tferr
Junior Member
Posts: 69
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Post by tferr on Dec 11, 2021 13:00:22 GMT -8
Very nice!
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Post by Vortex on Dec 11, 2021 14:53:27 GMT -8
Installed the engine in the bell with a 5/8" round fireplace gasket between the frame overhang and the masonry. Waiting on the 3'x3' 1/4" steel top plate.
1/4" / 6mm steel plate is too thin for the top, it will bow and warp and be very hard to seal. I used it for the top of my original stove and had to weld 6mm x 50mm angle steel all around the edge to try and hold it in place, even then it would bow up so much my kettle would wobble when it was boiling. I'd say 1/2" minimum, 3/4" ideally for that size. I have 15mm / 5/8"+ thick top on mine. |
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Post by treebased on Dec 12, 2021 10:33:18 GMT -8
Installed the engine in the bell with a 5/8" round fireplace gasket between the frame overhang and the masonry. Waiting on the 3'x3' 1/4" steel top plate.
1/4" / 6mm steel plate is too thin for the top, it will bow and warp and be very hard to seal. I used it for the top of my original stove and had to weld 6mm x 50mm angle steel all around the edge to try and hold it in place, even then it would bow up so much my kettle would wobble when it was boiling. I'd say 1/2" minimum, 3/4" ideally for that size. I have 15mm / 5/8"+ thick top on mine. I was afraid that might be the case. The actual hole is 28"x28", the plate will have a 4" ledge to sit on all around. I was planning to use double 5/8" rope gaskets between the masonry and the plate with 3/8" anchors centered between the gaskets at corners and centers. I was thinking of welding some angle in a grid pattern on the top plate to help mitigate any warpage. The top of the box is 6' and I'm a bit lacking in the help department. 1/2" plate at the size I need starts to weigh more than I do. |
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Post by martyn on Dec 12, 2021 11:13:47 GMT -8
Is the plate going on top of the blocks ?
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Post by treebased on Dec 12, 2021 12:02:25 GMT -8
Is the plate going on top of the blocks ? That was my plan, yes. Blocks are poured solid and covered in refractory cement wherever they will be exposed to extreme temps |
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Post by martyn on Dec 12, 2021 13:08:53 GMT -8
Well that means the plate will be 20” above the the afterburner roof, I think the metal might be ok but you can cut a circle hole say 6” in the center and that should stop the sides warping and make the whole top slightly concave when heated, you can just lay a 8” circle with a bit of rope to seal the top. That will give you an access and viewing point to….
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Post by treebased on Dec 20, 2021 15:36:39 GMT -8
It's alive! The first burn was rough, leaked smoke everywhere, big puddle of water came out on the floor under the chimney box, top glass sooted up through the entire burn. I assumed the water was due to the heat driving the moisture out of the bell, I let the masonry set for more than 1 month before the first fire. Re sealed everything and it functioned much better on the 2nd burn. I drilled a small hole in the chimney box and blew fire (propane torch) directly up the chimney to get the draw started, even with that, it still took longer than I'd like to get up to temp. I'm hoping it will improve as the moisture leaves the system. 2nd burn saw less sign of moisture and no actual water. The metal top is 280F in the center according to my meter, the chimney runs nice between 115-135F
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Post by treebased on Dec 20, 2021 15:41:46 GMT -8
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Post by treebased on Dec 20, 2021 16:08:45 GMT -8
1/4" steel top held down with tapcons just snug over a double layer of 5/8" rope gasket
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Post by Vortex on Dec 21, 2021 2:24:56 GMT -8
What a beast  Soot is not enough air, but that can be because the gas flow is too slow due to damp mass. Are you lighting the fuel from on top, primary air full open? Your chimney temps are too low, you want 140f minimum. Are you lighting small fires to dry it out? At those temps you will get condensate forming inside and leaking out the bottom. What's the ISA? Your V-floor is too steep, you're losing a lot of fuel space, about 4" high on the outside edges is good. Your hot plate temps are quite low, maybe because of the much bigger gap underneath. If it stays that low you'll be fine with that top setup, but at 450/500c I've seen them break mortar and lift blocks up in the air. What chimney is it running on? |
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Post by treebased on Dec 22, 2021 16:20:21 GMT -8
What a beast Soot is not enough air, but that can be because the gas flow is too slow due to damp mass. Are you lighting the fuel from on top, primary air full open? Your chimney temps are too low, you want 140f minimum. Are you lighting small fires to dry it out? At those temps you will get condensate forming inside and leaking out the bottom. What's the ISA? Your V-floor is too steep, you're losing a lot of fuel space, about 4" high on the outside edges is good. Your hot plate temps are quite low, maybe because of the much bigger gap underneath. If it stays that low you'll be fine with that top setup, but at 450/500c I've seen them break mortar and lift blocks up in the air. What chimney is it running on? Lighting from the top, primary air (adjustable to 115% chimney csa max) wide open
I have been making my fires small to not crack the masonry until it can set. ISA 54ft2 not including the surface area of the engine (which I have yet to insulate, waiting on materials)
I agree my v floor needs to be rebuilt. I really like it removable for the ashes by the way, not sure how the metal will hold up over time but I have access to a lot of metal
I need a meter upgrade. I had a laser temp gun from my gas rc truck days but can't find it
6" single wall stove pipe, comes out of the floor of the bell at a 90, goes vertical through 2 x 45s, exits the roof into insulated double wall stainless with a rainproof cap.
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Post by Vortex on Dec 23, 2021 2:15:22 GMT -8
Small fires in a large firebox never burn as clean. Do you have a bypass, I cant see one in the pictures?
That's 5M2 ISA, which with your chimney exit so much lower than the firebox and the 90 bend, two 45's, mostly un-insulated chimney, you're pushing it a bit.
If when you get up to full loads you're still getting soot, then it'll be because the gas flow is too slow (because of the above), so even though you've got 115% CSA primary full open the draw will be too slow to get enough air into the fire. You have option there to improve that though.
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Post by treebased on Dec 23, 2021 9:57:42 GMT -8
Reconfigured the top box with a taller afterburner section (4.5" tall x9" wide x18.5" deep up from 3.5"tall) and it ran much better. I only eased the bottom corners this time with the same refractory paste stuff that seems to be working quite well. The top chamber is still oversized I think, 4.5"x12.5", so I put a fire brick on face in it to act as a test stumbling block. End port is 100% chimney csa. Moisture still appears to be working itself out of the system but the chimney is getting up to 145-150F at peak, top plate at 320F with only a slight bulge. The doors need to be sealed better, getting a whiff of smoke from the firebox door before the draw really gets started. Glass still soots up some but quickly clears after the draw gets going
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Post by treebased on Dec 24, 2021 13:16:32 GMT -8
Forming up to pour the last bit of the top of the bell at an angle which matches the roof beams, possibly the fall for a drainback water heating scheme to supplement a 240 gallon solar water heating battery tank in the darker parts of winter.
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Post by treebased on Dec 24, 2021 13:57:47 GMT -8
I was happy to see no cracking or failure of any kind on the inside of the bell, the refractory mortar seems to be holding up
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