more info on the fate of the lightweight "cyclone" heater?

[joshuadm]

Hello Donkey Board folks,

My name is Joshua and I've been learning about Rocket Mass Heaters for a few years now.  I have my copy of Ernie and Erica's book.  I am getting close to having land and a house to be able to build something permanent.  

However...at this moment I am still a renter, and the temptation to find the magic lightweight rocket mass heater solution is strong.  

The Cyclone at Wheaton Labs was taken apart, it seems, because of a lack of quick heat primarily.  I would be OK with not having quick heat, and having only the sustained heat.  But I am still not clear if this design could work in this situation.

If it can, I would declare it the Renter's Masonry Heater, and it might be something that people in cities could get landlords on board with!  

Thanks so much.


Joshua

permies.com/t/71576/tiny-house-rocket-mass-heater


Here's the last post from that thread with my questions: 




So I'm hearing that this is the thing many people have been waiting for--the Renter's Rocket.

A). It is small, takes up only a few square feet of floor space
B) It weighs less than 2,000 lbs.
C) the materials are pretty cheap (Paul said about $200 in the Uncle Mud podcast, podcasts #382-4)
D) It can qualify as a masonry heater, so you would not be required to have the chimney exit temperature.
E) a fair portion of renters rent rooms in a house, or a floor of a house, that has an existing chimney and fireplace that was filled in with drywall a while ago, but this could be opened up again.
F) Many renters will come home in the evening and have dinner indoors, vs. just coming back to the cabin shortly before bedtime. You'd have time to get your heat up to temperature. You could use an electric heat pad for the meantime while eating dinner and such. You could work around the no-quick-heat problem. You could cook on a lightweight rocket _stove_ that would heat up your space, if codes allow that, or use a code-approved wood stove instead.

Is this accurate?
Most importantly, item B, is 2,000 lbs a normal load for the 2nd floor of an old house? 3rd floor? It's the equivalent of two heavy upright pianos fit into a smaller footprint than one piano.

Also, any updates on how this cyclone rocket performed with the test of time a year _after the surgery_ or with a rebuild elsewhere? did it still have any other issues with items 1-4 after those things were addressed?

Regarding #4, the smoke-back was how it functioned before the surgery?




paul wheaton wrote:
Lessons:

1: for a batch box rocket mass heater, make sure that the riser slot is taller than the wood feed. Or else smoke will come out the front. And smoke out the front is utterly unacceptable.

2: As matt walker mentions: no matter what glass you use, the casserole lids break. I suspect that the glass that is for electric stove tops might work, but they don't come in the casserole lid shape. So it may be possible that something could be cobbled together. So we went with a cast iron skillet as a door.

3: We know that firebrick doesn't have enough insulation to be a riser, which is why one riser design is to wrap durablanket around standard firebrick. We are beginning to learn that the orange firebrick (insulated firebrick) is better, but not much better.

4: For most of the burn of this, there would be smoke. That is absolutely unacceptable.



So we solved #2. And for #1, #3 and #4 we had plans on things we could do to fix it .... but ....


5: A normal rocket mass heater in this space would probably make the space quite comfortable in about ten minutes. And really warm on a really cold day in about 20 minutes. But this rocket mass heater had no barrel for "quick heat". So it would often times take three hours to to get the space comfortable. And since it is a batch box, it was a lot of wood. And then after a long three hours, people would go to bed only to wake up an hour later to find themselves in a sauna. They would open the window so it could cool a bit so they could get back to sleep. And then wake up to a cold cabin. This is absolutely unacceptable.


All of our ideas to solve #5 were weak and probably would not help enough


Since this rocket mass heater is so beautiful, we had very long discussions about ways to save it. But in the end, we made the difficult decision: it is time to replace it. On august 26th, 2020 it was removed.


A pebble style, j-tube, 4-inch rocket mass heater is going in:

[joshuadm]

Anyone have updates on this? Thanks!

[whazzatt]

Hi Joshua

I can't address your questions and concerns about the light-weight cyclone heater directly.

But I can say that a renter's rocket heater is always going to be tricky due to the need to put a chimney through a ceiling and roof (preferably) or through a wall (less preferable). I can see why landlords and renters alike would not be keen to cover that cost - the landlord because it may seem like an unnecessary expense, and the renter because s/he will likely walk away from the home and heater at some stage. And then there might be insurance issues.    

But if one finds himself or herself in a rented space where there is a chimney, or where the land-lord will cover the expense of the chimney, or where one doesn't mind paying for the project or part of it, or where one comes to an agreement with the landlord where expenses are deducted from rent bills but ultimately the unit stays behind when one leaves, then one could consider doing something relatively affordable and effective. Something like this:





It's a 4 inch / 10 cm system. It warms up a 12 square metre cabin within a few minutes, and as I've said elsewhere, it should be able to heat a much bigger space, though obviously that would take a bit longer. It serves the secondary function of a cooking surface. You can see pics of the build here: www.perspectiveproject.co.za/2019/07/01/new-thermal-mass-rocket-heater-for-tiny-cabin/

Three seasons of heavy use, and still going strong. 

To call it a mass heater would be misleading. Only a few bricks on the top left get very hot. If run for several hours, the 'ghetto-cast' core (perlite, clay, sand, some fire-cement, and I had some old glass-rope to add for structural strength, though I think Matt used fibreglass for his ghetto cores) does transfer heat into the mass around the core. You could design and build it better so that the heat leaves the drum-radiator to enter a bell-like cavity in which the chimney would enter and sit quite low to the ground.    

Seeing as the unit heats my space so quickly, I can start a small fire in the morning and be very warm very quickly.  

I built my first wood-fired heater in a rented cabin. Actually, a cabin I financed and built on rented land. Had to walk away from it all a few years ago. Was worth it though. School fees.  

Could the entire thing be dismantled and re-built somewhere else? Yes, but one would have to break the bricks apart (easy to do seeing as I used clay-sand mortar) and seal the hole in the wall.  

I hope that provides food for thought.

Dave

[peterberg]

Jul 20, 2021 8:29:26 GMT -8 joshuadm said:

5: A normal rocket mass heater in this space would probably make the space quite comfortable in about ten minutes. And really warm on a really cold day in about 20 minutes. But this rocket mass heater had no barrel for "quick heat". So it would often times take three hours to to get the space comfortable. And since it is a batch box, it was a lot of wood. And then after a long three hours, people would go to bed only to wake up an hour later to find themselves in a sauna. They would open the window so it could cool a bit so they could get back to sleep. And then wake up to a cold cabin. This is absolutely unacceptable.

At some point, Paul seemed to think there's no room for two similar systems. So J-tube rocket mass heaters are promoted and batch box rockets are discredited as the net result.

The above shows why a pure mass heater do need a different approach. There's no such thing as "quick heat" other than through its door. A pure mass heater requires some forward thinking: in fact the burn at this evening is providing heat for the following night and day. The story is about the Red Cabin, a guest hut that's largely uninsulated. The only thing that needed to be done is burning one single batch the evening before the guests arrive.
So the above criticisms are largely due to not being familiar with the ins and outs a of a true mass heater.

Moreover, since a batchrocket is a combustion core being the front end, the back end or heat extraction part could be anything. Including a barrel, cob bench and whatnot. Even like my former workshop heater being a three barrel tower, providing heat very quickly. The whole notion of a masonry bell system is borrowed from the large Russian and Finnish heaters. All this shows the design of a heater should be tailored to the space to be heated as well as the usage and the users of this space.

Point 4 of Paul's article says ""For most of the burn of this, there would be smoke. That is absolutely unacceptable." I fully agree with that last statement, but why would there be smoke? While other batchrockets won't smoke at all, inculding the 8" one in Paul's workshop/auditorium! One reason could be this: the original riser of the cyclone rocket tended to crumble, at some point it was replaced. This was done using insulating firebricks. Since there wasn't space enough, a rectangular riser was installed.

No wonder why it didn't work as well, during years of development is became clear such a riser shape is murderous for the proper afterburner function of a batchrocket.

[fiedia]

peterberg,

I am concerned with Paul's lesson 1:

1: for a batch box rocket mass heater, make sure that the riser slot is taller than the wood feed. Or else smoke will come out the front. And smoke out the front is utterly unacceptable.

Have you tried to put the port up to the firebox ceiling to avoid smoke when one opens the front door?

[ericaus]

Aug 15, 2021 21:48:38 GMT -8 fiedia said:

peterberg ,

I am concerned with Paul's lesson 1:

1: for a batch box rocket mass heater, make sure that the riser slot is taller than the wood feed. Or else smoke will come out the front. And smoke out the front is utterly unacceptable.

Have you tried to put the port up to the firebox ceiling to avoid smoke when one opens the front door?

I've done this configuration and I've never had any problem with smoke coming out the front door, even on a cold start with the by-pass butterfly valve closed. 

[peterberg]

Aug 15, 2021 21:48:38 GMT -8 fiedia said:

peterberg ,I am concerned with Paul's lesson 1: for a batch box rocket mass heater, make sure that the riser slot is taller than the wood feed. Or else smoke will come out the front. And smoke out the front is utterly unacceptable. Have you tried to put the port up to the firebox ceiling to avoid smoke when one opens the front door?

Yes, I tested a version with the port up to the firebox ceiling. The net result was a lot more CO, and I mean a lot, indicating the mixing of the combustibles with fresh air wasn't as good. Mind you, no smoke out of the chimney since CO isn't visible to the human eye. The space above the port is important in this, see an explanation of the gas streams in the port, batchrocket.eu/en/workings#stream
Paul isn't the technical mind in this area, his recommendations could be totally wrong or not.

Of course there are ways around this particular "smoke out of the door" phenomenon. One way is to do literally what Paul recommends, leave the port as it should be and lower the door opening. I might add that all of the professional builders I know of, don't do it this way.

Another, more common way known as the upside down or Swiss method, is to load the whole batch in the firebox before it is lit. Biggest pieces first, smaller closer to the top and kindling on top. Lite on top and leave the door open a crack and the air inlet fully open. When the fire is well underway, close the door and let it go by itself without interfering for the next 45 minutes or so. By the time there's the need to refill (if at all) the chimney is hot, the whole of the heater is warmed up well and no smoke will come out of the door when opened. My own red bell heater has been operated this way for the past six years. Highest temperatures in the chimney, measured close to the heater and in the center of the stove pipe won't go higher than 120 ºC (248 ºF), around 5 to 10 times a season.

Making a small fire first and loading incrementally bears the risk of smoke spilling, that's true. Change of habit would solve that.

[peterberg]

Aug 15, 2021 22:38:47 GMT -8 ericaus said:

Aug 15, 2021 21:48:38 GMT -8 fiedia said:

I am concerned with Paul's lesson 1:

1: for a batch box rocket mass heater, make sure that the riser slot is taller than the wood feed. Or else smoke will come out the front. And smoke out the front is utterly unacceptable.

Have you tried to put the port up to the firebox ceiling to avoid smoke when one opens the front door?

I've done this configuration and I've never had any problem with smoke coming out the front door, even on a cold start with the by-pass butterfly valve closed.

Eric, your heater is a real fat one, tolerances are usually larger with such large heaters. I'd think no visible smoke is produced which of course doesn't mean combustion efficiency is on a par with the tried and tested configurations.
The only proof of the pudding is a series of real tests on your heater, using proper test equipment, of course.

[ericaus]

Aug 16, 2021 7:33:17 GMT -8 peterberg said:

Aug 15, 2021 22:38:47 GMT -8 ericaus said:

Eric, your heater is a real fat one, tolerances are usually larger with such large heaters. I'd think no visible smoke is produced which of course doesn't mean combustion efficiency is on a par with the tried and tested configurations.
The only proof of the pudding is a series of real tests on your heater, using proper test equipment, of course.

Thanks Peter, yes I'd like to do some tests sometime. If I get hold of a Testo in the future I'll be sure to share the results.