Hot water from a Rocket Stove.

I am currently building a second RMH of which I would like to gain hot water from.
I am considering putting the water jacket around the portion of the J Tube where my main fire is. I have a 1000 pound propane tank converted to a hot water tank. Pumping water through the water jacket and into the water tank. Tank has 4 -3/4 inch openings at the tip to prevent pressure build up.
by suggestions for me?

Thomas Russell : I think you are saying that you will be leaving at least one of those 3/4 inch holes un-capped so that you have an open system and can't have a
build up of pressure at your 1000 gallon tank, actually If the tank is still serviceable I would swap it for a 500 gal tank ! You will want that tank indoors and insulated
and even a 500gal tank will take up lots of room, also that unused 3/4 inch opening must be piped to outside to handle the high levels of moisture vented off of the
system constantly !

The first problem is the amount of cooling of your fire that will occur on start up, As your maximum water temp is 212 dF you are going to be running your rocket way
too cold and producing creosote, this creosote will coat the fire side of the Water Jacket just like the outdoor wood fired boilers we all love to hate! Eventually that
creosote will get so thick that the top layer is above the ignition temp of creosote, at that point two things will happen 1) you will not have enough Oxygen to efficiently
burn your wood fuel AND the creosote too, and you will have a very black smokey fire that will rain charred creosote embers all over your neighborhood with a chance
of fire! 2) the Creosote that does not burn up will melt, running down to the bottom where it will pile up by gravity, and block or partially block the flue pipe causing the
fire to reverse itself and try and vent out of the Feed Tube opening ! Smoke in the house ! Do not attempt to pour water on it, a tight cap on top of the feed tube -If
left there until the entire system is stone cold will stave the fuel of oxygen, bout just like the Movie 'Backdraft' lifting up the cap 'to have a look' will cost you all the hair
on your heat and could even potentially burn your esophagus, causing you to suffocate !

My best suggestion is to consider wrapping a large diameter aluminum coil around the first 6' feet of the horizontal run of the Exhaust pipe as it runs through the Thermal
Mass !

Try making a sketch-up of your plans and we will try to help you find the flaws, Designing hot water heating systems from scratch is a job for a professional and Is not
to be considered lightly ! For the Good of the Craft ! Big AL

Correction i am using a 1000 pound propane pig for a hot water tank. Sorry i cannot swap it as this size is very hard to come by.
Thank you for the information well appreciated.
what happened to the Rocket Stove that was made by wrapping the copper tube around the top of the J tube? Same results?
The last RMH I built I wrapped 3/8's copper tubing around the outside of the outside drum but it only achieves 106° F. Which is insufficient.
I have this system in my greenhouse, so no danger to family.
I need to achieve higher temperatures in order to warm concrete floors. Also can anyone advise me how to upload a diagram to this???
Sorry but I am not so computer literate. I can however try to learn.
many thanks

Thomas Russel : I hear you on the computer literacy issues, Basically, you CAN wrap A large diameter pipe around the outside of the drum and use a circulating pump
to greatly increase the temps you can get off of the Barrel !

There is a natural tendency to want to show off your D.I.Y. masterpiece 'L@@K what I have Done', certain drawbacks and problems with the system are ignored by their
creator in the first flush of creation and ownership ! I would say that it is time for the appearance of another Fellow Member with his attempt !

The folks at homeland security have drilled into the heads of the American public that 'they have to be right every time' the Black hats/bad guys only have to be right
just one time ! I would accept as a Safe working model only what I had personal experience with for at least a year !

Along those lines, You-Tube is filled with crap ! They are so hungry for video content that they will publish anything! A single video-not a series of videos- is a warning
sign of crap ! Also sites with out of date comments, no comments,or comments blocked by the original poster are a sign that the Creator has gotten tired of his problem
child, and is off chasing the next shinny Bauble !

Any system that has a circulating pump should have a 12-24vt back up circulating pump plumbed in parallel with the primary pump, and the 12-24 vt pump should have
its own set of at least two large car batteries with a dedicated trickle charger this should get you through 48-60 hrs of '' being Knocked off of the Grid ''!

As a fast but only partial answer to your question consider going to Solazone.com.au/solar-hot-water/low-pressure-solar-hot water/ I picked this system as
being the most simple one I could find, the system you finally find that you can use will almost certainly be a modified low pressure solar water heater circulating unit !

Note that in this system the holding tank is placed at the highest point in the living space to allow thermal syphoning to carry all the hot water to the holding tank without
pumping and the holding tank then supplies the hot water to the various faucets by gravity !

Again let me say that you can have a Rocket Mass Heater RMH that heats hot water, a holding tank that acts as a large Thermal Mass and supplies you with near endless
hot water ( Even with an 8 or 10 inch system, you will be dancing attendance on this system to the exclusion of other tasks during much of a heating season !) But by the
time you have taught yourself to run this system safely, starting out from a simple low pressure solar hook-up it will take 1,000s of hours if not years ! Big AL

I will try to address all your topics. I read and research topics to great lengths that's how I found this forum. I do not believe all that's 9th the Web as most of it doesn't work.
I am retired and went through a bout of cancer and repercussions so now have time for these projects like.
I am not looking for any pats on the back to what I am doing as I consider myself a beginner when it comes to these things.
I do however post on Facebook pictures of what I am doing as I get advice from all over the world the items to improve some of the projects.
However when it comes to Rocket stoves there is very little good advice. Lots of cap.
I am thankful for the information that you shared with me. Probably just saved me a couple of hundred dollar bills. I don't build out of crap.
I have a very good supply of uncertified 100 pound propane tanks but the rest of the parts I buy from a steel shop.
Later tonight I will look up the sites 5th at you shared with me. My system has a pump and it will thermosyphen as well but I used PEX between the
copper tube and my tank without the pump it gets wildly hot and PEX will only stand temps to 200 °F.
Please keep the information coming and I will try to find out how to post a diagram for you.
Many thanks

I went to the site that you suggested and will return to it later.
I used a 1000 pound Propane pig for a hot water tank as it was donated to me. I welded three 3/4 inch steel nipples to it and added two pumps of which some young Engineer guided me on what to buy. First nipple outlet goes to the pump then to a header which currently is feeding three zones. the second pump / pumps water from the lower end of the tank though 1/2 inch copper line which is loosely wrapped around the outside of a 100 pound propane tank which is the outside of the current RMH that I just built ( my second attempt as the first was a disaster) I can get the water up to 106 degrees F. but this is short of what I am trying to get. I would questimate I am heating 65 to 75 gallons. The main problem is that the in feed burn chamber of this rocket stove is 5x5 inches and only burns for 25 minutes per burn. I am trying desperately to extend my growing season into November. Starting it back up on the end of February.
This is Edmonton Alberta and it gets cold. My greenhouse sits on 6 inches of concrete which is a good heat sink if I can heat it.
I hope that this clears up to you what I am trying to do . I need longer burn cycles and hotter water.
Suggestions and guidance are always welcome!

Thomas Russell : Like you I have gone through some challenges, and live with the repercussions , And time and place often create difficulties with using the Net !

It has been my past experience that Facebook is a better place to see the real guts of a D.I.Y. project then is You-tube, it's a little harder to get away with fooling
yourself when your peer reviewers are Framiley !!! - So if you can post to facebook posting to here is the next step.

You are definitely going to need to both increase the size of your RMHs internal plumbing To get the BTUs per hour that you are planning for, larger diameter tubing
around your barrel or your horizontal exhaust pipe as it is entering the Thermal Mass will definitely help you to extract more heat Insulation at the barrel increases
contact time for heat transfer, but you end up fighting the need of the Barrel to radiate off enough heat to guarantee the push me /pull you effect that allows for the
super efficient burn and the horizontal flow of the RMHs Fire !

There is a separate class of RMH that can be made that allows Batch loading and burning of the wood fuel, and it can be VERY Close in efficiencies to a Regular RMH
with that style you can go longer between loading your rocket, but you are still committed to being close to home All the time you have a fire in it !

Your name will be shared with Fellow Members who can help ! For the craft ! Big AL !

http://donkey32.proboards.com/thread/1096/hot-water


https://permies.com/t/32099/rocket-stoves/doubling-power-RMH-cooling-feed

Thomas, 5x5 isn't much. it's either time to rebuild, an 8 or 10 incher, or go batch, i you don't mind a smidge of smoke.

I'm sorry, but being dumb, and french, i struggle sometimes reading lenghty posts, and i understand better when there's pictures.

I started out with a 8 inch system couldn't get it to pump the smoke outside but sure could blacken the inside if the greenhouse . I could not see 6 inches in front of my face.
Currently I am working very slowly on a system with 1 complete 100 pound propane tank as the feeder tube. Before I continue too far on it I want to listen and see what I can learn from you folks.
I know how to upload pictures to face book/ can any of you advise me of the steps to up load pictures or drawings to this page.
I sure would like the feed back on what I am trying to do. I have as many 100 pound propane tanks as I need and I have been donated a 250 gallon diesel truck tank so I can have more than one insulator tube on the inside before the exhaust has to exit.
However advice is an asset to have from those who have experimented and have got it running up to par. I have spent a lot of dollars on a complete failure and do not want to go done that road again. I bought and installed a double barrel stove with a horizontal chimney and you should see the creosote it could produce. I have it apart just waiting for a trip to the dump! Would like to make something that works. I have a pellet stove but at $5.99 per 40 pound bag of pellets its expensive. I also have natural gas as a back up system for the hot water tank and that is not so expensive. need advice on how to make a longer burning system
Many thanks

Late note : Below I made a sweeping general statement that a metal Feed Tube was always bad, the type of Feed Tube with P-channel as pioneered by Peter van der
Burg is self cooling and does not have this problem ! Sorry, Sorry, Sorry, and thanks for Catching it Cindy M ! Allen lumley Big AL



Thomas Russell : All areas of the Rocket Mass Heater RMH must be sized the same, which you have proved with your working Unit ! I have not seen your previous
build and can not offer any suggestions beyond noting that one of the most common problems for the RMH is not being generous in sculpting enough room for good air
flow at the transition point where the vertically falling exhaust gasses leave the bottom of the barrel and turn at a 90 degree angle to flow into the horizontal chimney
and thru the Thermal Mass ! It could have been as simple as a poorly fitting clean out cap, there was nothing magical about going smaller, indeed it gets harder!
You just had better luck with your next attempt !

One of the few absolutes for a conventional RMH is that the Height of the Heat Riser must be 2Xs the Length of the burn tunnel and 3Xs the Height of the Feed Tube!!!

When you use a metal Feed tube -as the entire RMH comes up to temperature- its metal will act as a heat sink and turn into a second chimney, and Bobs your Uncle,
back to smoke inside your structure !

I have seen wire contraptions that looked like tomato cages turned over and used to channel longer lengths of wood down into the feed tube, this can work if you are
still close enough to monitor the RMHs fire by the sounds of the Rocket ! however larger and longer pieces do get hung up and your first warning of trouble may be
smoke !

Also you have a problem with the freaky high Temperatures we find within the combustion zone of an RMH, (1000dC or 1832dF! ) We are creating perfect conditions
for High Temperature Hydrogen Attack, also known as Hydrogen Embrittlement ! Though generally a highly ductile steel is not as quickly destroyed as a
harder steelPropane bottles can show fatigue or total failure within a single heating season ! You Can Google Search the two terms !

Enough take a couple of deep breaths and take a break,you are already a Rocketeer and your fellow members will help you move on to the next stage on your journey
Big AL

When you use a metal Feed tube -as the entire RMH comes up to temperature- its metal will act as a heat sink and turn into a second chimney, and Bobs your Uncle, back to smoke inside your structure !

This does not happen with Peter van den Berg's design which includes the P-channel which both heats up the secondary air and cools down the metal feed tube.

Cindy Mathieu : Sorry ! and Thanks for the correction ! Exception noted, Actually I think I am guilty of this mis-statement before, thanks for catching it for me/us !

For the good of the Crafts Big AL !

Thomas Russel : You made a generalized statement about me saving you money on your project, and bad luck with previous attempts !

I can not express strongly enough that everyone who wants to build good working Rocket Mass Heaters RMHs, Should start off by going to - ->

rocketstoves.com to ether downlod a PDF Copy * (or get the book mailed to you) of Ianto Evans' Great book 'Rocket Mass Heaters '
This book still has much to teach even a successful RMH Rocketeer - And he can then Be Sure he is using the same terms to describe the size'
shape, and physical orientation of parts to the whole unit, and each other, Everyone who reads 'The Book' will get something new out of it and
it truly will save any D.I.Y. Builder Time, money, and frustration ! For the Good of the Crafts !




*The Pdf download is a simple task, if you have grandchildren, they have learned this trick, you merely need to let them start the set-up and
then Show you the key strokes You will have to make ! You Do have to stress to them that, they are not to do it for you, they have to show you
how ! Perhaps again and again!

Our local librarian could not turn a computer on 5 years ago, now she often helps our libraries patrons with quick work arounds for their
problems, a phone call expressing that you might like to sign up for a future course but need help now, may get you an appointment to see it
done on the Libraries computers Hope this was helpful and timely Big AL