Remy Fils

Hi guys
Thomas: thank you! Will definitely follow the thread. Too bad I live in Africa, I just go to the farm in Italy on summers for the moment...

Cristobal: Yes I think you're right. Could be a BBR or even a J-Tube. I've seen how much difference can a little stove (higher in a photo in the thread) do, so I can't imagine a RMH.

Another solution to explore I've seen in a few threads (like this one https://donkey32.proboards.com/thread/3377/air-ducts-heat-distribution ) could be to use air ducts for upstairs heating. My concern is, won't it transmit noise easily from a room to another?

Hi Cristobal. Thanks for once again looking carefully at my situation and proposing amazing ideas!

I have to admit that, having never built a RMH before, I’m a bit hesitant about going “state of the art.” Starting with something more conventional, familiar, would feel safer. I’m not saying I don’t want to try it, but I’d need to find someone in Italy who could guide me a bit through the project. In any case, I plan to gain experience by helping on a participatory RMH build, but even there I’d prefer to work on familiar territory.

My first question was whether a RMH suits my house specs..? In the end, all rooms already have radiators installed. But thinking about the whole system, heating water in a basement boiler and losing heat through the flue just to warm radiators seems counterintuitive—especially with our humid winters and mold-prone walls. Installing a small temporary wood stove in the kitchen/living room quickly improved air quality (by drying it) and raised temperatures with a lot more ease than the central boiler + radiators, proving if needed the importance of radiant heat, especially in my configuration. So in the end, all roads seem to lead to RMH...

I see two alternatives:

- Multiple RMHs: smaller units could be built. 3 would be enough: two on the ground floor and one in the large bedroom upstairs. The rest of the house would rely on the central boiler for occasional guests. But I imagine managing three fires at once might be tricky...Having never used RMHs, I can’t really judge how managing multiple units compares to one or two. With classic stoves, I’m comfortable with wood reloading routines for 3 stoves; with RMHs, I just don't know.

- Take advantage of my 2000 L water tank, connected to a RMH with a water-to-water heat exchanger as proposed by Walker (“broaudio" on youtube): safer than an air-to-water system because the water isn’t pressurized, but it would probably require running the RMH for several hours per day to heat enough water for the radiators, which may be more demanding than using three isolated RMHs, in the end. Other problem, it could transform the room where it's located into an oven, because of that daily fire duration.

Lots of questions, but it’s certainly important to consider these points before committing to the build.

Thanks again!

Remy

Hi guys!

I’ve finished insulating under the roof, using 37 cm thick straw bales. This winter will show the impact on indoor temperatures. Next summer I’ll move on to the floors, while the exterior walls remain a major project for later. In the meantime, I’d like to build one RMH. At first, the goal is to reduce firewood use by 50% while keeping the existing heating system for part of the house and hot water. Later, I’ll consider a full transition.

The challenge is to heat as many rooms as possible, given that the house is built with cement blocks (and stone for some older walls), which makes interior walls highly insulating. We started discussing this earlier in this thread, but several things have changed:
- We’ll remove the partition wall between rooms 4 and 5 to create one large master bedroom (room 4).
- My house sketches were inaccurate. This matters for heating room 1 and bathroom 1, which actually share a wall—making heating them easier. Here is the accurate version (please note that the rooms are more or less at scale but the exterior shape is not: the house is almost square lol:

- I’ll now focus on heating only the essential rooms. That means the whole ground floor plus room 4. Other rooms and bathroom 2 can rely on the existing system when needed (e.g. for guests).

Based on Cristobal’s idea and this simplified approach, the best plan seems to be two RMHs:
1.  To quote Cristobal, "The first in the kitchen/living room, with a taller bell that would go through the ceiling to also heat room". Do we have any documented examples of RMHs adapted to heat two floors? Ceiling is 2,50m (8,2 ft) high. I guess with a bell type, we have no cob bench (which is ok for me: very little clay in my zone; I like classic sofas; I prefer to transfer part of the heat on first floor than heating too much the living room+ kitchen). With a tall bell like that, won't the weight be hyper concentrated in a small surface, as opposed to a long cob bench?
2. A smaller one in room 1, partly extending into bathroom 1. But this would come later—my priority is the first unit.

Again thank you for you inputs.
All the best
Remy

Hi guys,

Made my first bone sauce yesterday. The fire burned for 3 hours, then I buried everything under ground and let it sit overnight.

Unfortunately the result is much more liquid (and a lot more quantitative) than Sepp's video. Smells awful like it should be I guess though. Any bone sauce expert view on the matter? I'm asking myself if my clay was really effective in the sealing process (maybe I didn't put enough of it).

Thanks!

Thanks again guys for your help.

Cristobal, today I'll try to remake the simulation with the new website, as there are some things to be changed:
- Climate data you put is too cold, it's the climate we had here 30 years ago
- I have triple glass windows
- I'll put 40cm mineral wool insulation on ceiling + insulation on main floor + wooden floor this summer

With those new inputs, I guess we could lower by 40% at least the heat loss you obtained in the simulator.

If RMH doesn't provide a significant advantage over my actual system (like -75% wood consumption), it won't be interesting because my actual system provides better heat distribution and warm water for bathroom use. But I'm almost sure it will do, because I'm throwing a lot of heat to the chimney and I don't have the radiant heat of an RMH system.

Central heater's gas exhaust is 200°C (392°F).

Edit: with new input data: (I didn't change climatic data though because although I have higher temperature, there are strong winds here in winter that directly impact wall heat loss) I obtain:
- 15,5 kw peak and 9,7 kw average (uninsulated)
- 12,7 kw peak and 7,9 kw average (40 cm mineral wool on roof and 7 cm mineral wool on ground floor - which are short term work I'll do this year)
- 4,5 kw peak and 2,1 kw average :O  (all above + 36 cm straw insulation on walls - longer term as it is a bigger work)

So as you said, insulation first!!

Cristobal Cristo wrote:Remy,
For the area have you used the area of exterior walls?

Yes

Cristobal Cristo wrote:Remy,
Are the exterior walls over a meter thick (42")?

Conversion error...Used metric system. Let me change it

Cristobal Cristo wrote:
Are the concrete or hollow blocks or bricks?

I guess hollow blocks. No bricks for sure.

Cristobal Cristo wrote:
You put 35" for the ceiling thickness. Is it some conversion error? The same for the floor.

My mistake

Cristobal Cristo wrote:
Please provide house dimensions: length, width and height, and I will play with it myself.

Ok let me get back to you shortly. Thank you!

Edit: correcting metric system error gave me even worse numbers: 70 kW heat loss!

For insulation, maybe I should put in the calculator what my intentions are (on roof and main floor short term), instead of how is the house today (uninsulated)..?

Dimensions:
Floor surface: 737 square feet
Height: 19 ft
I know floor surface, but not exact length and width (I'm not there at the moment to take the measures). So to calculate wall surface, I took square (737)*19*3+square (737)*19*0.3. I didn't multiply *4 walls because the fourth wall is adjacent to another wall (barn's wall), so it's not fully exposed to outside temp. To take in account this, I considered 1/3 of the heat loss of a normal wall instead of 1.

Thank you again for your kind help.

Hi guys!

Here it is: https://jmp.sh/s/HvO2r8Y4CnpNZOjsnOVf

It's even worse, last calculations give a 35 kW result.

And yeah I did put "unheated" both for the room up the ceiling and under the main floor.

In any case, what Cristobal said is right. Before building the RMH, i may insulate correctly the house and see what happens in terms of wood consumption with my actual system. Oh, i forgot to mention that I have a solar panel for hot water that covers our hot water needs for whole summer and for sunny  spring days.  Question about main floor insulation: is it a good idea to put thermal insulation + wood floor on living room, knowing that I will probably destroy part of it to put my RMH there?

thomas rubino wrote:Hi Remy;
Support columns are a good idea.
Have you chosen a build design yet?  
A J-Tube with piped mass?
A J-Tube into a stratification chamber? (Bell)
A Batchbox into a bell?
Single wall bell or double wall bell?
All these choices will weigh differently and spread the weight over different areas of size.

Yes, you could continue with this thread.
However, I would start a new thread for your next questions.

Here is why: Your current thread addresses a very common question from prospective builders.
Any new questions you ask may be just as important, but they will be buried under a thread header of weight restrictions.

So, any perspective builder will bypass this thread, looking for one that covers their question on, say, the transition area (another common worry).


 

Hi Thomas!

Sorry I just saw I missed your answer. Meanwhile, I continued posting...I will rename the title, for it to include also the other thematics.

I still have to keep on doing research on RMHs, but from what I've read, batchbox is the better option for my house configuration. Single or double wall bell, I still don't know at the moment!

Cristobal Cristo wrote:Remy,

I would recommend to start the journey with estimating the heat loss of your house:

https://kalk.pro/en/heating/heat-loss-calculator/

I like this calculator, because it has a list of various masonry building materials that can be assigned any thickness.
It would help if you provided a plan for each floor.
With masonry interior walls, the placement of the heater is crucial.

Cristobal,

Just made the calculation with all the measures taken. We obtain this:


If needed, I can try to share the input data.

Please note that this summer I will insulate the ceiling and the floors, which should increase house thermic performance by 40%.

John C Daley wrote:As a Civil Engineer, I am confident 100mm steel columns will work.
Have a base plate at the bottom to spread the load around, say 300 x 300mm x 10mm thick.
Using 100mm diameter pipe will ensure the L/ R ratio will ensure the column is not too slender.
A steel or timber beam at the top will spread the protection across the floor.
I consider Cristobal's suggestion of 4 / 400 mm brick columns overkill

Thank you for your input John, much appreciated!

Cristobal, so I understand that a good proportion of houses in the rural US have thin wood framed interior walls? That would explain a lot of things! On my side, when the small wood stove is fully heating the living-room, you can get a comfy 70°F but when you pass the living room door, it can easily go down to 60°F just in the room next door so what you say makes complete sense.
And what you are telling on historical evolution of Italian rural houses is true: my house had individual wood stoves until I think, 2012, when the old owner installed the centralized wood stove system in the basement, that heated hot water both for tap hot water and for newly installed radiators that ensured house heating. But what you can see is that this system is not adapted to my humid conditions and mold tends to develop quite fast on walls if you don't respect strict window opening rituals everyday. So I really think that RMH will change the house, not only for temperature, but also for air quality and interior humidity.

As you were saying, the RMH positioning will be key. Dunno if it helps, I tried to sketch the house interior. Only the livable parts. Under living room, as I was saying, there is the ground floor with technical room + cheese laboratory. Over the second floor (over the 4 rooms), there is lost roof space that I will insulate this summer. Please note that it's not at scale! Some specifications:
- All rooms are separated by 40 cm concrete walls
- A key element of the house are the stairs. It is an open point of connexion between floor 1 and floor 2. So there is not clear separation between the 2 floors, which can allow hot air to go upstairs, provided there is air circulation.
- All rooms and livable spaces are closed by doors (that we can open but not all the time for privacy reasons)
- I did put, in the sketch, the RMH in the living room. Maybe a work is to be done on satellite thermal masses to allow heat to go on other parts of the house.


As soon as I have the possibility, I make the measurements for the heat loss calculator.

As an image is worth a thousand words, here are some photos to help understanding the house:

What you see when you enter the house. Right door gives access to living-room + kitchen; Left to room 1 and bathroom. And the stairs could give the possibility to hot air to go up.


Some views of the kitchen + living room. The RMH would replace the small wood stove, extending its heat mass towards right.



What you see when you arrive upstairs. This corridor is separated to each room by a door. So the heat would eventually arrive upstairs but then wouldn't enter in each individual room + bathroom 2.


Our actual wood boiler + 2000 liter how water tank for house heating: