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RMH but no/little cob available  RSS feed

 
                                        
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Hi All.  

We live in an old poorly maintained and insulated house from 1890/1900 and as it's going to take a while to remodel, we need a "quick" heating fix. The ideas for a RMH are very appealing to us and we've decided to give it a whirl. Not in the last part because we still have a good supply of wood.

However ... the outer wall still needs to have stucco applied outside  (the rain has prevented that) and insulation inside, and the house is simply built on sand with a layer of concrete over it. Any heat generated will therefor probably be absorbed by the wall and floor before it is radiated into the room.

Furthermore producing cob is, for us at the moment at least, not realistic and too time consuming. However, the house came with piles and piles of bricks, both simply red bricks, white sand bricks and about 200 refractory bricks.

My question(s):

* what would be the best, and more importantly, cheapest way to insulate both the wall behind the RMH and the floor?
* can the RMH be fitted with a mass heat retaining element constructed almost purely out of brick instead of cob (like a masonry heater)? If so, which brick would be the best to use? Either/or?
* if space is not available length (width) wise to construct a bench, can we go up instead? If so, can the same diameter pipe (8" or in our case, 20 cm) be used?

I know insulation is very important, but we're still searching for a way in which to retain the "breathing" ability of the house, which has been built without a cavity wall, using two types of brick (red brick "length wise"on the outside and white brick on the inside).

We'll have to do everything ourselves, and with money being tight (read: non-existent) and 3 teenagers of which 2 are autistic, time is a valuable item as well. So once we start a project, it needs to be finished either quickly or must be able to be spread indefinitely (I think the latter will almost certainly become applicable to the remodelling of the house, but I'm not complaining ;o)

In the end, once we get to a certain point, we also want to install some form of wood fired cooking stove in the kitchen. I must admit I have almost drooled looking at Donkey's RMH, especially because we have a 150 year wood fired cast iron cooking stove without working innards which I would like to integrate in the new stove. It has a top plate with three cooking rings, working doors. etc.

So, it's a long story, but any and all input will be hugely appreciated. We've done a fair bit of research already, but hearing things from "the horse's mouth" of course is very valuable as well.   
 
                                
Posts: 98
Location: Eastern Colorado, USA
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Okay...

Question 1: Insulating one wall only, as I think you are saying, is pointless.  Since you don't have any insulation, you're looking at relying on thermal mass, which means you don't let the house go cold.  "Keep the home fires burning" as they said. 

Question 2: Yes.  Brick is fine, and if anything, you can do more with it.  Some construction methods would allow you to make a maze through the brick to lengthen the flue, which could be done without the metal pipe. You'll want fire brick for the firebox and the hottest parts of the stove.  The goal, of course, is to extract as much heat as possible inside the house, so that the smoke coming out the flue is almost cold.

Cob is for dirty hippies who spend all their money on pot and can't afford bricks.    <--- note emoticon means I'm kidding!

Question 3: Yes.  Same principle applies -- make the heat take the longest path.  Here are a couple links that show diagrams of how it works, in the case of the Tulikivi mass heater.

http://www.tulikivi.com/en/fireplaces/The_advantages_of_soapstone_Technology
http://www.soapstoneheating.com/fireplaces.php
 
                                        
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First of all, thanks for the response!   

1) I realized later on that insulating just the one wall for now, is indeed, pointless. I recently found out that an uninsulated (thick) non-cavity wall has certain advantages, as the dewpoint is closer to the outside environment. This will facilitate evaporation from the inside to the outside, resulting in less damp problems (which we have a-plenty!). The RMH will push dat dewpoint even further out as the inside of the wall will gradually heat up.
Taking all that in consideration, I guess the smartest thing is to build the RMH at a distance of about 6" (15cm) from the wall without providing any type of heat barrier. Would you agree with that conclusion? (Me being female = females can't think = wrong conclusion ;o)

2) Building a flue made out of brick. That would be very much like a masonry oven or Finoven as we call it here. However, I thought I read somewhere that brick in these cases would slow down or even hinder the movement of the exhaust gas through the channel because of the irregularity of the brick.
Could that be prevented by applying a continuous, very smooth layer of mortar or refractory cement on the inside of the brick flue in order to minimize resistance?
And finally, how would we be able to ensure that NO toxic fumes would escape the brick construction? Simply by using a solid well cemented construction?

3) If we're constructing the whole thing out of brick and go "up" as per the design of masonry ovens, does this completely eliminate the need for a barrel, or could both concepts be integrated into a construction?

Finally, I have one more question (taking advantage here ;o) and I've enclosed an image to illustrate what I mean.

In our situation the brick flue would run from the RMH over a length of about 6'6" or 2 m to where the chimney goes up through the roof. The actual width of the flue could be no greater then about 15-16 " (40cm) but could go up a fairly long way as it will be situated against a wall.
As you can see in the illustration I've made, I'm not sure what the actual size of the flue with regard to the surrounding bricks must be. Or would there be a set size for the flue, approximating that mentioned in the book by Ianto Evans?

Also, can the exit for the flue from the main construction be situated at the side ninstead of the rear, as most pictures show? Or would that slow down the exit gas too much as well?

Questions, questions ... hopefully not too many or too difficult. As for your remark about "dirty hippies blowing their money on pot" (pun intended ;o) you need to go back one generation for that: Dad even attended Woodstock way back when 



RMH-brick-flue-mass.JPG
[Thumbnail for RMH-brick-flue-mass.JPG]
 
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