Gerry Parent

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since Jan 12, 2017
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Currently live in the middle of the desert where a RMH is not needed but that doesn't stop me from helping others create their own Dragons.
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Kingman, Arizona
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Recent posts by Gerry Parent

Googles images for Canada (especially in the rural areas) quite frankly suck. Old image dates, some blurry and hard to recognize things without already knowing what they are.
Permie Daniel Ray (the OP of this thread) still may be using his and can attest to its longevity?
1 month ago
Any way you could include pictures Austin?
You'll appreciate having them here years from now when you want to review your build and/or help others with their builds :)
1 month ago
Unfortunately, I can no longer share any photos as I no longer live at that location anymore.
Being cement though, I would imagine that as long as it wasn't smucked with a shovel or something, it should be just fine.
From my memory, the second coat was applied within a few days of the first.
1 month ago
Glad to hear the information was helpful.
Good luck on your project!
1 month ago

Austin Shackles wrote:
Question for Matt if he's looking: how critical are the sizes of the spaces around the core?  I assume the hot gases come out of the core, under the top hotplate and then down the side.  I'm still not 100% clear on how the bench connects.  The lower layers look to have 2 openings for bench connection both at the same height?  I need to watch a build video

Hi Austin,   Glad the dream to build a cool stove has finally come to fruition. I'm sure it will provide many years of delightful meals and keep you warm at the same time.
I haven't seen Matt on Permies for quite some time now but can be reached at
which is listed on his website:

Keep us posted on your progress and any information Matt may share with you so that others can benefit from your build adventure too.

1 month ago

Peter van den Berg wrote:The liner in the lower end of the riser is there to form the double vortex properly. Without this liner, the riser box proved to be too wide, only a straight flame was formed. The wider top half is there to provide the gases with room to expand, slowing the gas velocity quite a bit.
So, the double vortex is rising up over the entire height of the rear wall since there's no liner there. Then, the stream curls to horizontal in the direction of the end port which is system size again. In order to reach the end port, the stream has to bend down a bit. This effect will heat up the closed top of the riser more than it normally would do, so the temperature will rise quicker there. The complete path approaches the length of the normal straight riser. The volume of the entire riser box is very close, if not more, to the volume of a normal length straight riser.
The expansion space and the restricted end port together will limit the maximum burn rate of the core, that's the general idea.

Time will tell whether this holds true or not. This is all theoretics at this time, based on experiments with one single, small development model.

Thus far, with about a weeks worth of careful observation of the shorty cores performance, I would say Peters description of what is going on under the hood is very similar to what I have observed also.

The flames rarely have come out the end port even with our biggest fires so far are strongly suggesting that burn rates are being automatically controlled as Peter mentioned.

The bricks we cast are doing very well. No signs of cracking or shrinking. I would feel confident now to light a big fire with no worries of anything happening to them.

The only thing I would change thus far is to use either insulated bricks or superwool to form the entire heat riser. The superwool could possibly be made similar to the 5 minute riser encased in a metal skin, either square or round (while maintaining proper csa)  however, the metal compression frame would need to be redesigned to accommodate this much softer material.

The new door is complete and in full operation.

2 months ago

Peter van den Berg wrote:Sorry to say, most of these type of ideas are solutions looking for a problem. These heaters are radically different from "normal" woodstoves. It's only logical to have a different set of do's and don't's for each type. It did took a lot of work to banish all steel from the firebox' innards, why introducing new steel in there?

Being one of the beta testers of your creation, I don't see any point in veering off from the path you've chosen based on your findings.
Besides, there is plenty of work still to be done in other areas that need more attention rather than trying to fix a potential problem that has not even surfaced yet. Thanks for keeping the ship on course captain!

Peter van den Berg wrote:My solution, which has been in use for 9 seasons now: the fuel is much shorter (about 4") as compared to the maximum capacity of the firebox. I developed the habit to lay the fuel about 2" behind the threshold, so there's a space of 2" between fuel and rear wall of the firebox.
Plus a second habit: In 99.99% of the burns I use the upside-down method to light the thing. For those that aren't familiar with this: the firebox is loaded with the largest pieces at the bottom, the higher up the thinner the pieces. On top of or between the last pieces some kindling and a single barbeque lighter. So there's time enough to adjust pieces before lighting without the risk of scorching hands, and no fuel will be in the port. Lighting on top means the fire is slower to develop, but that isn't a disadvantage per se.

For those whom are accustomed to a specific length of fuel, the solution could be to build their firebox 4" deeper than the fuel's length so there will be enough space. Between the logs or whatever you have, very little space is required. All fuel front to back, no log cabin, tipi or criss-crossing style. This way, the pile of fuel is relatively compact, plus the required space in front, back and top is easy to achieve.

All great pointers Peter. Thank you for fleshing out the finer details.
I can see how for the most part (no matter how efficient or clean burning it is designed) a stove can only be as good as the person tending it.
2 months ago
Seeing as how this shorty core does not have the need for a floor channel brings up the much higher risk of unintentionally plugging up the port with wood shoved too far back or from a falling piece of coal.

An idea came up....Perhaps an upside down U shaped piece of metal rod (approximately the width and height of the firebox port) could be mounted on a plate steel base and positioned about an inch or so before the port? The plate would be sized the same dimensions as the inside floor so it wouldn't move around and (if needed) a horizontal top spacer butting up against the top port brick to keep it from tilting.
Shouldn't interfere with gas flow any more than a stub would.
Yes, metal is going to spall, but still perhaps last long enough to warrant its advantages.
Any thoughts?
2 months ago
Thank you for the informative response Fox.
Have appreciated all your work documenting your own refractory work and advice given.
So far, all our firings have been successful at slowly drying the slabs with no apparent cracks forming.
With the recent warming weather though, we haven't started any large or continuous fires, so time will tell how they hold up in the long term. Would really suck if they decided to crumble or explode after encased in a bell and mid winter! Fingers crossed 🤞
2 months ago
Here's a detail on the refractory brick mold making process that I thought I'd share of what NOT to do.
Seeing that the 3 necessary brick molds were already filled, we had extra mix that we didn't want to waste, so in haste, a shallow metal tool case was quickly emptied and one side had a few clay bricks put in acting as a wall to make it the size and depth we wanted.
The next day, removing these brick 'forms' were not so easy. The refractory stuck to it so hard that the brick sheared a good chunk of it off instead of at its edge.
A masonry grinding wheel was needed to take off this stuck chunk of brick and regain the straight edge we were originally looking for.
Moral of the story is, calculate your volumes before starting out and perhaps have an extra mold ready to go in case excess mix is in need of a home or risk having expensive material be wasted. Also, other than not using parchment paper as a release agent (like we did), be sure to lightly coat each surface with oil as a release agent. One of Peters recommendations is WD-40

On the plus side, we discovered that the metal bottom of the tool case produced a shiny, very smooth surface that reminded me of a granite slab all polished up that if needed to be left exposed, could be an attractive feature.

Question: Bubbles can be seen on the side of the brick. We did vibrate the filled forms until a small amount of water started to show around the edges before screeding the surface. Would it have been better to continue vibrating or will these bubbles pose a problem? Also, when vibrating, we didn't see any bubbles appear at the surface as our mix was quite dry.
2 months ago