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Bench going up and down, how many feet do I substract?  RSS feed

 
pollinator
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I enjoy the new book, it is great and precise!

This is not recommended to do up and down zig-zag, but this topic is not fully dealed about.
I would do just one, not more!
I plan a heated floor, but hesitate to go up, and then down, for a warm bench also.

It would be very close to the RMH and would go up from beneath floor level + the regular size for a normal bench, and then go under-floor again.

I have read about the way to calculate all what is slowing down the draft, such as unsmooth duct and corners.
Has it been calculated what up and downs are taking from the system?

Thanks
 
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I wonder if instead of running the duct up into the bench then down back under the floor, you could make that entire area into a bell instead. Hopefully someone can provide some input on the idea.
 
gardener
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In terms of friction loss, elbows are elbows, whether they are horizontal or vertical. You are talking about four elbows here, so I second the idea of looking into making a bell at the bench location. It would probably have about the same loss as if it were straight duct, considering entrance/exit transition losses (minimal), and would give considerably more heat exchange surface. Just be careful of too much heat exchange so you don't rob your system of all final draft at the chimney.
 
pollinator
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Xisca : We have talked before and i think my image of your problem may be a little clearer than David and Glenn. Xisca am I using the right word
for the natural volcanic material that makes up your house I believe you called it 'Tuffs'

Don't think Cave, Xisca's house site is older than most towns in the Americas!

As I understand this is denser and harder than pumice and some what workable ! Due to low ceilings(!), channels for the pipes must go down ! We
are talking about Shallow angles of slope and not 90º Bends !

Xisca, I am more worried about every time you jog up you will be creating a hot spot, with planing and care you can move it several feet to one side
or the other !

I do not have an answer for you, I think you will have to try several combinations of angles and accept that getting This done will be a lengthier
process than you hoped !

Anyone else able to help on this unique RMH installation ! For the Good of the Craft ! Big AL
 
Xisca Nicolas
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Thanks, I did think about a bell, but thought my idea was stupid!
So double thanks....

Glenn Herbert wrote:In terms of friction loss, elbows are elbows, whether they are horizontal or vertical.


And the loss of going up and down?
Isn't it MORE than "only" elbows?
Turn + flues going DOWN.

About the bell... YES PLEASE, I did not see it in the book.
Is the dict just the same level at the bottom, and increased up the the necessary hight in the bench?
I just want a little 2 persons bench for a warm breakfast...

I LOOK WITH THE SEARCH, and if necessary I make a new topic for BENCH BELL.

I still think it would be useful to include this in the book, about the loss of draft when going down.
.
.
.

Special news for the ones who read me before:
Al, I make the RMH at the entrance part, so I have solved many problems, and only 1 side of the bell will be near the rock.
My cliff is not pumice type,
but I did find some of this light stone, for the insulation UNDER the gases ducts.

I have solved also the chimney problem. It will be 15 feet high, between 4 and 5 meters, in stone, to hide the 8" pipe.
Super insulation, as this chimney will be behind the pilar I finally had to do for maintaining a dangerous rock that could fall.
When I will start the topic with design and pics, it will be clearer why the design was soooooo difficult.

I keep the 8" design for the size of the fire (it will be at floor level and visible from above)
though I am subtropical.
 
Glenn Herbert
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The basic criterion for a bell is that is large enough that the gases do not "flow" in a line, but stratify and let the hottest part rise to the top by itself. This translates to a minimum of four times the system size, so for an 8" system, a 16" diameter (4x the area) or equivalent would be called for. It could be say 12" wide x 16-20" high x the bench length. It will have more internal surface area to absorb heat than the same length of duct, so you should figure that into your run.
 
Xisca Nicolas
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Thanks Glenn, I had read this in an post from Peter VDB, and I had understood 4 times wider, which would be very wide for a bench.
So this is 4 times the CSA...

I have another option!

I want a warm bench in the morning for breakfast.
And make a firre in the evening.
So if I build my warm floor, I can build a bench without the pipes going up. If the heat goes up in 9 hours, then it will be ok for the morning.
I am making plans about the insulation and conduction, for the diffenrent parts.

And easier than building a bell!
 
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Nicolas, have you seen this one?

http://donkey32.proboards.com/post/14109/thread
 
Xisca Nicolas
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Superbe Max, mais un peu haut pour un banc haha!

That's very nice though the "bench" is a little high for butt's warming in the morning!
I keep this sort of design for later on....
I have do do more than one stove at my place...
What is great is that I noticed that the down draft after the riser can be in a pipe instead of around the riser!

 
Satamax Antone
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Xisca Nicolas wrote:Superbe Max, mais un peu haut pour un banc haha!

That's very nice though the "bench" is a little high for butt's warming in the morning!
I keep this sort of design for later on....
I have do do more than one stove at my place...
What is great is that I noticed that the down draft after the riser can be in a pipe instead of around the riser!

Yes it's possible, but you're trying to fight against convection, so you need a better draft from your chimney, which means leaving more heat to escape.

T'est Français ?

 
Xisca Nicolas
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Et même française....

The problem about convexion comes only from the fact of not using metal but massonry, IMO.
the fact that that down draft goes into 1 pipe instead of all around the heat riser looks to me more of suppressing the radiation of the oil drum, don't you think so?
 
Satamax Antone
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Désolé ma belle.

Donc, c'est Bien Xisca, et pas Nicolas Mille fois désolé (sorry guys! you can always use google translate! )

Yep, there's a rapid cooling of the gases in contact with the barrel, but i'm not sure it creates enough advection movement to oppose to the convection.

It's all about temp differential and presure differential. But even if the cooled down gases have a highger density than the hot ones, they're still lighter than the ambient air at both ends of the system.

I have been wondering about that suposed downdraft pump effect in the barrel for a while.

I think the best answer is, when you put a barrel around a test rocket, always the draft suffers. Even tho the whole bottom is open. The gases are nowhere like nearing the dew point, nor cooling more than ambient, which would be necessary to create a draft.

All it might do is impede less the draft created by the heat riser than if the gases were hotter.

Well, hth.
 
Xisca Nicolas
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You are forgiven...

Satamax Antone wrote:I have been wondering about that suposed downdraft pump effect in the barrel for a while.

I think the best answer is, when you put a barrel around a test rocket, always the draft suffers. Even tho the whole bottom is open. The gases are nowhere like nearing the dew point, nor cooling more than ambient, which would be necessary to create a draft.



I do not understand, and it does not matter the language!

I do not think the barrel is making the draft, and I agree it impedes it!
But that's the way to make the gases go another way than their natural one (which is up!)

So if you want the gases to go down and then horizontal, the metal barrel is helping it more than a masonry.
I understand this of the temperature differences, but I did not think about the pressure... That is may be why I do not understand you so well...
 
Satamax Antone
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Well, everybody says heat goes up!


Nope, heat travels in solids in all the directions at the same pace.

It's different in fluids.

Heat shake the atoms, which in turn take more space than if they were colder, thus making the material less dense. And that less dense material is pushed up by heavier material.

Would it be water, oil, gases, molten lava etc!

Heavier air is denser, so it exerts more presure than hoter less dense air. Which makes density and presure linked. And heat as well, because it makes materials less dense. (not absolutely sure it's the case for all, like water, if it freezes it's less dense than liquid water, but if water is hot it's less dense too!)
 
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