Need help with overall heating plan

Hi,
I am new to this forum.  I hope I am posting in the right place?   We live very rural, and totally off grid.  We have an older stone home with minimal insulation on our property.  We generate all of our electricity with a hydro electric plant.  For the last 27 years we have had an abundance of electricity from our hydro plant.  We have heated this stone home with electric heaters.  This has been quite satisfactory.  Climate change is affecting the flow in our river and thus our electricity production.  We need an alternative to the electric heaters.  There is no basement and no attic, thus no place for ducting.  I have uploaded the basic floor plan for the house.  There are 2 very old, totally inefficient woodstoves in the house.  We are planning to replace the stoves with high efficiency double burn stoves.  There is a 5” gap at the top of the Adobe Brick walls between the top of the wall and ceiling that I hope will serve to move heat into Rooms C and F (on the floor plan.  All the doors between the rooms can pretty much stay open all the time.  I am hoping this will be sufficient to “spread” the heat throughout the house.  Any suggestions and/or comments about this plan?
The exception and what I mostly need help with is Room A.  There is an older man with health issues that lives in this room.  For a number of reasons, the door between Rooms A and D must stay closed most of the time.  It is important that Room A stay consistently warm.  The wall between the rooms is a standard framed sheetrock wall.  I was thinking of cutting some small vent openings between the rooms and using small circulation fans to move warm air into Room A.  I have read that using fans can create negative pressure issues in Room D (in our case) that could cause back drafting in the woodstove.
Any help with how to proceed would be greatly appreciated.  Will fans be an issue?  Where to place them?  What else might work?  Is there any other approach that is better?  Does it seem like the overall plan for the house will work?
Thank You.

I would highly recommend looking at a Rocket Mass Heater.

Here are some youtube videos to introduce the RMH if you are not familiar with them.




https://permies.com/t/137208/Uncle-Mud-Liberator-Rocket-Mass




https://permies.com/t/100425/clearance-RMH




https://permies.com/t/156037/Zen-art-Rocket-Mass-Heater




https://permies.com/t/204370/RMH-questions-start-building


I am looking forward to what other folks might suggest.

Thanks.  I am now studying and learning about Rocket Mass Heaters.

Hi, I have done a little studying and have some questions.  It seems from what I learned so far that each rocket mass heater is somewhat custom to the installation.  Seems like there are design options that can be employed to achieve different characteristics of any particular installation.  I would like to summarize what I want to be able to do and see if you can tell me if the rocket mass heater is a viable option.

First off, the space we have available for whatever we do has a footprint of 5’ x 3.5’.  Everything I have seen so far for rocket mass heaters has the thermal mass beside the rocket stove, basically on the same level.  Is it possible to build your mass vertically from the floor and have the rocket stove mounted on top.  We have plenty of clay available for making a cob mass.  I envision a mass that fills the 5 x 3.5 space available and is built up as high as possible to create the largest mass possible and still have the rocket stove on top of it.  I posted an attachment with the floor plan for our building when I first initiated this thread.  The 5 x 3.5 space is in Room D where “existing” woodstove is.  The floor is a concrete slab and the two walls next to the existing stove are adobe brick, so there are no combustibles near this space.  Could the mass be built in contact with the adobe walls so they become part of the thermal mass?  The ceiling is 8’ high and is made of wood, so clearance would be required there.  The total square footage of the building is just under 2000 sq-ft.

I found this on the internet about rocket stoves:

       It takes time to maintain the fire during the first hour. It has to be tended more often than a
       regular fire in a wood stove. Even after it's running well and we forget to add more wood
       within an hour, it will burn out.

Is this true?  I would like a system where you build a good fire and then you only need to tend it once or twice a day.  Is this possible with a rocket mass heater?

We have a hydraulic wood splitter that mounts on the back of our farm tractor.  It works well and is fast.  Do you see any problems using it as long as we split the wood small enough to fit into the fire box?  I ask because the wood will most likely be larger than branches or twigs, but I’m sure I can get it small enough to fit the fire box.

A rocket mass heater does need tending to when firing it on the other hand it gives of heat for many hours or days depending on design used. So yes it takes some tending till the mass is hot then you are done with it. The mass is the key to it taking far less time over all to deal with then a standard wood burner. The mass is also what helps it efficiency by holding heat that would go up the pipe and outside. Research some more about rocket mass heaters and you will see what I mean...
   

Orientation?(what is north) and what about windows in the walls?

Somehow I missed this post, hopefully you'll read mine.
It seems that you are shifting to a pure mass heater, no barrel. Since this can be built as an upright monolith it'd fit inside the 5' x 3.5' footprint. The location in room E would be ideal, the adobe inner wall will get warm as well. Room F and its batchroom will be very comfortable.  Room C won't be heated this way, only marginally. With all the doors open all the time, the rest of the house will get warm(er) eventually but not as much as room E and F. Most of the heat from a pure mass is radiation, coming more or less at right angles from every surface. So, not much warm air to distribute through the house.

Pure mass heaters are fed once or twice a day, burn their fuel within an hour or maybe two and go out. Those heaters have a door and all the fuel is fed in one go, or that's the general idea. The fuel can be larger also, it doesn't have to be branches or the like. The masonry of the heater will take up the enormous amount of heat that is generated by that roaring fire and gives it slowly to the room during the following 12 to 24 hours. Most pure mass heaters aren't small, weighing several tonnes. Suffice to say, the room where those are will be warm all day and night. Due to the fierce burning, most mass heaters burn surprisingly clean, forget about sweeping the chimney twice each season.
Power of these heaters into the room isn't high, the trick is the constant dissipation of gentle radiation.

Mark Twain said something about these heaters.

Keeping room A on a steady temperature won't be easy, since it's a small room. On a technical level, the heating demand is ideal for a pure mass heater. Maybe a small one, like a 4" or 5" mass heater in the room itself might do the trick.

One design that's particular good in burning efficiently is the batch box rocket heater, see https://batchrocket.eu/en/
Lots of experience has been built up with these heater cores, so it's quite well known how to operate these, what comes out and, most importantly, why it is working like it does. Regarding tending, this is close to ideal: fill the firebox, light on top of the pile, close its door and walk away. Come back in an hour or an hour and a half and close the air inlet. For room E a sidewinder might fit the bill.