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Post by pinhead on Sept 25, 2017 14:45:50 GMT -8
The heat riser must be insulated. Wrapping the riser with mass will be a detriment to performance. If you're building the riser using insulating firebrick, you can wrap the brick with relatively cheap insulation such as mineral wool or rock wool.
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Post by n8ivetxn on Sept 25, 2017 21:12:37 GMT -8
Oh, I did the same thing you did - lined the inside with 1" ceramic fiber blanket, you may not be able to see it in the pics..... Here are a couple that show what I did: www.flickr.com/photos/158311195@N04/Next, I'll brick around the riser to stabilize it and fill in the gaps with something like cement or ....? I can't afford to buy a lot of perlite to mix an insulation for the exterior riser, I'll have to come up with something a little more affordable... For the bell, I'll brick over the entire riser. I'm contacting a couple of people for a barrel to make the riser. More pics tomorrow....
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Post by pinhead on Sept 26, 2017 4:41:47 GMT -8
Ok I see! I had a relatively small space between the riser and the back wall of the bell so I stuffed some rockwool in the gap to help stabilize the riser while further insulating the bottom half of the riser (never hurts). Wire or Plumbers Tape could be wrapped around the riser and attached to the firebox somehow as well.
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Post by n8ivetxn on Sept 29, 2017 23:30:48 GMT -8
Update: I got my barrel and tomorrow Hubby will cut it up for me.... I cast a perlite/slip top for the firebox. I added a few more photos: www.flickr.com/photos/158311195@N04/Sometimes it takes a while for things to click with me, and last night I had an epiphany. Before last night, I didn't quite understand how the whole firebox assembly was supposed to come together: the floor channel, primary air, threshold - for some reason I had failed to "get it." After reading through some of Peter's old posts last night, it suddenly clicked. Now I have some mistakes in the firebox opening. - I've been unable to find a welder to fabricate the floor channel, so I've had to improvise. A man at the hardware store suggested the 2 small copper pipes with elbows, laid side by side. He said the copper should stand up to the heat. They are 1/2". - Since I failed to make a proper channel below the level of the floor, the best I can do is to incorporate the copper air tubes into the existing floor and add some slip to raise it some, in essence recreating a higher floor. (- does all that make sense?) - I failed to build in the primary air gap at the threshold. So, I think the best I can do is to take an angle grinder and bevel the front edge to create a little air gap. Or, maybe I can add some mortar to the front of the box, effectively extending it out just a bit and creating a gap. I hope to have this thing finished soon, even if it doesn't get cobbed up immediately - the temperatures will be down to the upper 30's to 40F very soon. My plants won't take that very well
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Post by peterberg on Sept 30, 2017 0:20:51 GMT -8
Those two copper pipes are waaay too small. The tested cross section area is 6.4 times as large as what you plan to use now. There's also the vertical part to consider, where's that?
I spotted also another potential glitch, as I see it the port is flush with the back wall. This is a mistake, between the back wall and the port there should be a distance of about 1.5 times the width of the port. This seems trivial but test results demonstrated unmistakenly a cleaner burn this way.
Just to be sure: the port should be in the very center of the riser as well, otherwise the double vortex phenomenon won't occur.
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Post by n8ivetxn on Sept 30, 2017 8:37:18 GMT -8
Hi Peter, thanks for the insights - I knew the copper pipes were too small, but it was the largest size they had in cut pieces, so I went with it. Maybe it's better than not having one at all? When I originally put it all together, dry, I did have the port moved up from the back wall, but I could not remember why I was doing that...so, in the end, I bumped it to the back wall.... The port "should be" lined up well with the riser, I say "should be," but I could easily be off a little. Well, if this gets my plants through the winter, maybe next spring I can take it apart and rebuild it - correctly! Thanks for helping!
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Post by n8ivetxn on Oct 2, 2017 20:13:08 GMT -8
Just as I feared, the riser is still really close to the rafter. I canted it off to the side, to avoid the close proximity, but it's still too close. If I go ahead and add a 1' gap over the top, it will be mere inches from the rafter and polycarbonate sheeting. The only thing I can think of, is to mount a sheet of Hardi plank to protect it. Not sure how effective it would be. www.flickr.com/photos/158311195@N04/I used the last of my mortar today, I'll have a new bag Wednesday. Finish and fire it up! I must be allergic to the refractory mortar. Part of my face and scalp are on fire, my ear aches and jaw is all swollen - like I've been attacked by stinging insects! My joints ache like the flu. My eye has been swollen, almost shut and drains continually. Never in my life!
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Post by Dan (Upstate NY, USA) on Oct 4, 2017 12:59:02 GMT -8
The concrete block is going to crack after a few firings, that concrete block was not made to be heated up and cooled down that fast without being lined with some fire brick.
Eventually it will crack and you risk carbon monoxide into the greenhouse!
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Post by Orange on Oct 5, 2017 11:50:23 GMT -8
and for the bottom you can use Ytong blocks instead of concrete, that way heat doesn't leak into ground much.
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Post by Orange on Oct 6, 2017 6:17:05 GMT -8
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Post by n8ivetxn on Oct 6, 2017 11:30:25 GMT -8
Thanks guys, I appreciate the info... Yes, I knew the concrete wouldn't hold forever, I just couldn't find any clay bricks within driving distance of me. So I used the firebrick for the most intense parts and concrete for the rest. Most likely, I'll have to pull this apart and rebuild it next year. Maybe I'll be able to use more firebrick and find some clays before then.... I don't think I've ever heard of "y-tong blocks," are they common? This allergic reaction has been awful. My left eye is still swollen shut and my face and scalp are blistered and scabbed I've never been allergic to anything in my life! I had to stop work altogether until I can see again. I have help now, for the mortar stuff! - I haven't handled the ceramic fiber very much, but I'll keep that on the "suspicious" list..... We plan to have this thing running by Sunday night or Monday. I don't really need to have a huge blaze in it. Maybe it'll last a season. I'll post some more photos soon, thanks for all the advice ~ Rita
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Post by n8ivetxn on Oct 6, 2017 17:56:11 GMT -8
I think I'll place a good quality CO2 detector in the greenhouse.....
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Post by n8ivetxn on Oct 9, 2017 22:58:27 GMT -8
Results: It works! Fired it up last night...it smoked a bit at first and then took off The outside temp was about 36F last night, the greenhouse stayed at 54F all night! Here are the last few pics: www.flickr.com/photos/158311195@N04/It is a homely piece of handy work! My hubby couldn't believe I did this alone He's been away for a bit. He said if he'd known the scale and scope of this project he would've bought me the correct fire bricks needed to build it. He was really excited to see it work.... now he wants to build one in his shop!! I learned a lot from y'all, thanks so much for the direction...next time I'll get my mistakes corrected and it should run more clean and efficient. ~ Rita
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Post by pinhead on Oct 10, 2017 5:54:15 GMT -8
Looks good! Do you know for how long the stove burned? Did you happen to take temperature measurements anywhere on the stove?
I'm really curious how well the cinder block primary bell works and holds up.
Are you going to cover the lower (half-barrel) bell with cob?
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Post by satamax on Oct 10, 2017 18:09:15 GMT -8
Cool!
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