rocket mass heater riser - the five minute riser

Fox James wrote:The problem with coating ceramic fibre inside a heat riser is finding a suitable product to do the job!

However there is a product called Zircon that has recently come to my notice and is for sale from my refractory supplier.
I have not tried it although I will be ordering some ….

Fox, did you have any luck with this product as being a workable solution on or for 5 minute riser material?

Fox James wrote:The problem with coating ceramic fibre inside a heat riser is finding a suitable product to do the job!
If the stove has been built carefully to proven specification then there are very few materials that will stand the heat, especially    near the bottom of the riser!
Water glass is something that is cheap and might work for some folk but from my own experiments it cracks very badly then leaves a lot of fibers exposed.
However there is a product called Zircon that has recently come to my notice and is for sale from my refractory supplier.
I have not tried it although I will be ordering some ….

I saw this was posted a year ago?  so Fox James, have you got this down to a science?  I need to have good longevity for this. I do have access to waterglass  I suppose folks have tried Kiln Wash, or even fire brick mortar in a thin state..

Just wondering.  I have a need to get a 7"size, 36" long  (8" if you consider that my whole system is a 7")

Scott

I must of missed that post!
Funny enough I just used my old 5 minute riser in my last video and I felt ill at ease just touching it haha…

That particular one was used for at least two years and is coated with Vitcas ceramic fibre rigidiser.

It has worked and appears to be still forming a crust on the surface though be it, pretty delicate.
The zircon works ok on ceramic board and I think might be ok on ceramic mat but it has badly cracked and flaked on vermiculite board.
Vitcas are experts and suggested their  riigidiser would be the most suitable product they stock however that was several years ago and they have new products now.
Personally I am trying my best to stay way from ceramic fibre products and I am using cast thin wall risers  with an outer tube filled with loose vermiculite. (Also can seen in my recent videos)

Fox James wrote:I must of missed that post!

It has worked and appears to be still forming a crust on the surface though be it, pretty delicate.

The zircon works ok on ceramic board and I think might be ok on ceramic mat but it has badly cracked and flaked on vermiculite board.
Vitcas are experts and suggested their  riigidiser would be the most suitable product they stock however that was several years ago and they have new products now.
Personally I am trying my best to stay way from ceramic fibre products and I am using cast thin wall risers  with an outer tube filled with loose vermiculite. (Also can seen in my recent videos)

If I can inquire a bit more... having never done so, I have no idea, but...if was to use the "ceramic wool" method for the riser above the top of the batch box height-- And coated it, with anything, is this still considered DELICATE?  

Having the flames get through the port, and then started up the riser, are we still at this delicate stage?

I fully understand folks using this where they can just pull a barrel and replace or inspect things, but when the riser is deep within a large mass bell (all brick) this is simply not the case. Even an inspection is hard without a snake camera.

cheers
Scott

If you are concerned then perhaps use split brick and wrap that with ceramic fibre?
How do you intend to close the top of the bell or clean out the floor ash?
Personally I would want to have access to the core and riser.

Delicate in this context means the coating has been baked hard to the extent of being fragile, it is possible to crack it by pushing it with a finger.
You dont have to coat the fibre with anything and it should last for years but, it will by then have become a hazardous material and potentially deadly if breathed in!

So ‘delicate’ also means to me, that I have to be very careful not to break the coating that is containing the danger, but delicate does not mean the riser would not still Function.

Fox James wrote:If you are concerned then perhaps use split brick and wrap that with ceramic fibre?
How do you intend to close the top of the bell or clean out the floor ash?
Personally I would want to have access to the core and riser.

Delicate in this context means the coating has been baked hard to the extent of being fragile, it is possible to crack it by pushing it with a finger.
You dont have to coat the fibre with anything and it should last for years but, it will by then have become a hazardous material and potentially deadly if breathed in!

So ‘delicate’ also means to me, that I have to be very careful not to break the coating that is containing the danger, but delicate does not mean the riser would not still Function.

That explains this a lot better to me, as I was always thinking that folks were saying "delicate" like it was going to fall to pieces.  

As for the top of my bell, it will be somewhat close to the ceiling of my room (about a foot away) so was pretty much following exactly what Peter has said to do and how.  in this case, fire bricks from the level height of the riser to as high as I can go with fire brick.  T bars on top  (upside down of course)

I have been working with Thomas (Montana-USA)  on construction ideas, and he has been a great help. I have NOT CHANGED any of the dimensions that Peter has called out for 7" size.   I have full photos from beginning to date.  But only will post, when complete and working as expected. I do not expect to deviate and thus causing big problems.

AS for cleaning, I have my flue exit, and a clean out on opposing side, so will have access to the entire bell.  IF all goes as planned it will have a similar look to Peters size wise.  

Lastly- and this is just on the "intention side of things"  if my  metal front fits and works as hoped, I will have access to the front of the bell, but this is mostly cosmetic, and will only detail if it works as intended.

thanks to all.  And if all goes well, there will be coals in the box by fire season.  I cut trees as a side work, and have 15 years of wood under cover.  A nice side benafit.

Chris McClellan wrote:Mud: The metal exoskeleton of the 5 minute riser can be hardware cloth or steel remesh (generally used to reinforce concrete) or my favorite is to use a piece of the next larger stovepipe. (Caution, hardware cloth is galvanized so it could offgas zinc at you). Life span has been about 3 years with the hardware cloth before needing a rebuild, longer with the stovepipe surround.

Could you let me know how often the fire is lit for the three year lifespan?  I only need the RMH for 3 months of the year so  might get 9-12 years out of this 5 minute riser if you use yours every day for 3 years.
Thanks
Mike

Hi Mike;
A five minute riser using a section of stove pipe as a sleeve will last for many years.
I have two bathboxes, both in uninsulated buildings.
They burn all day every day in northern Montana, I call this severe duty batchbox burning.
Both risers are as solid as the day I installed them (several years back at the least)
I could see hardware cloth melting off over time and causing issues... so why use it?  
Metal stove pipe is built to be installed on a typical box stove and have 700F+ temps for years.
They do not wear out as a direct chimney and they will not wear out as a riser sleeve.

In your insulated home with only a 3-month winter, you will be burning once or twice a day... a properly built 5 minute riser will last longer than you in that work environment.

thomas rubino wrote:Hi Mike;
A five minute riser using a section of stove pipe as a sleeve will last for many years.
I have two bathboxes, both in uninsulated buildings.
They burn all day every day in northern Montana, I call this severe duty batchbox burning.
Both risers are as solid as the day I installed them (several years back at the least)
I could see hardware cloth melting off over time and causing issues... so why use it?  
Metal stove pipe is built to be installed on a typical box stove and have 700F+ temps for years.
They do not wear out as a direct chimney and they will not wear out as a riser sleeve.

In your insulated home with only a 3-month winter, you will be burning once or twice a day... a properly built 5 minute riser will last longer than you in that work environment.

Just to add to this, if your in farm country, anywhere there is grain moved by augers.  There is almost always a endless supply of auger tubing, from 4" to 13" in diameter. this is even heavier, and often has a flange at the base or start of the tube.  it could work perfectly for some of you. And the cost is almost always right.  (not much)

Thomas Cleman wrote:What if one were to tile the susceptible area at the bottom of the riser with these?  Graphite tiles.

You will get a very hot burn, once. Graphit burns like coal in the presence of oxygen.

...well, the reason why "graphite burns like coal" is perhaps the fact that graphite is coal