ionel
New Member
Posts: 19
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Post by ionel on Jan 5, 2017 12:08:54 GMT -8
Hi guys and gals.
I need some water heated (who doesn't?) and since heating water directly with a rocket is a no-no (think steam explosion), i'm thinking of something a little different. Let's say i build the core as usual and then i build the "mass". But i change the mass (let's consider a bell for this example) so that it heats up more than usual but not above 60-70 Celsius. In this mass i have some piping installed thru which water flows and takes some of the heat out for usage.
Of course, this bell's internal area and mass will be different since i'll be cooling it with water, but how much different ? It will be smaller, but how much. Or maybe not ? Should i keep heat in the dry mass or in the water ?
I need the water temperature to be in the 40-45 Celsius range, not more.
If someone has suggestion or has done this before, please hit me.
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Post by satamax on Jan 6, 2017 22:07:45 GMT -8
What do you need this water for? This would give a better understanding of the project.
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ionel
New Member
Posts: 19
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Post by ionel on Jan 7, 2017 2:50:18 GMT -8
A small part is for domestic usage (washing, showering) but the most part is for hydronic floor heating. I have plans for making a batch rocket heating 2-3 rooms together using a bench but this bench is not central to the house due to many factors. That means some parts of the rooms will be colder than others. Besides, when installing the floor (new house), putting hydronic tubing in is a good idea since they are cheap and don't require much work and if i need them later, they're already there. Better safe than sorry.
So i will install hydronic tubing anyway.
So, the only thing to consider now is how to heat water for the 2 scenarios above (domestic and hydronic). Domestic is mandatory, hydronic is optional. But if i can do domestic water heating, hydronic is just a supersizing.
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Post by matthewwalker on Jan 8, 2017 5:57:27 GMT -8
I suspect you'll be disappointed with the performance. It takes a lot of power to heat water. Look at Tim Barker's and Donkey's rocket water heaters and see if you can fit something along those lines into your design if hot water is a primary goal of your build.
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ionel
New Member
Posts: 19
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Post by ionel on Jan 9, 2017 5:41:54 GMT -8
Thanks.
I've read them both, in depth this time. So, a throw out guess is that heat transfer efficiency from fire to water is ~ 20%. Mighty low but at least the burn is clean.
Well, at least one could use the rest of the heat to warm some small bell / bench so it's not lost.
It seems the simplest form, and the least efficient, is to use a stainless boiler tank to capture fire heat. Using gas boiler's HX might improve transfer efficiency, but by how much ?
Capturing whatever exhaust heat remains in a bench with some copper coils in it to preheat incoming cold water might increase efficiency.
Or, maybe the best option, since efficiency is so low, would be to combine water heating with space heating, basically robbing a little of space heat for water heating.
Lots to ponder ...
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serg247
Junior Member
The mountain can not be conquered, it can allow it to ascend...
Posts: 111
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Post by serg247 on Jan 9, 2017 6:13:38 GMT -8
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ionel
New Member
Posts: 19
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Post by ionel on Jan 9, 2017 6:41:34 GMT -8
Hi Serg.
My Russian Fu is quite weak in this part of my life and although i can read Cyrillic no problem, it's the "russian" written in it i'm having troubles with ... The pictures don't offer enough detail (unless i register) to figure out what's going on.
Might give a short description, maybe a clue to what pages are more relevant ?
Thanks.
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serg247
Junior Member
The mountain can not be conquered, it can allow it to ascend...
Posts: 111
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Post by serg247 on Jan 9, 2017 7:09:07 GMT -8
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Post by drooster on Jan 9, 2017 9:29:08 GMT -8
Ionel just wants to heat some water. The very complicated Russian link from Serg seems way over the top, but of course definitely worth discussing. (His refractory castings and material are, in my opinion, far more interesting than the actual stove/water setup.) I know I read a good old thread with a big metal bell and water jacket ... but that was ages ago and I can't point to the link. Sorry.
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ionel
New Member
Posts: 19
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Post by ionel on Jan 10, 2017 2:47:32 GMT -8
Thanks for the links.
Now, i don't necessarily just want to heat some water. If due to costs / material availability / personal technical manufacturing ability / time / etc., i will have to build the low efficiency heater (stainless tank from an electric boiler), then i would be very happy to build a slightly larger rocket which will be 20% water heating and the rest of the energy will heat the space.
What i could see in the russian heater was a very large surface area between hot gasses and water. As mkrepel said in the respective thread, that should make a very efficient water heater because more energy goes from hot gasses to water. I haven't seen the details of how the exchanger is built and if my actual skills can accomplish that. I will dig again thru the russian site and see if i can make something of it.
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Post by moheat on Feb 26, 2017 8:23:27 GMT -8
Does anyone understand what is going on with this rocket boiler?
It seems a person could use a rocket core like this to heat a volume of water to for a hot water radiant system in a floor or a wall. A way to utilize the rocket core into a central heat system.
I have some experience with gas fired boilers doing the same thing and they do better when allowed to "idle" or run constantly such that there is a constant put and take of heat into the system. When it gets behind, it cranks up, brings the temp up, the resumes the idle.
That would require a constant flow or feed system. His pellet feed is a form of that.
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fiskfarm
New Member
Hey fellow woodnuts. Been building what we now call "gasification" wood stoves since the 70's.
Posts: 3
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Post by fiskfarm on Feb 27, 2017 10:06:15 GMT -8
I heat a 330g IBC to 150F which sits on a stand for a better thermosiphon from the "boiler" chamber of the stove. I then placed an @ 8' loop of 1" copper inside the IBC which cycles with our 50g DHW tank 40' away. I use a differential T-stat that turns on a small 12v "solar" circulator whenever the coil in the IBC is hotter than the DHW tank. 3rd season and doing great. My RMH design is a bit different and based upon many builds I have done starting in the 70's when many of us could not afford oil heat nor a commercial wood stove. (remember the Jimmy C. days). The heat exchanger is a 6.5" SS pipe welded in the center of a 55g drum and that water circulates to the IBC. This season I made and inserted a "Turbulator" inside the SS flue pipe for better heat transfer. It takes about 24hrs to heat the IBC to 140F. I have automatic controls that turn on the radiators (overriding the room t-stats) when the IBC hits 150F. Anyhow and fwiw here are some pics: Well my vid links work but not my pics so bear with me. Perhaps not "shared" right. Nope, I give up. No pics. Sorry. Out of time. Can't seem to get the links shared on this forum. Even when I try a 100kb attachment it says I am over the 1MB limit?? Blue flames in rocket chamber Build
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fiskfarm
New Member
Hey fellow woodnuts. Been building what we now call "gasification" wood stoves since the 70's.
Posts: 3
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Post by fiskfarm on Feb 27, 2017 11:31:13 GMT -8
No luck with simple pics.
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