I've decided to make a mass heater/water heater out of a propane tank. This will be used to heat water at job sites. The tank will be painted black, so that it can be solar heated, when the opportunity arises.
A metal J-tube will be used when heating with wood. The stove portion will not be welded to the tank. It will sit inside the tank and hang on metal bars. Drawing tonight. Picture a five foot tall, metal candy cane.
When not being used at a job site, this unit will reside on a patio, in the city. Wood burning is not allowed in this townhouse complex and there is no secondary heating source. If the electricity fails, it gets cold.
The unit would be fired on the concrete patio outside and rolled in the kitchen door, once it is hot. There's a 1 inch bump.
This tank was found at my last job. I haven't had it tested yet. If it proves to be a good one, I will sell it and grab a scrap tank somewhere else. Otherwise, this will be the tank. I think it will be useful for about 15 gallons of water. That's 125 pounds of water, with the equivalent heat capacity of 625 pounds of cob. Add 40 pounds for the container and we have the equivalent of 665 pounds of cob. Water stores 5 times more heat in a given weight of material.
are you going to use all metal core? if so what kind of metal core do you plan to use and if you are not going to use a high temp metal what steps are you going to do to protect the non high temp metal?
This is what Tim did at the RMH innovators 2015, it was an old electric hot water tank dropped in 50 gallon drum, insulated with a sheet metal insert, j tube entered the top and exited the bottom, we ran the cold water into the bottom then the hot came out from the top, it heated the water really fast when running you could easily heat up any application, using a loop and a non pressurized system, or scale it up to suit the job you need.
It's better to keep your mouth shut and appear stupid than open it and remove all doubt - Mark Twain
The other one is a foot in diameter and about 50 inches tall.
Those will fit on a welders cart. Welders carts have large enough wheels to get over the threshold bump especially if one wheel art a time.
It seems to me the ideal would be to build a fire brick J tube and put a gas heated water tank on top. If it heats water with propane or natural gas it will heat water with pyrolyzed wood gas. The plumbing is there if you want to use the hot water on the job site. With insulation removed the tank will act as a radiator to heat your home or job site.
I definitely want the J-tube to be metal and separate from the tank. This will facilitate one person movement and will allow the tube to be used in any other suitable vessel. I could see using it to heat an outdoor bathtub. Another use could be to heat a very small building. At jobsites, there is often a small room that needs heat. The one that I'm on right now has a sauna which will become home to my younger brother for a few weeks.
The main obstacle, will be getting the chimney going the right way during start up.
Location: climate zone 6b
posted 4 years ago
have you thought about nickel or tungsten alloys that would allow you to get greater temps to the upward bend in your heat riser so you could insulated it to that point and then allow the wood to get to a higher more efficient burn so you can collect more btu per pound of wood? aluminum would not allow you to insulate at all around the aluminum and seems to me would waste wood btus.
they make nickel and tungsten alloys pipes in those sizes that can have operating temps close to 2000F + depending on the quality of alloy.
to me portable means job site work and a more efficient system would allow more work, more money and less time feeding a stove that does not burn as hot. time is money, wood collecting, stove feeding is more work and waiting for water to heat is more money lost.
One idea that has crossed my mind: While water has a great thermal capacity, it is a fluid and so it creates convection currents that allow it transfer heat much faster than a solid material. This means that it will heat up and cool down much faster. If you wanted to slow that process down, what if you filled it with saw dust and the saturated it with water? The saw dust would mostly(?) stop the convection currents while still giving you a thermal mass that is almost equivalent (?) to a tank of pure water. Thoughts?
posted 4 years ago
Scrap that last post if you actually want to use the water as water and not just thermal mass.
Location: climate zone 6b
posted 4 years ago
Jake Parkhurst wrote:Scrap that last post if you actually want to use the water as water and not just thermal mass.
portable job site heater and water heater. I get it... it has to be rough, light and PORTABLE! Portable is the key and to have the work load as desired. in order to get those desires the only set up i can think of is a high temp tungsten or nickel style set up with the core and part of the riser being insulated and clay or brick would not be portable, light or rugged so its out of the question. High temp metals would give you higher temps, higher efficiency, higher ROI on BTUs being burned, higher ruggedness to degradation, higher speeds on water heating and higher amount of job site and money making time not tending to the stove to accomplish its desired workload.
i have posted many links in many other threads that nickel and tungsten alloy pipes in your size are available many places and can be affordable in such a small portable rocket stove. a tungsten only metal pipe has a 6000F+ melting point although pricey alone many alloys can be had much cheaper.
I won't be seeking out any exotic metal. Steel or aluminium are readily available and my welding guy is familiar with them.
A clay or brick protected burn floor is needed, to protect the flame and coals from the cold water. Metal in a water bath, sheds heat really fast. Very thin aluminium kettles are used on gas stove tops and they can last for years. The same kettle exposed to flame while empty, will be destroyed in minutes. The greatest challenge, will be maintaining a suitably high burn temperature.
My jobs produce large quantities of wood, that I give away or pay about $130 per ton to dispose of. Yesterday, I gave away a small pick up load of 2x4 shorts and cedar trim from a demolition project. The day before, I gave away 4 garbage cans of shorts. Stove feeding, will almost always be done during an operation that produces short scraps. I've often kept a wood stove or fireplace going, during the work day. My sites are usually quite clean, as demo sites go. This is because garbage and firewood are constantly gathered. Lumber and other items being sold, are piled neatly. So, there is no fuel cost and minimal labor. The stuff has to be gathered. Some will be incinerated on the spot. If the unit is used during a power failure at the town house, labor and efficiency will not be a big concern. At that point, I will be the conquering hero who was right about the need for emergency heat. In preparing for an earthquake, people store up water and granola bars. Most homes in the city, cannot be heated, when the electricity fails.
I am following this build/idea. The aluminum kettle concept should help people understand. I think you are on the right track. Its also good to be prepared for emergency situatuions, so that's a bonus for sure. Good stuff
John McDoodle has come up with a brilliant source for some higher temp metals he gathered for free i believe. John, why dont you share your nickel ideas and where you got them. nickel is much better than aluminum.
Its not that i am as concerned with your aluminum melting as much as i would be concerned with Galvanic corrosion.
Galvanic corrosion may occur where there is both metallic contact and an electrolytic bridge as in your system with water between your different metals of steel and aluminum. The least noble metal in the combination becomes the anode and corrodes. The most noble of the metals becomes the cathode and is protected against corrosion. In most combinations with other metals, aluminum is the least noble metal. Thus, aluminum presents a greater risk of galvanic corrosion than most other structural
Close-up of galvanic corrosion in an aluminum and steel. The corroded section was held in place by a carbon steel nail. The contact surfaces between the steel and the aluminum were often wet and attack was aggravated by changes in PH, NaCI and temperatures.
Galvanic corrosion of aluminum occurs:
Only where there is contact with a more noble metal (or other electron conductor with a higher chemical potential than aluminum, e.g. graphite).
While, at the same time, there is an electrolyte (with good conductivity) between the metals.
Galvanic corrosion does not occur in dry, indoor atmospheres. The risk of galvanic corrosion is greater in environments also with high chloride levels, e.g. city water and areas bordering the sea.
Problems can also occur where the metallic combination is galvanized steel and aluminum. The zinc coating of the galvanized steel will, at first, prevent the aluminum being attacked. However, this protection is reduced with high temperatures and disappears when the steel surface is exposed after the consumption of the zinc.
As it has a thicker zinc coating than electroplated material, hot dip galvanized material gives longer protection. Thus, in combination with aluminum in aggressive environments, hot dip galvanized material should be used.
It's one thing if you build an all aluminum system but once you start using water, and other noble metals you run the risk of aluminum galvanization and deterioration of your aluminum heat riser from the water side in.
I never thought about galvanic problems. This means I will use steel.
Another note. All of my wood heated water schemes, past and future, are open systems that simply boil water away if overheated. There is no way to make them explode, since the vessels are vented to the atmosphere.
Both tanks will be painted black, so that they will better absorb sunlight. I have a large, clear plastic bag that fits the smaller tank.
I still haven't checked to see if the tanks are salable. When I returned to my old job site yesterday, they were not attached to the house. Naturally, I thought they had been stolen, but then they were found in the garage with the asbestos bags.☺ A hazmat company had disconnected them in preparation for disposal. Their scrap truck showed up half an hour later. That's cutting it close.
The smaller white tank is the one that I plan to be portable.
If the large turquoise tank is not salable, it will become part of a building with a small pond beside it. The tank will be mounted in the highest part of the roof. A bread box style, solar water heater, will be built around the big tank. It should look like a coppola sticking through the roof of the short garden bath house.
A cold tank of water can absorb a lot of heat. The sun will provide all or most of the heat, from April to September. Even in the dead of winter, water pumped up in the morning, will warm a bit, by the time a fire is lit in the evening.
A J-tube or batch box made of insulated firebrick, will have an exhaust pipe that passes through the large tank.
Beneath the tank, there will either be a large bathtub, or a very small hot tub. There will also be a shower.
Water will be pumped to the tank from the pond. After the water is used for bathing, it will pass through a small wetland, on the way back to the pond.
The big tank weighs 272 pounds empty and will hold about 80 gallons of water. When fully loaded, the big tank will weigh approximately 1800 pounds. I anticipate resting it atop a large gabion pillar 3 feet in diameter and 7 ft tall. The pillar of rock will be a large part of the building's thermal flywheel.
All of this is contingent on these tanks not having a market value. If they sell, similar tanks destined for the scrap yard will replace them.
The tub in the last photo, is large enough to hold at least two average sized humans. I've never convinced more than one woman to bathe with me at the same time, but one can always dream.😎
Location: climate zone 6b
posted 4 years ago
I want to say good luck with your system.
those tanks are worth a few bucks. also keep in mind those tank will eventually rust out. you may get a few years use out of them.
please give me your word that you will take the pics of the steel in your stove When it breaks down and post them here.
if you cant fit more than one other person in there make sure you set a size limit before they get in?
Only one woman at a time? I've been having that same woman problem lol. Anyway aluminum doesn't rust, but it melts and it corrodes if its near steel. I encounter that a lot at work when steel bolts are siezed into corroded aluminum. Steel will also degrade depending on tickness, temperatures, oxygen levels and all that, however I'm using steel in my first rocket prototype structure, that means I will need to protect the steel in very hot areas and in low oxygen areas I think. I have heard the warnings from many who have been down that road, so I lined my riser and I'm lining my burn chamber with snug stainless steel liners. Nothing restrictive as that would also cause issues. One of my pellet burners is fabricated from hi temp hi-nickle exhaust pipes. So far so good, but be prepared for negative feedback when using steel or aluminum, and be ready to replace parts or at least protect the hottest parts. Both of my liners are replace-able if they ever degrade.
Nice tub! Two people is probly enough for that baby anyway.
I've been pondering ideas I had before with a large propane tank for the barrel/base, and all cast refractory J-tube/riser.
Anyway keep up the updates as you progress.
I wanna know how many good women fit in there
I anticipate using a water appropriate coating on the inside of the tank and on anything added to it. The top will be removed, so that there is a hole 2 ft in diameter. Regular inspection required. The painted metal should never get much hotter than the boiling point of water. I'm thinking 1/4 inch thick tubing. An excavator lives on site. If maintenance is required, the top glass of the coppola could be removed and the empty tank craned to the ground.
Perhaps the chimney running through the tank, should be attached using a high temperature gasket, instead of being welded in place.
F Styles, Dale is planning to insulate inside his steel J-tube with refractory material; also, the steel will be immersed in water so will be unable to ever get really hot. Any deterioration will most likely be in the form of the steel rusting rather than heat degradation.
Location: Victoria British Columbia-Canada
posted 4 years ago
Another function will be as a washing machine. This will be done when it's solar heated.
Heat degradation should be nonexistent. Rusting will be kept to a minimum through some sort of coating. The j-tube will only be inserted in the water when in use. Most of the time, it will be completely dry.
The tank will probably receive more solar heating than J-tube heating.
It will sometimes go inside my sleeping pod, which is being sheeted in hard greenhouse plastic.