings overall.
Lots of people asked me whether or not it would be possible to change the firebox' proportions. It's possible of course, people are entitled to do what they like. But be warned the chance of ending up with a dirty heater that refuses to draw properly as a bonus is extremely likely.
There's one exeption though: the DSR3 seems to be able to escape the strict proportions, presumably because the workings are different enough.
Alternative: try to find a door that's as high as the firebox opening. Cut the front bricks for the sidewalls of the firebox under a 45 degree radius so the very front opening is a better match for the width of the door. A square door is probably what you are looking for to achieve this.
|
|
|
|
Post by peterberg on Jan 19, 2022 12:45:29 GMT -8
In the works of engineer Sviyazev, the top of the door should be slightly lower than the top of the port. That's one (lazy in my opinion) way to avoid smoking out the front, yes. Mine is up to the firebox' ceiling and won't smoke into the room nevertheless. |
|
|
|
Post by firerob on Sept 29, 2023 1:11:58 GMT -8
As a matter of fact, the proportions came out of a year's time of experiments. The things that are of the utmost importance are: the height/width ratio of the port relative to the riser, the blind space of rear wall above the port (yes,truly!), the volume of the firebox relative to the riser, total height of the riser and diameter and other minor things like the placement of the air inlet, the shape and ratios of the p-channel or floor channel. As you can see, the height of the firebox is firmly tied to the port and the space above it. Of course I tried the port all the way up to the ceiling which didn't work. A shorter and wider port didn't either. The only aspect that turned out to be not as stringent happened to be the depth of the firebox. A depth of 25% above the recommended values will have very little effect on the workings overall. Lots of people asked me whether or not it would be possible to change the firebox' proportions. It's possible of course, people are entitled to do what they like. But be warned the chance of ending up with a dirty heater that refuses to draw properly as a bonus is extremely likely. There's one exeption though: the DSR3 seems to be able to escape the strict proportions, presumably because the workings are different enough. Alternative: try to find a door that's as high as the firebox opening. Cut the front bricks for the sidewalls of the firebox under a 45 degree radius so the very front opening is a better match for the width of the door. A square door is probably what you are looking for to achieve this.
Peter, you are saying that the height and width of the port are crucial dimensions and shouldn't be deviated from. What about the depth?
In our system the port's depth is recommended to 50mm. We have 60mm wide firebricks. Could we build the backwall from these? Which would mean a port depth of 20% above recommended value?
-rob
|
|
|
|
Post by peterberg on Sept 29, 2023 4:37:48 GMT -8
Peter, you are saying that the height and width of the port are crucial dimensions and shouldn't be deviated from. What about the depth? In our system the port's depth is recommended to 50mm. We have 60mm wide firebricks. Could we build the backwall from these? Which would mean a port depth of 20% above recommended value? Recommended value of the port's depth in the spreadsheet is a fixed figure. That should be different now, sorry for that. In general: The depth of the port should be no more than 1.5 times and no less than 0.5 times the width of it. A long time ago I tried one at twice the width which delivered results that were not as good. A port depth of 1.5 times the width didn't show the same problems. The theory is that the venturi is a temporarily restriction in the gas stream. Apparently, it won't work as well when the restriction is prolonged too much. In short: use the firebricks you have at hand and you will be fine. |
|
