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Post by chrisz on Jan 15, 2014 7:46:54 GMT -8
I'm wondering what you all think about the possibility of taking a 4" rocket j tube, and hooking it up to a radiant tube heater pipe similar to this . . . www.reverberray.com/?product=ld-series. The j tube would be insulated to achieve a clean and complete burn, then instead of it going into a barrel or a bell run it straight up to the ceiling and attach it to a radiant tube pipe that runs the length of the garage, possibly loops back before it goes up and out the roof. Has someone done this? Has someone thought about this? Is it a workable idea? Would i need to keep the radiant tube pitched to maintain proper draft, or if there is a 10' rise at the end it'll be fine? thank you cz |
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Post by pinhead on Jan 15, 2014 10:04:39 GMT -8
I haven't done it but after experimenting with the radiant barrier behind the barrel in my stove, I'm very interested in the idea.
The draft of the J-tube would be sufficient to keep the air moving. Depending on your exit temperatures, a chimney may or may not be needed. Since there would be no "down draft" portion - no barrel to bring the gasses back down to floor level - the draft of the J-tube would be sufficient.
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Post by Dan (Upstate NY, USA) on Jan 20, 2014 4:20:23 GMT -8
I have though about it and I think it could work. Remember when you cool the gases fast enough you are creating a relative vacuum to the pressure that the feed air is coming in...
Thats why the barrel works so well when NOT insulated with cob, it cools he gases to the point of creating an area of low pressure...
I just don't know if it could be done with 4" system, maybe a 8" going eventually to a 6" or maybe a 6" going to a 4"...
Looking forward to what you find out...
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Post by pinhead on Jan 20, 2014 8:28:01 GMT -8
If your system doesn't have any down-draft tubes than you most definitely won't have to worry about draft -- assuming your exit/flue temperature is higher than the outside temperature. I have though about it and I think it could work. Remember when you cool the gases fast enough you are creating a relative vacuum to the pressure that the feed air is coming in... Thats why the barrel works so well when NOT insulated with cob, it cools he gases to the point of creating an area of low pressure... I just don't know if it could be done with 4" system, maybe a 8" going eventually to a 6" or maybe a 6" going to a 4"... Looking forward to what you find out... As the temperature of the exhaust gasses drop, it doesn't create a vacuum; it will simply condense and its volume/velocity will be reduced. The "mass-flow" will be the same at the entrance as the outlet but velocity will be different due to the change in volume. The "vacuum" is only created at the vertical transitions into lower temperatures. In other words, the exit of the heat riser to the barrel where the temperature is relatively low (relative to the exit of the heat riser), and the exit of the vertical chimney to the outside air. Any condensing of the gasses along the way reduces draft not due to "vacuum" created by condensation; draft is reduced only due to the temperature differential at the exit being reduced. Non-forced-draft stoves are simply driven by convection. |
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Post by Dan (Upstate NY, USA) on Jan 20, 2014 18:52:13 GMT -8
Relative to the pressure at the top of the heat riser. I don't know about other peoples stoves but if I put some incense around the cracks at the base of my steel barrel it DRAWS in the smoke. This is a vacuum in the terms of less than standard atmospheric pressure 14.7psia. I am sure my 27' of triple wall pipe that starts 30' away allows for this vacuum created by cooling gases in the steel drum to continue.
I think the driving force of the J-tube is the vacuum made by the cooling gases in the drum, much in the same way cool lake or ocean water cooling the gases in the tubes of a steam turbine exhaust stream creates a vacuum (a much greater vacuum since it is all steam) that allows the turbine to do more work...
Thats why I think barrels that are cobbed under perform barrels that are not insulated...
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