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Using RMH for Aquaponics trough system

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This is a great site. Thanks to the folks that make it happen. And thanks to those experts who admin this forum. We are very excited about RMH and trying to determine if we could use it in conjunction with our upcoming Aquaponics setup.

The basic design idea I have is to build a rocket stove and have the pipe that would normally go into the thermal battery go through a bed of sand that lies beneath a 4' wide 10" deep trough of water. The trough is where the plants will be grown in the system.

We live in southern WI. Think burr for you folks in CA or FL. Think mild for you youpers in the UP and northern MN.

Anyhow, I learned last winter in our test AP system that heat was necessary. Our new system will be housed in a 21' x 75' greenhouse. Well if there is anything less efficient on the plant than a greenhouse with a thin wall of plastic between the inside and outside, I don't believe I have seen it. It seems environmentally unsound to blow heat into the space through the winter with a traditional heater solution. However, if I heat the water which may be in excess of 500 gallons, I believe this is a tremendous battery.

I bought and read a copy of Ianto Evans and Leslie Jackson's book on Rocket Mass heaters.

Here are a few questions I have:
- I am thinking of building trough walls with earth tubes about 2' high. Would it be a good mass if after placing the exhaust duct at the bottom of the trough, I fill around it with fine sand?
- I am confused on what type of pipe to use for the exhaust pipe. I get the idea that the combustion chamber should not be galvanized, but can galvanized be used in the exhaust pipe?
- I have not found a definitive answer that the combustion chamber riser could not be class A insulated stainless steel. Can this pipe be used?
- It seems that fire brick is recommended for the riser. Yet, I see some discussion on the use of other bricks. Around my area there are many chimneys that get taken down. Some have what I would guess is a limestone brick. It is not your traditional red soft brick. It is much harder. Are there other bricks that can be used besides fire brick.

thanks in advance for any help or ideas you can offer.

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i haven't done enough with RMH's to give a fair comment , but i can say , don't use Gal products , most chimney/flues tubes are stainless steel..... As for the AP side of things i'd say choose another variety of fish that's more suited to cold , it will only take a day or two of not lighting your RMH and the fish could potentially die unless you have a redundancy system in place which would be hard for the volumes of water you speak of (500gal) i cant see why a RMH couldn't be used for heating i know of a few systems using compost to heat their water...
i have a forge i built and would have the same brick issues you speak of , i chased down some firebrick and use fire cement.... prior to making it i looked up a lot of "home made" refractory products but all largely had the same issue of cracking under heat within 3 years of use , i think the old saying "penny wise pound shy" comes in here as all you will save in the beginning will cost you more in the long run...
I'd say it would be worthwhile the extra expense of firebrick for such a large project you mention.... i hope someone with more RMH chimes in and offers help on the issues i have no experience with GL on your venture
Peace and Love Dave oxoxoxox
Posts: 4154
Location: Northern New York Zone4-5 the OUTER 'RONDACs percip 36''
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Eric :I am still a Newb at Aqua-p, but,Let me take a stab at the Rocket Mass HeaterR.M.H. program, depending on how you were taught to 'run' a greenhouse,
And at certain times of the Year Moisture will be a major issue for your R.M.H., It needs frequent feedings of Small fine split very dry wood to perform at the
very efficient levels it is capable of burning at.

R.M.H.s don't need a lot of attention, but do need frequent attention, so you have a need for the Rocket to be co-located in a very centralized location to see
that it is performing well, and You need to store your Rocket heaters wood outside of the Greenhouse, with a pass-through arrangement to not be trying to
carry in arm loads of wood and be unable to close the greenhouse door at -15F !

Bricks,High Temperature fire bricks, a pale shade of baby shit yellow are preferred,because they insulate the Combustion Chamber/Burn Tunnel, Reflecting
the heat back into the combustion area and Quickly raise the internal temperatures that create the high temp clean burn that R.M.H.s are famous for, Soft
Smooth faced building brick usually an red but kinda orange-ish too, has a long history in being recycled from hundred year old buildings,( and not the harder
sometimes darker red, with exterior scribing) And used directly as stacked and thin mortared parts of the Feed Tube, Burn Tunnel, and as the Heat Riser.
With any heat riser made out of any brick there is a major gain to be made by Insulating around the outside of the Heat Riser with Perlite and Clay Slip, or
Rock wool ! Heat Risers can be made up with 'stove pipe' on the inside and the outside as forms and filled with at least 2'' of a clay slip/perlite mix,

You should consider all your stove pipe to be sacrificial, You can not use metal in the combustion chamber, and in the Heat Riser area you can only use pipeing
as forms for the perlite and clay slip that will burn up in everyday Use leaving the Clay slip and perlite behind as a semi permanent Heat Riser! This is pot a
negative, the 5+ years you should be able to achieve should see you through to a much superior Aftermarket D.I.Y. replacement !

Please go to the Rocket Stoves Forum/Thread " Rocket Mass Heater: Duct burns'' for a discussion on Galvanized pipe And then go to our sister site richsoil.com
and click on the link to Rocket stoves on the home page, this will take you to a set of videos to show you how to prepare your barrel and 1st 4'- 5'of stove pipe
All the remaining galvanizing left on the stove pipe after your Burn has undergone a change in the way it is locked to the pipe and will not outgas more- after the
1st 4' - 5' your standard galvanizing should never get warm enough to be a problem !Hope this helps and was timely ! For the good of the Craft .

As always, your questions and comments are solicited and Welcome ! Think like fire Flow like gas, Don't be the Marshmallow ! PYRO - Logically BIG AL !
Posts: 3790
Location: Kansas Zone 6a
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The constant feeding is an issue, it is easy to lose more heat opening the door than you gain from the stove. At a minimum you need to add a double door airlock. Double plastic and a blower also make a HUGE difference in heat retention (and rigidity of the structure).

Constant heat under the bed is good, but the water is an awesome heat transfer medium so you don't actually need the bench under the beds if you can heat the water anywhere in the loop.

A little lesson in heat from a fire: I built a 55 gallon pocket rocket as a stock tank heater. It was able to take 700 gallons of water from 3 inches of ice on top to bath-water warm in 20 degree weather (0 windchill) in an open steel tank on two loads of wood. And that rocket was not that efficient.

Posts: 245
Location: near Houston, TX; zone 8b
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We have done a lot of R&D on the heating of dirty fish water. We developed a product called Fish Sweaters; it uses a very small (20 watts) pump to move the warm distilled water through a stainless steel coil placed in the fish tank. It uses an electronic controller to turn the pump on and off; it can also switch between 3 different hot water sources (solar, wood-fire boiler, and gas water heater). Our goal is to displace the use of electric wands to heat fish water.

At the moment, it has only been used with a gas water heater. We used it ourselves for our Tilapia last winter and sold a few to other people who had large systems. One of them has 10,000 gallons of water in an unheated greenhouse in Colorado; it was working all the time which overheated the electronics in the water heater. Another used one to heat the water in her floor radiant system and another in the fish tank; she is very happy with them.

Hopefully, by the time you really need it, we will have a way to have the Dragon Heater warm the water most of the time rather than the gas. So, if you want to check it out: www.greenlifeaquaponics.com and www.dragonheaters.com

It's in the permaculture playing cards. Here's the link: http://richsoil.com/cards
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