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> snipped stuff re air trapped inside upper half of manifold in lauter tun
> >>Would it be problematic to drill one small hole on the top of the end of
> >>the manifold to let that air escape?
> > It probably would be fine to do....
> > Or would it be better to hold the
> >>manifold down with some sort of weight
> > Sure...grain....
> Seems like the grist, once stirred into the mashing water, would be
> suspended in the water and actually make the partially air-filled
> manifold even _more_ buoyant. The original poster complained of grist
> getting underneath the manifold. Is this a common problem experienced
> by others, or an apparently rare problem?
I do not have that problem and did not have it in the manifold I made of
CPVC...
And is it a problem of such
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> magnitude that it ought to be addressed in some way?
It would depend upon your setup...
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> snip
> > ... Where
> > a problem could occur would be on lauter tuns like my own where the
valve is
> > higher than the manifold. With the hole you would break the siphon that
is
> > created and may leave sugars in the tun near the end of the batch. If
the
> > total grainbed depth is say 8" and you use 1/2" CPVC then the total
height
> > of the manifold would be nearly 1". Assuming the outlet is 1" up of so,
> > with the hole at the top then you could potentially leave behind 1/8 of
the
> > liquid because of the siphon break. If you stop the fly sparge at 1.010
it
> > should not be problematic, but if you batch sparge you are certainly
leaving
> > sugars behind...
> Understood, and that would also depend upon your particular design;
> however, I'm not following your math. If the slots are cut half way
> through the pipe, thereby allowing air to enter to break the siphon at
> the highest point of the cut, as compared to the point where a hole on
> the top of the pipe allows air to enter (the height of the hole minus
> the pipe thickness, since air must get into the pipe), you would be
> talking about a difference of something less than a quarter of an inch
> of depth.
In terms of slots probably more like 1/2", but I was thinking for some
reason you meant the bottom would be drilled. Anyway that is how I have
made the last few coils and manifolds is drilled rather than slotted.
Mainly to keep from leaving sugars in the tun. Remember the diameter is ID,
not OD. The OD of 1/2" PVC is 0.84" at this manufacturer...
http://www.harvel.com/pipepvc-sch40-80-dim.asp
Spread out over a second and maybe a third batch sparge, I
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> can't see how you would even a 1% difference in extraction efficiency.
Dunno, you would have to try it to see...
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> And incidentally, if you're relying on suction/siphoning to drain the
> very bottom of your lauter tun (due to your drain being about the
> bottom), then I suppose braided SS would be bad because the siphon would
> stop as soon as the top of the braid is exposed.
I believe that would be true...
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> Now, about the situation where the drain from the lauter tun is higher
> than the bottom; assuming that the lauter tun is NOT completely filled
> all the way to the top edge, then why not tilt the whole thing a bit
> toward the drain, by inserting a shunt under the bottom at the opposite
> end. If this is done prior to vorlauf, would it hurt/affect anything?
I have done just that, and it probably would not hurt anything except I
finally realized I do not have slots that low and close to the spigot and
was not gaining anything by doing it that way in my case.
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> Fortunately for me, the ice chest I'm converting has a depression right
> near the drain so that the lowest part of the drain is almost flush with
> the bottom. However, when I checked the capacity of my ice chest, I had
> _NOT_ noticed how much of the lid protrudes below the top of the walls,
> which will reduce my volume. But maybe it won't be a problem since I'd
> probably want to leave some room to gently stir with a paddle anyway.
The CPVC manifold I made for a friend had a similar depression at the
outlet, my current mash coolers are higher...
Cheers,
Mike