Battery size

Hello everybody.

I am planning to build 6" RMH system with batchbox which will hopefully provide enough heat for our house. (110m2) I want to combine stone/hempcrete bench and copper spiral around heat riser inside stainless steel bell connected to central heating system with water tank (500l). Now my question:

Is there limit for battery size?

I can imagine that burn time gonna be longer than system with only bench, but it should work...or am I wrong..?!

Thank you very much for any constructive comments.

Jakub, Czech Republic

Hi Jakub,
I will let the experts respond in relation to the size of the battery/mass. I do want to mention however, that I don't think hempcrete would be a good material to use for the mass. All the research I have read, suggests that hempcrete is fairly good at insulation. My understanding is that most of the mass should be something that stores and transfers heat well.

Hello Matty, thank you for you reply, but the way I understand Hempcrete is more dense you make it, more heat you store. Planning to make only skin out of Hempcrete, so hopefully it will work. Thank you, hope you having nice xmass.

I would put the coil in the bench.
Once your tank has too much heat and it raises the water temp above boiling point 100C or 212F, it will vapourize and pressurize and then explode shredding a house and its occupants. My perference would be to get one these EPA approved indoor wood/pellet boilers. https://woodboilers.com/wood-furnace-heating-indoor-wood-boiler/

With stratification there isn't a limit to the size of your thermal battery. The biggest thing is not to take out more than you put in per day/week.