John Sizemore wrote:Problems with water would be construction cost. The materials would need to be welded in place and of higher strength.
Moisture. Hot water equals vapor and unless your tank was covered your home would become s steam room.
Calcium builds up in the water tank.
Legionnaire’s disease. It is a problem in hot tubs and other water bearing indoor locations. You would have a petri dish in the center of your home.
Dale Hodgins wrote:I think it would be important to ensure that the water is not allowed to cool the effluent before complete combustion is achieved. Wood stoves with water jackets are prone to creosote buildup if unburned hydrocarbons go up the chimney. The heat riser and several feet of pipe may need to be far hotter than a water jacket would allow.
Dale Hodgins wrote:It would be a shame to have a giant water tank like this for thermal storage only. Water could be drawn off to heat a hot tub and for regular domestic uses.
C.J. Murray wrote:It seems to me that utilizing water as the primary thermal battery for a rocket mass heater has its place in the grand scheme of things. This, naturally, leads to hot water for other needs as well. I am here to be put in my place by all of you if I misspeak so please feel free.
I am very desirous to see RMHs accepted by building officials utilizing cob and other natural materials as a thermal battery. From what I’ve read on these forums there are people who have put a lot of time and treasure into working on proper design. I applaud you for your determination and persistence for little reward. You have my admiration.
It seems to me that part of the challenge utilizing cob is that it is hard to get things just right so that the flue gases exit at the velocity they need to for safe, consistent operation regardles of outside condions and yet not so quickly they carry away precious heat. Since the rate at which water contacts the flue to draw away heat is easy to regulate it seems like that method of heat extraction from the flue gas could potentially make it easier to achieve as near to perfect flue gas exit temperature as possible. I’m not saying move away from cob. I’m saying there may be applications in which water serves the need appropriately. Perhaps a very small amount of regulated water flow could be the final arbiter of flue gas temperature after the cob bench. I’m stunned by the beauty and creativity of the cob creations I see.
Ernie has stated that an RMH can be used to heat water or bench but not both. On the surface that seems to say that a water container can be buried in the cob bench instead of flue resulting in the ability to store a greater amount of heat in the same area as cob and that the cob would act to slow down the release of that heat compared to a steel water container alone. I say it can be a win-win. This then leads to a need to figure out how to best implement that. Seems like a passive system is desirable and possible but…..
Matthias Rascop wrote:1) For passive convection of water you need 2 things: a) Vertical difference in height of of some meters. b) Some serious cross sections (at least 3 inches width) of the piping, two have the water moved by the minimal differences in pressure. You don't need that much flow, because the heat up of 1 liter per minute from 140F to 200F means ca 2,5kW of power. The colder the water gets at the low end, the better for the convection. Generally its possible, but I'm not sure if it can be done with tinkering means...
2) You can basically take every pump you find, because you dont need much power. If you use a sterling engine and a car alternator, possible pumps would be out of the computer-watercooling or aquarium area. Most of them run on 12V, are quiet, efficient, have sufficient flow, and some are capable of continuous duty. I'm not sure, if they are available in the States, but one really good thing for that would be the "Laing vario D5" Its not really cheap, but it'll run, and run, and run...
All illustrations are copyright Ianto Evans or Leslie Jackson, unless otherwise
noted. The text is non-copyright. You are welcome to use it in any way you want,
but please acknowledge your source. We just want people to get stoveing and stop
supporting the utility corporations. It does help our work if you buy books directly
from Cob Cottage Co. or Leslie Jackson. Buy a dozen or a whole case, give them
as presents or sell them at gatherings, classes, conferences, etc. It will pay for your
firewood. –February, 2006
elliott williams wrote:I'm not using a Rocket stove, but I did find this:
It's a wood burning hot tub, where the wood stove is submerged in the water.
I was surprised that the Snorkel said it was 120,000 btus. Can it get hot enough to not smoke like crazy?
I have a tiny home/cabin, 8x24, that I'm wanting to use an exterior stove to heat water for heating as well as hot water uses. We're talking temps much higher than a hot tub, 140+ degrees. I was wondering if a broken chest freezer could hold the water safely. It might need some crossbars across the middle to keep it from bowing out. A 22 cu ft chest freezer could hold 160 gallons of water, over 1300 lbs of water.
Any thoughts on whether a chest freezer can structurally hold water? I'm thinking the long sides would tend to bow out and fail.
Edit: I found this discussion http://ecorenovator.org/forum/solar-heating/809-chest-freezer-water-storage-tank.html He said the 14 cubic foot model didn't bow out. Putting it in the ground with an extra couple inches of styrofoam all around might be an option.
I would want to run the hot water through radiators for heat in the winter and for hot water year round. The hot water would be from a coil of copper tubing in the hot water. An anti-scald valve would be necessary too.
I do have one cautionary thought about using scalding hot water for a thermal mass. It wouldn't take a steam explosion to kill someone, just a rupture or major spill that could scald someone to death. So, safely mounting 1300 lbs of water is one thing, but 160 gallons of scalding hot water is another.