Help! My Rocket doesn't heat

[cedro]

This summer I built a Rocket that also heats hot water with the aim of heating my house. Now that winter is coming I have started using it, but I am not satisfied with the performance. I will try to explain the typology of the house and the Rocket

House: divided into 2 floors, lower floor about 30m2 and upper floor 45m² for a total volume of about 170m³. The house has 50 cm thick stone walls, the windows are old with drafts. In winter the temperatures can reach around 0C.

Rocket: 21 cm style in refractory bricks with the riser not insulated. The barrel with the j is on the lower floor while the heated bench (mass) is on the upper floor. In the space between the barrel and the riser there is a copper coil (outer diameter of the tube 10mm, total length of the coil 40m) that heats a 500l water accumulation, to this accumulation are connected the radiators that heat the rooms on the upper floor where the mass is not located.

Circular chimney of 18 cm high 7 m that comes out at the highest point of the roof I use chestnut wood of various diameters from 5 to 15cm, dried correctly

Current situation: after a burn of about 5 HOURS at full load (so much so that sometimes the fire goes up the sticks), boiling barrel and bench, water accumulation temperature increased by just over 40 degrees from 20 to 60, I turn on the 3 radiators and use the water for a shower, in the house there are about 20 degrees with an outside temperature of 13 degrees. After 8 hours from turning off, cold bench, warm barrel, water in the accumulation at 35 or too cold to circulate in the radiators. I wonder why I have to do such prolonged ignitions (I use a lot of wood) and after 8 hours everything is already cold!!! Where am I going wrong? Undersized machine? Coil does not absorb enough heat

Another thing, as soon as I finished the work I tried the Rocket, in a few hours the water in the accumulation had reached 80 C°, why can't I get this great performance anymore? Was the mass humid, were the internal surfaces smooth? Wasn't the coil dirty?

I attach photos and drawings
drive.google.com/drive/folders/1PbEUrD4bh04r1a_BSedy0mlV4zeP_zZn

[Dan (Upstate NY, USA)]

I can't answer all of your questions.

But one answer stems from where is you water coming from?

I am on ground water and city water.

My well water is 58F in the summer, 50F in the winter.

My city water is 65F in the summer and as cold as 35F in the winter.

Why? The city water runs in pipes less shallow, 5 foot deep, right at the edge of the frost line on some weeks...

In the summer I run almost max cold with my hot, in the winter I run half and half cause the shower is on city water.

[Dan (Upstate NY, USA)]

My second answer is the stone wall, if that is adjacent to earth then it is an infinite heat sink, to raise the temperature of the earth around the house 10 feet out is going to take an amazing amount of BTUs and once you get it warm it will quickly fade within a week.

That's why modern builders put spray foam down, then pour concrete floors to isolate the mass from the infinite heat sink of earth at 55F.

[thesolution]

Cedro, the riser has to be absolutely sealed, otherwise no draw, no draw no heat. The riser is like the heart in your chest. it is everything. You said you used bricks, oh boy, lots of angles, plenty leak areas. If you did use cement to seal them, but made a hot fire before the cement cured, there could be many hairline cracks as the moisture turns to steam.
   
  Some years ago a lady on YouTube made a beautiful mass heater, nice couch/mass, the works. One day upon cruising the web I see her taking the whole thing apart because she said it didn't work. It was a ton of work and boy was she so happy she didn't have to struggle taking the riser apart because she didn't do anything other than stacking the bricks up. I was like OMG lady, you don't have a rocket stove, there is no draft at all, so all you have is nothing more than a barrel with a fire in it. But it was to late as the whole thing was totally destroyed. What a shame! She just didn't know, and I saw her build it, so much work, all wasted.

 I want to give you The Solution to a rocket mass heater, and I mean the total solution. I would like for you to copy and paste this, as well as everyone that reads this, and paste it everywhere and anywhere you can for the world to see. I will give you the big picture, the overall essence of this remarkable system, totally open-source for the whole world. Keep in mind this is all low tech and there is nothing that can be patented. There are many details but interested people can do simple research and easily find the needed info on their own so I will not go through it all here.

  Okay here we go. We have all seen those smelting factories with the huge metal bucket filled with molten metal. The bucket doesn't melt because it is lined with special refractory mix, withstanding many thousands of degrees. You can get it in 5lb bags. Look up the name of it. You then make a j-tube rocket stove, all made out of Home Depot foam boards. This stove will be all one piece, (which means it can't leak) from the vertical wood-fuel holder, and then the horizontal part at least 18 inch long, right up to the vertical RISER. The wood feed and the horizontal are square, the riser is round just as a pipe is. The horizontal reaches the riser bottom off to one side so that a vortex is created, which means that any remaining smoke will be in the fire for a longer amount of time than just going straight up. Now you have two heat sources, the wood and the gas from the smoke, giving off an intense amount of heat. The longer the horizontal section too, the more time smoke has to burn so more heat is generated. You could coat the outside of the foam-riser with something smooth, perhaps a rubber type paint, so that when finished the inside of the riser is smooth. 

  Now take this whole foam-board-j-tube-shaped- rocket-stove (all one piece, glued together or use long pins) or whatever way you decide to do it, and put it in a cheap made of wood cement-form with an inch between the foam and all the wood. Mix up the refractory and pour it in just like you would with cement. So now you have the stove-shape coated with refractory. Once cured put it in another wood form with a three inch space all around and fill the whole thing with AirCrete, which is simply Portland cement, no sand, no pebbles, combined with soap-foam, which is simply Suave shampoo, 32 parts water, I part soap, fed through a PVC like-gun and using compressed air, it comes out like shaving cream. ( For example, a five gallon pail filled half way with Portland and the other half filled up with foam, use a drill and paint mixer until a uniform color shows.) Keep doing that until you have enough.

  
 Why AirCrete? It does two things, it insulates and is a heat sink at the same time. The insulation value is way beyond anything you would ever use on a home. I mean this is theee Best insulation you will ever find, low tech and dirt cheap. The riser could put out thousands of degrees but you ought to be able to wrap your hands around the AirCrete surrounding the riser. Being a heat sink it keeps absorbing the heat and the stove will get as hot as hell.

 
  So really, how does AirCrete work? Remember as a kid when you entered the snow house you built, how you were able to remove your coat yet remain warm? This is because the snow walls were filled with trillions of tiny air bubbles, (no I didn't count them, no really I didn't) and from those walls your body heat kept backing up to your body, so in essence you were not losing body heat and you felt warm. Yet a thermometer in there would indicate the outside air temperature since a thermometer does not have body heat. Oh yeah it is cold in there.

  
  Okay, so however you build your rocket mass heater it is up to you. So, here is another really good part. The mass is made of broken-up pieces of AirCrete. Make cement forms 2 or 3 inches thick, any length you want, and when cured break it into pieces with a hammer. Completely fill the mass-box-couch, or whatever you want to call it, and while the AirCrete does give up its heat, it gives it up extremely slowly, so depending on size, (up to you) after a three hour intense blaze you could keep the house warm for 1, 2, 3 or more days. Keep in mind you are creating a crazy amount of intense heat, and not losing any of it.


 A little advice, after a few days when you remove the stove from the form, submerge the entire thing in water for thirty days, and believe me it will cure. Ever hear of spraying a new patio with water, or covering it with a canvas tarp as the tarp will hold water longer? The slower it cures the less chance of cracking. After 30 days let it sit outside to dry for two weeks at least. Then, outdoors, just this part, make a tiny fire and let it burn out. The next day make another tiny fire and let it burn out. Do this for a week. Then make a fire a little larger, do this for a week. The idea is to get rid of every tiny bit of moisture, which is the thing that could cause cracks. By the way, the refractory stuff has a high amount of strength. The AirCrete is very light in weight, can be sawed with an ordinary saw, and can be scratched with your fingernails. But in this use it will never come in contact with anything. Some guys make a regular wood stove out of AirCrete and simply cover it with sheet metal. The stove gets real hot and then slowly releases the heat into the house. Many ways to make any stove.
 

 If you do this project right it will last a lifetime. How much is that worth? Take your time, figure it all out before starting, know what you are doing. It's a simple project but not really as the devil is always in the details, of which preparation is the largest part of any kind of project. Do it right the first time and it will show you its love when you get up in the morning and when you get home from work. I've read that rocket stoves use only ten percent the wood used in a wood stove, but now with AirCrete I believe you are in for a pleasant surprise. Imagine that, no more back-breaking work splitting tons of wood.

 
 Okay Guys, hope this helps, please put it out there for all to see. 



 

[grisha]

Hello Cedro, to me it seems that yes, you have undersized your system and made some mistakes.

You can calculate how much energy you need to heat up that amount of water to desired tempeture, and then with that number of kW you can tell how many kg of wood you need to burn just for the water. But you also need to consider that a lot of heat is given to the room thanks to the barrel.

And when the barrel and coil have taken most of the heat, then it's normal that the bench won't heat up enough and gets cold soon, it also looks that you bench is rather small, it doesn't have much mass that can store heat. And I totally agree with Dan - stone wall absorbs the heat really well and makes your bench cold soon.

Another thing - isn't the copper coil diameter too small? I would think this makes heating the water more slow, and in time the diameter will be even smaller, because of the scale building up. I might be wrong here, have little experience with water systems.

Also, if your riser is uninsulated, it can't perform like a real rocket, see this thread: donkey32.proboards.com/thread/631/insulate-heat-riser-masonry-rocket

I can't see any easy solution for you, maybe I would do a test run with the barrel somehow insulated, covered with superwool of just rock wool. Then you can see how much this affects the water and bench. But really you should open it and insulate the riser.

On positive side I would say that it's a nice idea of having the bench somewhere else, and you have a decent chimney.

And sorry for my bad english, not a native speaker.