Why dont we all want rocket mass heaters?

[bholler]

Yes the space requirements , plus the aesthetics of a 55 gallon barrel in the living room, are major barriers to adoption of RMH by your average American

Also recall that the first mainframe computers took up the space of an entire building. "No one will ever want THAT thing in their house"

I could envision a redesign that allows a homeowner to retrofit a fireplace with the mass - either a honeycomb of firebrick splits, or a water storage feature. If the efficiency claims can be emprically proven (same house heated by Blaze King vs RMH for successive seasons) it would provide impetus to drive those innovations

I agree the concept does hold promise. But retrofitting an existing fireplace would not work. But that doesnt mean goid looking ones could not be made.

Again i have nothing against the idea as a whole. I just have problems with people claiming 1/10th the wood useage when they clearly dont know a thing about modern wood stoves. They are talking about waking up to load the stove and waking up to a cold house. That simply is not the reality if your stoves is sized properly and run right.

 

[RobbieB]

Yeah, it would be cool to have these designs in new construction and me thinks it could be "traditionally aesthetic" pleasing too. Not to mention good for masons.

I'm thinking rocket stove with glass front and 2 mass absorber / diffusers either side in the big traditional hearth up to the ceiling. If well insulated could even be incorporated on outside wall of house.

 

[twd000]

I agree the concept does hold promise. But retrofitting an existing fireplace would not work. But that doesnt mean goid looking ones could not be made.

What makes you so certain that a fireplace retrofit RMH couldn't be designed? That how insert stoves work, and it has made them adopted more broadly in existing construction situations.

 

[bholler]

What makes you so certain that a fireplace retrofit RMH couldn't be designed? That how insert stoves work, and it has made them adopted more broadly in existing construction situations.

There is just to much going on with a rmh and not enough room in a fireplace to do it properly

 

[twd000]

There is just to much going on with a rmh and not enough room in a fireplace to do it properly

In the current design, yes. But that won't necessarily be the final design. It's essentially a heat exchanger, you can play with the mass/volume/surface area numbers in an infinite number of combinations to achieve the performance you need. My un-used fireplace has over 12 cubic feet of volume. What if a refractory shop made a honeycomb grid of firebrick cement? Like the grid size of a catalyst, without the platinum. There's your surface area. Plus the hearth, which extends 16" in front, and you could bring mass up to the ceiling.

 

[bholler]

In the current design, yes. But that won't necessarily be the final design. It's essentially a heat exchanger, you can play with the mass/volume/surface area numbers in an infinite number of combinations to achieve the performance you need. My un-used fireplace has over 12 cubic feet of volume. What if a refractory shop made a honeycomb grid of firebrick cement? Like the grid size of a catalyst, without the platinum. There's your surface area. Plus the hearth, which extends 16" in front, and you could bring mass up to the ceiling.

I have taken out lots of fireboxes to rebuild them and taken down lots as well. Very few have a large open space in them to work with. Most have allot of masonry inside that shell. In most cases it would be cheaper and easier to take it down and start over. And at that it would really only work with interior fireplaces. Which atleast in this area are few and far between.

 

[bholler]

What makes you so certain that a fireplace retrofit RMH couldn't be designed? That how insert stoves work, and it has made them adopted more broadly in existing construction situations.

With mass heaters wether it is a rocket or traditional madonry heater you need acess doors to clean all of those passages out. Integrating them into a pre exisyong structure would be a real pain as well.

 

[maple1]

I am also very doubtful that a heater you can sit on & lay on will be sending very much heat to the more outer reaches of the structure. It is still a space heater, as is a stove. And some seem to have issues getting the outer reaches of their house warm enough even with surface temps 4x or more than that of a mass heater. Radiant heat is a good thing but it will only radiate so far. Old cast iron hot water or steam rads can be very comfy too but they are a lot hotter, and you need more than one of them in a room of much size.

Should just stick to the efficiency side & claims, rather than trying to convince people they can heat 10x as good as a wood stove or heat to the same level of comfort on 10x less wood. That's where the credibility goes a bit sideways.

 

[paul wheaton]

I'll say one thing that strongly favors the mass heaters efficiency claims and I see it here often.

"Help my stove is cooking me out of my house" And here's the common response "Open the windows"

Now if you are venting all the excess heat to the outdoors you are not too efficient no matter what the stove spec is.

I don't think the rocket mass heater guys suffer this problem.

True. The temperature change is much slower.

Along those lines, if you have a couple dozen people over, without a rocket mass heater, you might find that you need to open a window. But with a rocket mass heater, I will intentionally NOT build a fire when people are coming over. The house never gets hot. I think the mass absorbs all that excess heat and then I can go an extra day of not running a fire.

In a similar vein - in the summer, it is cooler inside. I think the rocket mass heater absorbs the heat on a hot day and releases it during the cooler evening.

 

[paul wheaton]

I am also very doubtful that a heater you can sit on & lay on will be sending very much heat to the more outer reaches of the structure.

When I carefully measured last winter and heated with just 0.60 cords of wood, I spent the winter working in my office, out of sight of the rocket mass heater. So my comfort was based entirely on convective heat - nothing for radiant or conductive heat. Further, when I monitored the thermometer, it did not have line of sight with the rocket mass heater. So, again, only measuring convective heat.

Averaging about 69 degrees through the winter - measuring just convective heat.

And there is something to be said for the luxuriant feeling of sitting on the bench or sitting on the couch and putting your feet on the warm bench.

rather than trying to convince people they can heat 10x as good as a wood stove or heat to the same level of comfort on 10x less wood. That's where the credibility goes a bit sideways.

I am cool with you not believing it. At the same time, we now have techniques to heat a home with one twentieth the wood. And each year we find a few more interesting optimizations.

As I mentioned earlier, I have ideas on how I might get my wood usage down to 0.40 or maybe 0.35 cords of wood for a winter. But that doesn't even take into account some of the things that we have experimented with with bypasses and insulated guillotines. There is a possibility that I can hit that 69 degree average, through a montana winter, in a 3-bedroom home with 0.25 cords of wood for the winter. And that is still based on convective heat.


Here is an experiment I did six years ago with radiant and conductive heat, where I was able to cut 87% off of my electric heat bill.

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I suppose I could either work in these techniques, or I could add a couple more tiny rocket mass heaters into my office and my bedroom - so a few twigs would give me some conductive heat.

In this video we talk about some other experiments with conductive and radiant heat. Including a tipi we have here with a rocket mass heater:

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I encourage everybody to keep a firm grasp on your skepticism. And as time passes, I suspect that you will get the opportunity to see one in action and visit with somebody you know an trust that has one.

It isn't going to be for everybody. But I think that ten years from now, half the people that burn wood will use a rocket mass heater.

 

[edyit]

But I think that ten years from now, half the people that burn wood will use a rocket mass heater.

i get that you are really passionate and firmly believe in these heaters but i don't see 1/2 the people that burn switching to them. Heck 1/2 the people that burn don't want to switch to an epa stove let alone a 55 gallon drum and a block of concrete in their house. then there is the insurance aspect. most insurance companies want something that is UL certified and able to pass inspection. I don't know if you're going to get that with this. And lastly, for myself atleast, if i want the house at 69F for heat i'll use the oil furnace...

 

[paul wheaton]

Rocket mass heaters are now in the building codes for several cities and counties. More coming. And insurance companies are coming around.

I will be uploading a video in the next couple of days showing a rocket mass heater that has no barrel, or something that looks like a barrel. We already have hundreds of rocket mass heaters that don't have a barrel. It just seems that for hundreds of thousands of people, the barrel is not a big deal.

There is one rocket mass heater that is UL certified, and there is work being done on more.

69 degrees is the average I had here last winter. It seems I would forget to add to the fire when we got to 73 or so, and I would build a new fire when it got to 66 or so.

 

[bholler]

Rocket mass heaters are now in the building codes for several cities and counties. More coming. And insurance companies are coming around.

I will be uploading a video in the next couple of days showing a rocket mass heater that has no barrel, or something that looks like a barrel. We already have hundreds of rocket mass heaters that don't have a barrel. It just seems that for hundreds of thousands of people, the barrel is not a big deal.

There is one rocket mass heater that is UL certified, and there is work being done on more.

69 degrees is the average I had here last winter. It seems I would forget to add to the fire when we got to 73 or so, and I would build a new fire when it got to 66 or so.

Still waiting to hear what type of stove you are comparing to and how you determined the wood is safe.

 

[bholler]

And now you are claiming 1/20th for some. Come on man get serious.

 

[RobbieB]

I like to keep the house around 68 in the winter. Feels good with a flannel and a tee shirt or some sweats. The only time it gets hotter than that is when I burn the stove.

 

[edyit]

There is one rocket mass heater that is UL certified, and there is work being done on more.

when we installed the stove here, and when i have helped a few friends install their stoves this was top of their list, that the unit installed was UL certified, not even so much that it passed inspection, but that it was certified. I was told even if you had an uncertified unit that passed all clearances required they wanted nothing to do with it at all. I know insurance agencies can vary but that part stood out to me.

 

[maple1]

I encourage everybody to keep a firm grasp on your skepticism.

Encouragement not required, my skepticism isn't going anywhere.

It isn't going to be for everybody. But I think that ten years from now, half the people that burn wood will use a rocket mass heater.

But it isn't skepticism that a RMH doesn't heat efficiently - it is skepticism over your other claims you keep bringing in about other things woodburning. Ooops there's another one. ^

At the same time, we now have techniques to heat a home with one twentieth the wood.

And another. ^

 

[firefighterjake]

I am a bit skeptical that hundreds of thousands of folks are going with rocket stoves . . . I can see these appealing to certain folks, but not this folk.

 

[electrathon]

I absolutely love the discussion that has been going on here. My personal belief is that the future of stoves will be some sort of mixture of what many of us now consider to be a modern stove and the rocket stove design. I am not sure what that will be, but it will be fun as designs move forwards and evolve.

 

[maple1]

Yes - it is good discussion. May be something we can all agree on.

 

[paul wheaton]

As promised, here is the new rocket mass heater that has no barrel (or barrel-like thing):

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[paul wheaton]

when we installed the stove here, and when i have helped a few friends install their stoves this was top of their list, that the unit installed was UL certified, not even so much that it passed inspection, but that it was certified. I was told even if you had an uncertified unit that passed all clearances required they wanted nothing to do with it at all. I know insurance agencies can vary but that part stood out to me.

A lot of our laws are "thou shalt not innovate." So somebody has to be bold enough to create this stuff and demonstrate it so that laws can be changed. Fortunately, there are a few spots and situations where people can do their own thing. And a few folks that live in places where it is illegal, but they choose to blaze that trail.

As for the one that is UL listed .... it is all steel. And an issue with rocket mass heaters is that they are pushing for temperatures in the core of over 1800 degrees F. Some are even getting close to 3000 degrees F. Steel spalls at about 1600 degress F and is liquid at 2600. Steel cores for rocket mass heaters can work, but only for the smaller sizes - and then they need to be air cooled to keep them from getting hot enough for spalling.

 

[Seasoned Oak]

Im sure more people would have these heaters if you could buy it at Home Depot . Or at least a Kit.

 

[maple1]

As for the one that is UL listed .... it is all steel. And an issue with rocket mass heaters is that they are pushing for temperatures in the core of over 1800 degrees F. Some are even getting close to 3000 degrees F. Steel spalls at about 1600 degress F and is liquid at 2600. Steel cores for rocket mass heaters can work, but only for the smaller sizes - and then they need to be air cooled to keep them from getting hot enough for spalling.


Why not use some refractory in strategic places? Combined with air flow in strategic places?

A lot of us on here have gasifying boilers (present company included), also commonly subject to those temps in the secondary chambers, and also commonly utilizing refractory.

 

[paul wheaton]

Im sure more people would have these heaters if you could buy it at Home Depot . Or at least a Kit.

I agree. In the hopes that somebody does exactly that, DVD 3 of my 4-DVD set is all about "shippable cores". I hope that somebody starts just such a business.

There are some businesses out there that currently do shippable cores, but each one has something that bugs me to make it so that I feel we aren't quite "there" yet. I think people would be willing to pay about $500 to their door for a core. And I think that something with duraboard, foaming cement and firebrick could have a materials cost of less than $100 per unit.

https://permies.com/t/31100/Rocket-Mass-Heater-Shippable-Core