Fire proof cement vs. fireproof bricks

Greeting!

Fireproof bricks are about 6 dollars a piece where I live, while a bag of 5 kg fireproof cement is 23 dollars. Can I mold my own bricks - any other ideas?

Best regards
Øystein

Hi Oystein;  Welcome to permies!

I see you are in Norway.  Products available and costs will be different.

On to your question,  Yes, you could mold bricks or cast a core , but only if the temperature rating on your fireproof cement is high enough.

Do you know the ratings on this product ?  What is the brand name ?  We have many members in northern Europe & Scandinavia they may have experience with that product.

Do you have Ceramic fiber boards available ?  Ceramic blanket ? These are the newest products being used in building RMH , with them you only need regular clay bricks to build , not fire bricks. Cost can be high with these ceramic products but the benefits of using them seem to negate the cost.  

It is not so easy to mould your own bricks with plain refactory cement, in fact it is really differcult unless you can find a suitable binder.
I am guessing that the cement is Fondue but on its own it is of little use to you, what you need is castable refactory product that contains crushed fire brick and very often other binders like stainless steel needles and plastic burnout fibres.
However.. even with castable refactory you really need some form of vibrating table to produce anything decent.
As Thomas says, there are now high temperature refactory board available, the board can be cut and shaped to size and is great for any aspect that won’t receive a lot of abrasion.
What are you planing to build?

Greetings,

and thanks for keeping this forum great! Could Leca, the puffed clay balls, be a suitable binder for refactory cement?

I will post some pictures to give an idea of what I am building.

Øystein

I plan to pass water through a copper pipe system to cool it down and fill a tub with the water. I want it to cool down the area above the wood feeder first. Then the area where the exhaust enter the bench. And finally the barrel.

To the top left of the bread oven I plan a vegetable grill. The duct will be to the top right. I hope to order a door With a fireproof window installed, as I can't see myself making one..

I want to build a stone wall surrounding the barrel. I also plan to build a tall chimeny on the outside of the house.

Here is a link to a prototype I made. For the curious souls..

https://www.youtube.com/watch?v=tYxoEan2QWY

To make short summary of this build.

1. I want to try to find the optimum working temperature for the stove, and try to keep it at this temperature using air and water cooling systems.

- Air cooling: the metal stove will be able to radiate heat to an area below the wood intake(1). This area reaches from under the bread oven and under the shower the floor, to a duct I plan to build leading to a main ventilation channel for the entire house/cabin. It will also be able to release het to the left and right of the burn channel (2). I want to be able to use this heat to grill vegetables. If you see the build from the front, I will make a door to be able to close the opening on the left hand side. The stove will also be able to release heat to the stone it is resting on (4). That stone functions as is the roof of the bread oven, I hope it will heat enough to bake bread. The stove will also be able to release het from the area between the barrel, and the wood intake (5). This duct is very useful as it allows great access to the area just below the chimney. I plan to burn a torch/big candle there to pre heat the system before starting a fire at the wood intake.
- Water cooling. I want to install a copper pipe system - not sure about dimensions yet. It will cool three different areas. 1. The area above the wood intake. I want to make a coil to keep this area as cold as possible, to reduce the possibility of smoke. I think a coil with 5 turns should be enough; I don't want it to tall. 2. I will then lead the water to the area where the exhaust is pushed down into the bench. I plan to get a copper coil that is 50 or 25 meters, the majority of which I will use in this part. Then I will make a last coil around the barrel (3). This to ensure I can get a nice temperature on the water before it goes to the sunken bath tub.

The plan is to completely cover the barrel with a stone wall, and place a big tile on top. I want to be able to use the heat that is accumulated in this space, and pass it through a closet to dry clothes, fruit, etc. before it leads to main ventilation duct.

I think these are the main cooling/insulating aspects of the build, and in sum will give me some tools to regulate the temperature in each burning session. I also hope to make a door in the front to be able to observe the flow of hot air passing.
After passing the exhaust under the bench it will leave the house where I plan to build a tall pipe of natural stones.  








   

Hi Oystein, I would of made a comment on your work, it looks interesting but, I can’t work out what is going on from those close up pictures.

It's hard to make detailed comments without more detailed information or drawings, but the plan of running copper water coils near the hot core is troubling. Some of these areas can get so hot that any halt to circulation (like a power outage) could result in swift boiling and explosion of the piping.I understand the desire to cool the wood feed, but guiding secondary combustion air through a jacket there would be much safer, and useful in delivering hot secondary air to aid combustion.

The water heating method that has been developed for safe use is to have an open vented tank exposed to heat, with copper coils submerged in the tank. As pressurized water has a higher boiling point than atmospheric water, even if the tank boils, the coils will not boil. This can give plenty of hot water with safety.

Glenn Herbert wrote:It's hard to make detailed comments without more detailed information or drawings, but the plan of running copper water coils near the hot core is troubling. Some of these areas can get so hot that any halt to circulation (like a power outage) could result in swift boiling and explosion of the piping.

Thank you for your input. I will not use a pump to circulate the water, but natural pressure due to height difference. I will also drain all the water from the piping in between uses, and only start to circulate water when things are getting hot.

It would be useful to monitor the heat in different parts of the oven.. Every burn will require full attention.  

I will try to post some drawings as the pictures are just showing the unfinished shell.  

My biggest doubt at the moment is wether or not to keep building the oven with the cast iron core.

Hmm... cast iron core? What part is cast iron? Is the wood feed at the right in your first drawing, with the water coil around it?

Cast iron was used for commercial buildings in the 19th century, until it was found that it melted easily in fires and collapsed. I hope you are not trying to use it near the actual fire.

Glenn Herbert wrote:Hmm... cast iron core? What part is cast iron?

I'm refering to the wood stove. See picture nr. 3.

It has many advantages over the bricks.

Certainly the wood stove is sturdy, massive, and transfers heat easily. It would be fine as a shell to line with insulating refractory as long as the internal space has appropriate dimensions. If any of it is exposed to the fire, that would be bad for it and for the fire.

Hi Glenn, I have resumed the work on the stove. I was about to get the ceramic blanket insulation but then I read it might cause cancer. Best regards

http://www.hse.gov.uk/foi/internalops/ocs/200-299/267_3v2.htm

thomas rubino wrote:Hi Oystein;  Welcome to permies!

Do you have Ceramic fiber boards available ?  Ceramic blanket ? These are the newest products being used in building RMH , with them you only need regular clay bricks to build , not fire bricks. Cost can be high with these ceramic products but the benefits of using them seem to negate the cost.  

What about soot in these fiber products?

thomas rubino wrote:Hi Oystein;  Welcome to permies!

I see you are in Norway.  Products available and costs will be different.

On to your question,  Yes, you could mold bricks or cast a core , but only if the temperature rating on your fireproof cement is high enough.

Do you know the ratings on this product ?  What is the brand name ?  We have many members in northern Europe & Scandinavia they may have experience with that product.
 

I will try to make the inner pipe using this clay. The information is in polish, but from what I can read it should withstand 1320 degrees celsius..
https://bakerovner.no/produkt/ildfast-limleire/?v=c2f3f489a005

I am also reading up on Sodium silicate - maybe that could be used to cast a chimeney in perlite?

"Water glass is a useful binder of solids, such as vermiculite and perlite. When blended with the aforementioned lightweight aggregates, water glass can be used to make hard, high-temperature insulation boards used for refractories, passive fire protection and high temperature insulations, such as moulded pipe insulation applications. When mixed with finely divided mineral powders, such as vermiculite dust (which is common scrap from the exfoliation process), one can produce high temperature adhesives. The intumescence disappears in the presence of finely divided mineral dust, whereby the waterglass becomes a mere matrix. Waterglass is inexpensive and abundantly available, which makes its use popular in many refractory applications."https://en.wikipedia.org/wiki/Sodium_silicate#Sealing_of_leaking_water-containing_structures