Shop rocket heater

[metalmole]

Hi all my first post...I have a workshop that's 20x28 that I am going to build a rocket heater for. The bell I am using is 15" in dia. and 28' long ( its an old LP tank ). I am going to use square tubing of .125 or .187 thick ( which ever I can find ) I was thinking of using 4" for the wood feed, burn chamber and riser tube ( I might use thicker for the burn chamber ) I'm not planning on insulating the riser tube at first in order to get this thing going as quick as I can. It will be a down feed design, been checking lots of videos on you tube and seems the type I am thinking of building works  quite well for a work shop heat source....any comments and thoughts......thanks   

[satamax]

Metal for the innards is doomed, and not insulating it means it's no rocket!

[metalmole]

So it wouldn't work at all for a quick one season of heating ??, im not looking for the mass part, just a way to get some quick heat in the mornings so I can work in my shop....

[satamax]

Well, i've used metal before for teh heat riser and burn tunel. 14 burns later, and it was dead.

This one works well in my workshop. donkey32.proboards.com/thread/849/green-machine-inch-tube-help It could cope with a bigger bell. You could do a partial metal construction. If you're absolutely sure, i could draw something. But i don't want to waste my time.

[metalmole]

Thanks Max for the link to your workshop heater, Yes Im sure I am going to build some sort of rocket heater for my shop and Im sure I need some advise from others who have made ones that work...Im not dead set on making it entirely from steel, the reason I was thinking steel is I have a metal fab shop with all the goodies to work with...Looking at the pictures of your stove I am now convinced I need some sort of insulated burn chamber and riser tube....I have worked with refractory cement and ceramic blanket building a metal forge.....looking forward to some advise and direction....

[satamax]

Well, if i was in the position of redoing a workshop one.

I would do a metal box 75cm x 75cm x 180cm tall. Put that on four legs of about 30cm. cut a hole for the firebox. Make a metal box lined with insulating firebrick. In the shape of a batch rocket. And fit a refractory flue liner at it's end, to make the heat riser; with a metal tube around (gas bottles work well for me. And fill the space in between with vermiculite or perlite. Even if the flue liners crack, the packed dry lose insulation hold them. There's some pics of in progress green machine, in the adventures with a horizontal feed thread.

[satamax]

Icarus has posted this, which isn't far from the idea i was speaking about.

home.earthlink.net/~153maps/110613.html

[metalmole]

That's a nice stove Icarus has built, I was trying to build a stove with a smaller footprint, my shop has a limited amount of room....Look at this stove this guy has built, looks like a nice smaller design... www.youtube.com/watch?v=q2eJec82D3I

[satamax]

Hi Metalmole. Well, his thing is too small. There's not enough radiating surface for heat extraction. Ok, daft me, i thought you had a 5600sqf shop, when it's 560'². My conversion into square metres is lousy. So i was gone astray. I think, do a six incher batch. J tubes are fiddly.

I think a 20"x20" column could accomodate the heat riser and part of the batch box. The general consensus is 50sqf of internal surface area for a 6 incher. But that's with a massonry bell. I think with metal, you could go smaller. Tho, if you do 20"x20" by 2m tall (aproximately 78") you have already about 4m of radiating surface, or 40sqf. That's small footprint. Tho, enough for extracting heat.

For the batch box, you can do like the guy has done in the video you've showed, metal on the outside, insulating firebricks on the inside, metal box to hold them. With about twenty bricks you can do the firebox. For the heat riser, have access to refractory tubes in Italy. Which you might not find on your side of the pond. Ask Matthewwalker for one of his risers.

walkerstoves.com/products.html

And please, read this thread donkey32.proboards.com/thread/511/adventures-horizontal-feed?page=5

If youre on your way, set on this idea, i'll draw it.

[endrunner]

Here is a link to a quick and dirty greenhouse shop barn mass heater that we just did.

Data Logs for a 3 hour burn and 6 Heat Loss Track are here..
blog.dragonheaters.com/derrick-8-rocket-masonry-heater-part-2-data-log-3-hour-burn/

[metalmole]

Thanks Max for the thread, im in the process of reading through it, I have decided to do the horizontal batch box like most of the stoves on the thread, and to make it from fire brick or the clay chimney liner like you used, like these www.oneontablock.com/claychimney.html I will also use a refractory type heat riser, I might make it from round clay chimney liners, I need to do some more research. What do you think....

[peterberg]

Metalmole,
Those chimney liners will crack, unless you divide those in two lengthwise. Use superwool or equivalent as a gasket and tie them together by means of some steel wire or thin stainless steel hose clamps.
The lower part of the riser, right behind the gate is the part which will recieve the highest thermal stress. The chimney liners aren't up to 2200 degrees Fahrenheit, so you have to use another material with better specs there.

[metalmole]

Thanks Peter for the info, would it work to make the lower part of the heat riser from fire brick to a certain height and then use the clay liner ?? What about using the clay liner for the batch box, I don't wont to cut any corners and have this thing fail on me....

[satamax]

Hi guys.

Well, metalmole. Been thinking bout you. shopstove.skp (164.11 KB)

Peter, i know the CSA isn't respected all the way, and there's some funy points, like where the heat riser meets the end of the burn tunel.

Metalmole, i haven't drawn the Peter Channel Just cos i have spent enough time on this. And you can work things out yourself.

A little metal box, a big metal bell. Onto which i haven't drawn the top, nor the outlet, which should be near the bottom. Dry stacked insulative fire bricks. As few cuts as possible. I've drawn it with a dimension i have, but doesn't seem to exist commercialy anymore. So adjustements will have to be made. But i think it's the simplest way to build one. You could narrow the firebox a smidge. Tho, mine is about that size, it smokes back every now and then, but i have about 8 metres of horizontal pipe and a restriction. Plus some is underground. With a far from ideal chimney. Etc! If you exit directly up after this, you don't have to worry, you could even power a little bell or some mass. Fill the four corners between the firebricks and the metal box with some rockwool or something to stop leaks from there. It doesn't need much. On mine, i've used one to make my P channel.

I don't know about your flue liners. What i'd do, stick one or two, whichever lengh you need into another tube, about two to four inches larger than the liners outside diameter (depending on insulation). Fill with loose insulation in between. I've used vermiculite. And if it cracks, be it. Or even splitting like Peter sugjests. Tho, being me, i wouldn't even bother puting a gasket in between. The vermiculite outside would stop enough of the gasses from comming into the bell. And even then! That doesn't matter much.

[peterberg]

Metalmole,
You could use metal for the firebox like Max said, and line that with superwool insulation and split firebrick. The same could do for the lowest part of the riser. That isn't easy to make round, but octagon is a pretty good approximation. Even the higher part of the riser could be made like this.

You could use stacked barrels as a heat exchanger. I've done that in my workshop and it do provide quick heat. No problems to keep it going, when the roar stops it's time for a refill.