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JackH
01/04/2019 10:55 AM
2 years today...Miss you Ginny!

JETROASTER
01/04/2019 4:24 AM
A little shout for the G'ster. 2 yrs. roar

allenb
12/27/2018 5:14 AM
Hi Brandon, please disregard the "please update". I think we're all up to speed now. The need for cache clearing get's me every time! limb

NetriX
12/26/2018 11:36 AM
Update? pouring Merry Christmas back atcha

allenb
12/26/2018 3:07 AM
Merry Christmas Brandon. Please update soon! christmas tree

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Heating Element Enclosure Ideas
CharcoalRoaster
What does everyone use for heating element enclosures? On my current roaster its just mild steel piping lined with ceramic insulation. On my new build I'd like to explore some alternative methods of enclosing my element?

Who's got some ideas to share?!~beach

Here's the element I will be using on my new build: https://www.ebay....2749.l2649
 
a1970gto
I've got mine in a ceramic tube, heating element is on a ceramic post inside the tube. That is all inside a 2" exhaust pipe. Once I get it more permanently set up it will be wrapped in some high heat insulation.

https://www.amazo...&psc=1
 
greencardigan
I use the elements from hot air guns. They generally come with the element inside a mica lined steel tube. I don't add any additional tube or insulation.
 
renatoa
What roaster design are we talking here ?
 
CharcoalRoaster
renatoa wrote:

What roaster design are we talking here ?


Fluidbed - I currently have a 500g capacity FB but would like to increase load capacity for this new build.
 
renatoa
In this case, the ebay element is too spread, imo
I.e. the volume of the enclosure hosting such element is too big, you will lose pressure.
 
allenb
Please explain why you suppose there would be a pressure loss?
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
renatoa
Maybe pressure loss wasn't the best term to use... the electric dryers are designed to work under no pressure, or very low, they are rather natural convection heaters, some even with no blower at all.
All the heat blowers I know, like hotguns, or Gene blower, are using very small volume heaters, the wire is condensed in the smallest possible space, as a hedgehog, to minimise the air area.
 
allenb
Most high temperature convection electric heaters are designed to minimize the amount of air bypassing or going around the resistance wire to keep the wire temperature as low as possible. Clothes dryer elements are necessarily designed around high flow, low static pressure blowers requiring heating elements within larger diameter housings. Since discharge temperatures are relatively low, even though there is a lot of bypassing around the resistance wire, wire temperature never goes beyond acceptable limits. On the other hand, using one of these to raise convection air streams up to 500F will require the wire to hit higher temperatures possibly into the yellow range which will reduce heater life. Sivetz designed some of their fluidbed roasters utilizing resistive heaters with quite a bit of bypass around the elements even more so than a clothes dryer design so it is possible to utilize them in this manner but life expectancy will be reduced by a margin. Seeing that the cost of these elements is very low, I would not hesitate to use them for a coffee roaster and you will probably get a few years out of it depending on usage.
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
renatoa
Still... for fluid bed we need air with high pressure passing through a straight pipe... in order to make the fountain. Not seen so far fluid bed made in flat pans...
So you say that air pumped in such large enclosure, exhausted by 1 inch pipe into RC, will not require higher power at input versus using a hot gun style heater ?
Air is compressible, not as liquids, where pumping 15 bars into an espresso boiler result into 15 bar at group shower...
 
allenb
Heating element enclosures can be any size/shape one desires as long as the enclosure doesn't leak and as long as one is careful to minimize heat losses through the enclosure walls to the exterior environment. At 10 to 50" H2O, compression of the air within the enclosure is not measurable and not a factor.

Edit: By "measurable" meaning one will see ill effects in the operation of the roaster.

Edit: "Any size" within reason. Obviously building one that is huge could create problems but utilizing a tube normally found in domestic clothes dryers will not be a problem.
Edited by allenb on 01/13/2019 11:09 AM
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
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