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Post by tallgrass on Apr 4, 2016 18:32:54 GMT -8
Hi all! I built an 8" batch box following all the dimensions as close as i could, batchbox itself was right within a 1/4" in depth, width and height and the port to the riser was spot on as well. The p-channel i installed hung down only an 1 1/2" below the top of the port and the only other dimension that had variation was with my octagonal riser. It is not an insulated riser unfortunately, i had a pallet of reclaimed dense clayburn firebrick at my disposal and built the riser square and inserted the small triangular firebricks i'd seen done before to create a riser with the csa of the 8" exhaust. Only problem was cutting 60 triangular pieces with my brick saw i had very minute variations in their size. It vents a foot and a half below the capped bell and then runs through a hollow bench with exhaust at the end. It fires up wonderfully! Within 60 seconds it was smoke free, even from a cold and wet first start. Bell size has an ISA of 90 sq. ft. The fire burns properly until i stick the door in place (gasketed by kao wool). With a full load and door on, the firebox begins pantint quickly and little bursts of air come out of the primary intake as opposed to a continuous sucking motion. After about 5 or 10 minutes as the entire batch ignites, through the primary returns to normal. Any idea why this is happening to me? m.youtube.com/watch?v=9fK8WvLfp7g
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Post by satamax on Apr 4, 2016 23:08:18 GMT -8
Pulsating, you have a restriction somewhere. Have you tried to run it again, with the door open?
Wood blocking the port?
Restriction between heat riser and bell? As you said,
Not enough primary air?
I imagine, with a door well sealed, it could gaseify in the firebox, faster than it burns. Just to check for this, open slightly the door.
On mine, it does pulsate from time to time. At startup, I just do this, leave a 1/4 inch gap at the door, and you see it dancing with the pulses. Nothing like yours tho. But my door is npwhere near tight, and I have no hole for primary air, just a gap around the door.
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Post by peterberg on Apr 5, 2016 1:08:45 GMT -8
I think Max is right, restriction somewhere. Not fatal but annoying and when the chimney temperature is ramping up the pulse disappears. It's a bell system and the top gap is spaciously, that's good. The transition from the main bell to the bench could be the culprit but also the exhaust opening to the chimney. Keep in mind, when those openings are at floor level the bottom portion of the opening isn't used by the gas stream because all the gases are entering from above. Moreover, the stream need to go around a 90 degree bend at those spots so here the 150% rule comes into play. That is, stream profile should be 150% of system size. So, what are those openings like, how are they situated and what is their size?
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Post by tallgrass on Apr 5, 2016 7:19:24 GMT -8
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mudder
Junior Member
Posts: 50
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Post by mudder on Apr 6, 2016 5:33:05 GMT -8
great looking stove sir!
if taking the door open stops the problem cut the hole bigger. you can always fab a damper on the steel door. if you dont want to cut it prop it up a half inch or so, at a time.
again great work! love it
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Post by cobprojectcampus on Apr 11, 2016 10:55:27 GMT -8
Jim is a great guy and teacher he was our first official instructor for this style of heater. We look forward to keeping in touch for how the stove performs and any updates on cob-ing around the bench parts. Jim is welcome here at CPC anytime!
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