The Worst Thing about HX Machines/Heat Exchangers are evil - Page 2

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shadowfax

#11: Post by shadowfax »

HB wrote:I thought about automating the flush using the SSR on a cheap PID, i.e., one "flush" toggle switch that would open the group solenoid and run the pump until the grouphead temperature reached X, a second switch to start brewing. It's more a curiosity than anything, the extra seconds required for the flush aren't that onerous to me.
I agree. Flushing doesn't bother me at all. I know to do it, and I tend to view it as more of an opportunity to add a level of control to my shots than a confusing variable. I don't think I would bother to try to make my own "automated" flush control, but it would be a nice feature at a significantly lower cost than a PIDed double boiler.
Nicholas Lundgaard

LeoZ
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#12: Post by LeoZ »

this post hits on my 2 biggest flaws of an HX.
water use, and heat.

ok, so if you flush, and flush, and flush, you can pull a cool shot.
you can also use the 8oz of water to clean your sink. that scalding water will remove any gunk :D

it bothers me b/c its a lot of water, comparatively speaking. 8oz flush for a 1oz shot. shoot, i even turn off the faucet when i brush my teefs.
ok, the water is one thing, but wear and tear is another. your essentially creating 8x the wear on the pump and components as well from this.

next, is heat. this may be my machine more than hx's in general. but, leaving it on produces some serious heat. to the point where flushing still wont allow me to pull a cool shot. yes, sometimes i like 190F shots. first thing in the morning, piece of cake. 12 hours later, not a chance. :)

so, is a double boiler rotary pump machine the answer? probably not, huh?

djmonkeyhater

#13: Post by djmonkeyhater »

It is hard for me to imagine an HX is what you would come up with from a blank sheet of paper as a way to supply two different temperatures of water, in two different quantities to two different places with precision, serviceability, reliability and/or flexibility. Less so in a commercial setting with varied users and production volumes.

I set my Astoria Lady boiler at 194 degrees for a couple days while I was setting it up and thought "This is how one would make straight espresso in quantity."

HX's are compact, seemingly easy to execute, reasonably simple and widely-used but I don't think they are the most predictable way to get good espresso in a cup in 2008.

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jmcphail

#14: Post by jmcphail »

Nicely put, i've been trying to think of a reasonable, non-confrontational way to say exactly that.
djmonkeyhater wrote:HX's are compact, seemingly easy to execute, reasonably simple and widely-used but I don't think they are the most predictable way to get good espresso in a cup in 2008.

ira
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#15: Post by ira »

Having purchased a Brewtus II and a Macap M4 electronic doserless grinder for my foray back into the world of espresso I'm extremely happy that I choose a dual boiler machine as I don't want to think as much as it seems people have to when dealing with HX or single boiler machines. The machine and grinder arrived with 6 lbs of mystery coffee that I tried using, how was I supposed to know it was pointless? Now that I can make a cappuccino that served to guests seems to always make them want more I have to try and teach my wife to use the machine and that makes me really glad for the dual boiler as I can't imagine teaching her how to use an HX machine. Heck, she fails boiling water on occasion and the whole concept of flushing is likely far beyond her ability to care. The fact she doesn't drink coffee likely makes it even harder.

Ira

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cannonfodder
Team HB

#16: Post by cannonfodder »

A thermosiphon flow restrictor does wonders for managing group head temperature and it substantially reduces the flush amount. I cut my teeth on heat exchanger machines and short of my lever machine, all my machines (including a two group) are heat exchanger. Having said that, if I was opening a café, I would not give a HX machine a second look, I would go straight to the double boiler. Since I would be using one blend and it would remove one of the big factors in making a shot. I would have to assume that the person making the drinks was less fanatical about the shot than I. But I can get equally good shots from either type of machine, one just takes a little more knowledge and one extra step to use and is quite a bit less expensive than the other, which is another major factor in an upstart business.
Dave Stephens

LeoZ
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#17: Post by LeoZ » replying to cannonfodder »

how different a drink will a double boiler produce? why would using more than one blend matter for a double boiler?
thanks..

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cannonfodder
Team HB

#18: Post by cannonfodder »

Different blends will pull at different temperatures. A heat exchanger lets you adjust the temperature by the length of cooling flush/rebound. A double boiler would need a PID temperature change and another hour or two to heat/cool to the new temperature. The 4 group LM use two different brew boilers, so if you had one, you could set group 1&2 at one temperature and groups 3&4 at another to solve the one blend or two problem.

Cup taste is effected by more than just the boiler type, internal makeup, piping, dispersion blocks, etc... make a difference. otherwise every machine out there would pull an identical shot.
Dave Stephens

LeoZ
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#19: Post by LeoZ » replying to cannonfodder »

agreed on the cup taste, makes sense. can you expand on that? im debating DB setup just b/c im tired of flushing. wondering what to expect in the cup..

re: non pid double boilers - cant the pressure be adjusted to get you in the ballpark? granted, having varying blends throughout the day make this difficult.

i was under the impression common DB machines (brewtus, la spaz) have PIDs, or at least an easier on the fly change.

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shadowfax

#20: Post by shadowfax »

LeoZ wrote:i was under the impression common DB machines (brewtus, la spaz) have PIDs, or at least an easier on the fly change.
On the fly change is one thing, but to get really accurate brew temps the machine has to stabilize, from the boiler to the extremities, the grouphead, portafilter, etc. a PID can't really make that happen faster. Stabilization will take some time. I dunno about hours, but awhile. I'd defer to Dave on that, I believe he's actually probed them... right?
Nicholas Lundgaard