I know I’m really late to the game here, and I know rocket mass heaters have been discussed before, but after just getting off the rocket mass heater train not so long ago I thought I’d give my opinion on them.
I was fascinated with rocket mass heaters for a while and thought wow why isn’t everybody doing this. It wasn’t till much later that I started to realize there are definitely a few things that make these claims seem more impressive then they are. The wood consumption reports seem to always refer to old smoke dragon stoves, which any modern stove could easily halt your wood consumption or more depending on your situation when making the change.
Secondly it wasn’t for quite some time that I realized nobody was ever mentioning how big their houses were, they always seemed to leave out the part that they were living in a small house with a loft, rarely ever exceeding 1000 square feet combined living area, most I found were closer to the 600 square foot combined living area.
The other thing that got me thinking when people reported their wood usage was this, you damn near have to split your wood to kindling size to feed these things. I know there has been some debate on this subject, but feel free to chime in if you think this may ring true. If you took a cord of wood, either while logs or roughly split for an ordinary wood stove, and then subsequently split it all into kindling size pieces and stacked it again, what would you have? Obviously I have stacked a cord of kindling, but to my thinking you would probably be looking at closer to 1/2 to 2/3 cord? Kindling pieces can be stacked extremely tight, minimizing air gap to an absolute minimum. I actually posed this question to some rocket people before asking them if their “cord per year” that they use was one cord rounds which was then susbsequently split to kindling size, or if they split their wood to kindling size and then stacked it all to form one cord, I never got an answer, just a lot of dancing around the question like it didn’t matter.
But let’s say what they say is true. I had one gentleman tell me he lived in upstate New York in a 600sqft house and he burned 1 cord per year. So let’s do some math, my house is 2400sqft, so logically I would have to burn 4 times as much as he does to keep my home at the same temperature. So already I am up to 4 cords per year. I also live in central/northern Canada with much longer and harsher winters, so let’s add another 1/2 to full cord to adjust for that fact. So I’m the end I would burn 4-1/2 to 5 cords per year to heat my house with a rocket mass heater. 4-1/2 to 5 cords per year is pretty typical for anybody in my area with a similar sized home running a blaze king, so I struggle to see where all these “efficiency gains” they speak so highly of are going?
My final thought is this however, I think it may just in fact be possible that if one was living in a tiny home that you may very well be able to see some reduction in wood consumption with a rocket mass heater vs a conventional wood stove, perhaps even a modern epa stove. My reasoning is this, tiny homes do not take many btus per hour to heat, especially if they are well insulated and especially if you are living in a medium to mild climate. I think someone living in a 600sqft home would struggle to get any wood stove to burn low enough where you weren’t opening windows and sweating like a pig while using it. So the struggle may be that in a tiny home you end up using more wood then needed because you have to more or less heat the home till it’s too hot and crack windows just to keep the temperature comfortable, even with a modern epa stove. So perhaps if you are in a decently insulated tiny home you just may see a reduction in wood consumption? Just my thoughts, feel free to chime in if you think I’m completely out to lunch.
I was fascinated with rocket mass heaters for a while and thought wow why isn’t everybody doing this. It wasn’t till much later that I started to realize there are definitely a few things that make these claims seem more impressive then they are. The wood consumption reports seem to always refer to old smoke dragon stoves, which any modern stove could easily halt your wood consumption or more depending on your situation when making the change.
Secondly it wasn’t for quite some time that I realized nobody was ever mentioning how big their houses were, they always seemed to leave out the part that they were living in a small house with a loft, rarely ever exceeding 1000 square feet combined living area, most I found were closer to the 600 square foot combined living area.
The other thing that got me thinking when people reported their wood usage was this, you damn near have to split your wood to kindling size to feed these things. I know there has been some debate on this subject, but feel free to chime in if you think this may ring true. If you took a cord of wood, either while logs or roughly split for an ordinary wood stove, and then subsequently split it all into kindling size pieces and stacked it again, what would you have? Obviously I have stacked a cord of kindling, but to my thinking you would probably be looking at closer to 1/2 to 2/3 cord? Kindling pieces can be stacked extremely tight, minimizing air gap to an absolute minimum. I actually posed this question to some rocket people before asking them if their “cord per year” that they use was one cord rounds which was then susbsequently split to kindling size, or if they split their wood to kindling size and then stacked it all to form one cord, I never got an answer, just a lot of dancing around the question like it didn’t matter.
But let’s say what they say is true. I had one gentleman tell me he lived in upstate New York in a 600sqft house and he burned 1 cord per year. So let’s do some math, my house is 2400sqft, so logically I would have to burn 4 times as much as he does to keep my home at the same temperature. So already I am up to 4 cords per year. I also live in central/northern Canada with much longer and harsher winters, so let’s add another 1/2 to full cord to adjust for that fact. So I’m the end I would burn 4-1/2 to 5 cords per year to heat my house with a rocket mass heater. 4-1/2 to 5 cords per year is pretty typical for anybody in my area with a similar sized home running a blaze king, so I struggle to see where all these “efficiency gains” they speak so highly of are going?
My final thought is this however, I think it may just in fact be possible that if one was living in a tiny home that you may very well be able to see some reduction in wood consumption with a rocket mass heater vs a conventional wood stove, perhaps even a modern epa stove. My reasoning is this, tiny homes do not take many btus per hour to heat, especially if they are well insulated and especially if you are living in a medium to mild climate. I think someone living in a 600sqft home would struggle to get any wood stove to burn low enough where you weren’t opening windows and sweating like a pig while using it. So the struggle may be that in a tiny home you end up using more wood then needed because you have to more or less heat the home till it’s too hot and crack windows just to keep the temperature comfortable, even with a modern epa stove. So perhaps if you are in a decently insulated tiny home you just may see a reduction in wood consumption? Just my thoughts, feel free to chime in if you think I’m completely out to lunch.
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