Scott Weinberg

Von Xiong wrote:Hey all! In the next week or so I need to build a 8 inch batch box and I need the design template. Where can I get it?

Von, Looks like you started two different threads searching for the "answers", with Dragon Tech already giving you the dimension basic page.  Depending on the details, you would have much to do, before NEXT WEEK, depending on what you have available.  Along this line would be some questions to be answered only by you.

- fire brick size
- bell brick size, single layer bell or double, with bench or not
- extended batch chamber or not
-  standard batch with riser, sidewinder, or perhaps the latest, the shorty
- right, left or rear exit flue
-raised burning unit or base level
-size of glass on the door or no glass at all

This is not to discourage you, but rather helping you to formulate your game plan as these stoves are rather perminate in nature, and certainly can't be moved once done.  Best of success.

Robert Ray wrote:I don't have a RMH, but I do want to try a sand battery heater in the green house.
My test will be creating a sand battery 2ft x 2ft x 12 ft corrugated sides, to simulate the mass of a RMH Two courses of bricks at the base, the remainder will be filled with sand.
I picked up the bed materials today from Home Depot. Spent some time with Jeff Besos ordering heating elements from Amazon today.
My experiment will be placing the different elements within the central 4 feet of the bed.
The heating elements I ordered consist of a broiler element, a water heating element, an industrial immersion heater, a clothes dryer heating element, an eight inch stove top element, 6 PTC elements. So about 150.00 dollars worth of different heat sources that will be placed within that central 4 feet of the 12 ft bed. .

That is fantastic and sounds like you will have a excellent systematic way of testing the results.  I am sure there are many that will await your results. Please do keep us informed.  Best of success!

I know it has only been a few days, but did anyone decided to heat up their sandbank with excess wattage from there solar panels?

Is your typical panel around 350 Watt with a  typical excess planned for about 3 hours per day?   or about 1050 watts per panel if you have that much excess.

So this is about 3500 btu's gained per panel if you have that much excess or about 3/4 of a pound of wood for heat production per panel

 My engergy coop does not allow for us to install EXCESS production, unless we are off grid.   So we have NO excess that could be harvested per say.   But it sounded like a lot of you, had excess wattage, and figured it would be easyily accebbible,   So I was wondering how the sand was warming, and how warm the sand was getting.  

Would like to see the results.

I am hoping one of the many that support this idea can give the rest of us a report.

Simply take a steel container, a 20-30 gal oil drum seems like it will work for this test.  if your in north east Iowa, I would give you a barrel or three.

Please pick out a location for your resistance wires/rod/element, what ever you want to call it. And please do tell where you put them  in your mass,  And then fill the barrel up with sand.

At this point, plug into your solar panel and let it start charging, (passing voltage to the element)  or if you want, you buy a 110 volt water heating resistant element as many of you stated these are only 10-15 dollars.  Plug it in and let it rip. Make sure you record temp of sand at bottom, middle and top,  And if you like, let us know of which method you used. What size you used and what the dry sand weighs, that way we can easily figure out how many BTUs your bank is storing

Let us know the results after one day, then two days and so on.  Make it scientific, your test could help create world peace.. So this will require nice dry sand as wet sand might be not safe and possibly a bit variable due to temp variations,  sand grade or size would also be nice, so others can duplicate when it works well for you.

And at the end of next week, you should be able to post the results.  I would think sand weight, sand height, and volume will also help.  Keeping it simple as stated on this forume,   would be is very important. No need for switchs, just let the mass storage begin and then report NOT what is thought should happen  but what it really did happen.  

We will wait for the results. and please let us know.

Benjamin Dinkel wrote:I do think Scott has a point here.
Sand is cheap, available and easy to work with.
But it’s also somewhat of an insulator. So apart from the heat capacity (1200 kJ/(m3*K) in sand vs 4200 kJ/(m3*K) in water)the question of how to heat it up is an important one.
I don’t know how the fins took care of that. Maybe pressing air through the sand?
There’s a reason a lot of heat storage happens with water. Not the best conduction either, but when you heat some it rises so your heater can continue heating cooler water. And it has a big capacity.
Is water an option for your case?

Or is your question rather whether anyone ever installed an electric heat source in their RMH mass?

Thanks Benjamin, if I may, I will explain a bit more, where I feel projects go from basics to complex, and maybe I am missing something, but in general, this is often how it goes.

if we consider our base heating system being used  in of the latest stove designs, which heats our mass in as effecient method as we possibly can, and we have proven all over the world that we can do this with NO mechanical means.

From this, we as rocket designers-users-even dreamers, start looking at additional storage methods, thus the name of this thread. Very quickly we note IT CAN BE DONE, but just as quickly find in most cases that it involves, a vast addition of mechanical means.  I bring this up, for one reason only, that being, I was not trying to say it can't be done, but rather if it is attempted, beaware that it can easily approach a level of no return on investment.

All great ideas start somewhere,  I just wish some of these ideas go down the practical path first, then get cleaned up,  Rather than proposing a dream, and spending years to convince others that it just maybe, quite possibly, with greatest of hopes, can work.

Sorta like spending $10K to save $1K, we often see in many simple ideas that have grown into complex ones. Another proof of this is the very often "showed on the internet" technolgies that promise great things, just as soon as they get
1) funding
2) figure out a way to make it work for the masses,
3) more funding,
4) and get technology to let them do what they proposed.  
     This of course is not true in all cases, but is generally par for the course.

Best of success!

Dry sand has proven to be a pretty good insulator, and pretty poor at heat storage,(getting it uniformally heated up) vs brick/stone and other solid material.  Although It can be transportaed and placed fairly easily. that does not make it that versistal for heat storage.  And of wet sand works great up to the boiling point of the "wetness" But that is a whole different can of worms.

Pebble banks, for much of the same reasons. Both have similar claim in that they are easy to build with.

Eugene Howard wrote:So a few observations and perhaps clarifications......



1. Hotter stack temps.......don't stall the engine with too much load?
2. Less stack height? Can recall issues when folks put rockets in basements and ran flues up 2 or 3 stories and they didn't work? So short stacks to chimney top vs tall? Then there would be issues with inside chimney stacks vs. outside?
3. Does it matter if chimney flue pipe is single or double wall?

Seems like there are a lot of engineering variables to consider.......and perhaps some guildelines set forth as something to consider and follow?

I probably sound like a broken engine to those that have followed my comments in the past, but will repeat a few here.

1)  Never have a seen a fire getting to big for the design, basically meaning every design has the "proven dimensions"   for the size of the flue. With that in mind, I would answer, that NO, sized right, you will not stall the engine with to much heat,

2)  Are you calling the flue a "stack" or are  you referring to something else, my flue/chimmeny or maybe what you call stack is 35' plus tall.  So not sure what is meant by something  not working because stack height.  I will put forth that restrictions, will be first and formost the problem with flues.

3) would seem to best study what you need to know about keeping warm air rising.

Again proven ways have been just that, proven!

Peter van den Berg wrote:
But... there is a certain effect that is firmly based on physics, the kind that won't be influenced by faith. That effect is mostly referred to as "chimney stall". About +/- 20 minutes into the burn, the exhaust gases into the chimney need to be warmer than 60 ºC (140 ºF), otherwise the chimney draw will cease to exist and all smoke will stream into the house. What I mean with temperature measurement, is done in the very center of the chimney pipe, where the stream has its highest temperature and velocity.

I would like to praise Peter for his explanation here,  as most of you know, I am blessed  to have tremendous draft 97% of the time, It literally can suck a newspaper crumpled  up right out of my hand and do so even without a fire lit, but a warm stove. I attribute this to Peters well designed batch box that I built a couple years back.

Anyway, if I get in a hurry and rush a cold start, exactly as Peter described can happen. But oh so- I dare say- fixable, with gentle adjustments on the bypass, and in my case, you can hear when it is going well. I never experience the need or requirement when my stove is warm

Well done Peter

Scott

Twice  smoked bone in Ham with pineapple and maraschino cherries.  Ham the way it used to be.