mushroom gatherers !
Attempting to add water heating to the challenges of using a Rocket
Two good interim projects would be to build a working solar hot water system, integrating that with the Radiant floor you wish to have, and second build a conventional R.M.H.-
creating a working model outdoors and proving the concept, before moving your 1st R.M.H. indoors !
To understand - in part - the tremendous amounts of energy you are trying to harness, 1st take a look at the Myth Busters Video's on exploding hot water heaters, You tube
has several copies ! Think the Boston Marathon bombings with more 2nd and third degree burns !
Please understand that there are many successful rocket mass heater Builders, more than a few here at Permies Rocket Stoves, Who have investigated adding Low Pressure
Boilers to a R.M.H., and have personally come to the conclusion that such a system would be extremely dangerous, and in any case mates poorly with even the best of the
newest designs of R.M.H.s !
While there are Two (2) new companies, soon to be three (3), who are offering kits to build conventional type R.M.H.s, none are offering any system of heating water beyond
putting a kettle on the top of the R.M.H.s barrel !
I can recommend going to cobcottage.com and downloading your PDF Copy $15.oo of Evan's and Jacksons Great book 'rocket mass heaters', there is STILL no other
book in any Language with as much rocket stove / Rocket Mass Heater Family Information ! ( and I don't make a Dime !)
Every time I get to this part of my post to a New member, and re-read what I have written and it is always more negative and opinionated (Bossy!) than I would wish, please do
continue to return to these pages so that someone can help you find a safer vision of your future that is still uniquely you !
For the Good of The Craft ! Think like Fire !, Flow like Gas !, Don't be the Marshmallow ! As always, your comments and Questions are solicited and Welcome ! BIG AL
First, if you want radiant floor, there's two solution. Either using it as a mass. Then, you'll need to digg a hole the size of your house, about 2' deep i'd say, insulate all that with PUR polyurethane boards. Then refill with earth, and put your exhaust pipes through it. Obviously you'll need a backhoe.
Or doing a hypocaust. There's two ways about the hypocaust. You will need the same kind of hole, depending on what kind of temps are outside, you could may be skip the insulation underneath due to convection. But still, you will need one on the perimeter. And as well, this time, an insulation which can cope with more heat. Like air entrained concrete, then you will need some piers, insulated from the ground. Above this, you make a floor out of concrete, , i can't see any beter material. Wood would char. Stone will need many piers, and will be hard to get airtight. Prestressed beams, and filler blocks. You will need to fill the filler blocks with concrete if you want the best heat transmission. Then pour a thin slab over all that. You could may be do this with earth. But then again, you need a backhoe. Tho, the mud you have dug can go above, to a certain extent and to hugelkultur beds too. Then you get your exhaust gasses through the huge bell chamber you have made. There's another thing about this. You might need an horizontal as well as a vertical flue pipe/chimney out of this bell, each being able to be closed when the other is open. As you could drag all the heat out of the fumes, and they won't go up a cold chimney. So you'd need at startup, a horizontal chimney going down even may be. So the whole system is beter on a hillside.
As for heating water with a rocket, it's been done. But is it worth the expense and risk. It can be made simple. But that tends to turn your house into a steam bath, and there's always the risk of legionella.
I think I will do it.
Miles Flansburg wrote:Matthew, here is a youtube to get you started!
As Satamax says, I will use the floor as the termal mass.
I have chosen pumice Stone for insulating under the flue Canals.
I have 1 question for this underground insulation: only under the pipes or also on the sides?
My idea is to NOT insulate the sides.
I imagine that the heat will heat a greater surface, and this is good.
I do not want a very hot line and then cold!
BUT, I guess that this heat will start to extend 1st on the sides, and then it will also expand downwards...
Is the best idea to insulate only underground but a much larger surface than the pipes?
I don't have the numbers for conduction, but i know it does exist. Tho, in the video, they haven't insulated the ground.
Heat doesn't go up. Hot gasses do. Heat radiates in all the directions the same, hence heat loss in the ground if you don't insulate.
I've done calcs with a 48 tons mass But it's the same for smaller ones. You need about 9cm of pur insulation. 8 might do, 10 is best to follow the RT regulations. Or 12 of XPS. IIRC you're in the cannarias? If yes, easiest one to get might be topox. Since it's spanish made.
Well, I just do not want to use polystyrene!
The pumice Stone is light (=insulates) and is not very expansive + local and natural.
Yes I understand that heat, in conduction, goes to all direction.
Only convexion is going up, I agree.
But there is a speed of conduction, which is not so fast.
... how fast?
Rocky underground is why I do not want to insulate so far from the pipes as digging ALL the house!
We dug it 60cm deep / 40cm large with electric pic...
So it might be worth loosing some heat...
1) If I insulate the bottom + sides of the duct, then the heat will go only upward = very Little radiant heat.
2) If I insulate only the bottom, the heat will go on the sides, great.
But on the sides, it will go up and down, everywhere, ok.
So, what is the conduction speed in stone?
Thus I will decide how large / far on each side of the pipes I should put pumice stone.
Ho, I think more...
Ok, there will be conducion in all directions, but some heat will be lost by the floor by radiation, which will occur only upward.
In conduction, is the heat going more and easier towards the colder places?
If yes, then I will loose not that much because the heat will direct more to the floor surface.
So this is also an useful information
Check if your type of stone is on the chart. The higher the number, the more heat you will waste.
But at least i can say, insulate the bottom as wide as you can. A daft idea, to use the benefits of convection, you could pipe a half barrel system, instead of normal pipes. Since the hot gasses go up, you would make a better use of the heat. It would take the heat more time to travel back down via conduction. And less need for insulation on the bottom. May be revert the half barrels, and cover them with some type of stones or pavers, so all the heat radiates mostly through the floor.
Satamax Antone wrote:A daft idea, to use the benefits of convection, you could pipe a half barrel system, instead of normal pipes.
Since the hot gasses go up, you would make a better use of the heat. It would take the heat more time to travel back down via conduction. And less need for insulation on the bottom. May be revert the half barrels, and cover them with some type of stones or pavers, so all the heat radiates mostly through the floor.
Sorry, I do not understand what you mean with a half barrel...