How Autofill Degrades Shot Temperature Stability - Page 4

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cannonfodder
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#31: Post by cannonfodder »

I make a practice of dumping a couple of cups of water out of the water tap every day or two (I have an 11 liter boiler) to keep the mineral buildup to a minimum. As the water vents out in steam, the mineral content of the boiler will increase and get steadily harder.

Do a hardness test on your tap water, then after a month or two of usage (no water purge just steam) dump some boiler water into a pitcher, let it cool and do a hardness test on it. There can be a dramatic jump between tap and boiler.

I occasionally make hot chocolate for the wife or kids and an occasional tea for myself. I like to keep the boiler water fresh, it can get a stale off taste if it gets old.
Dave Stephens

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Compass Coffee
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#32: Post by Compass Coffee »

cannonfodder wrote:So in real world situations, the autofill is little more than annoying provided you allow a few extra seconds for the boiler to recover. Any taste difference would be minor and probably not noticed by most people.
That's my take on it, as far as it pertains to me and my Bricoletta.
... the blown shots from the autofill engaging during an extraction is a bit more annoying. It would definitely have a negative impact.
Fortunately that one's not an issue with the Bric' 'cuz autofilling during a shot, especially at the start of the shot, would highly likely cause a sink shot.
I would imagine the size of the boiler would also play a part in how often the autofill kicks on as well as the impact it has. A smaller boiler would be impacted much more severely than a large boiler.
Of course with larger sized boiler it might be expected autofill would also be bringing in more cold water during autofill so recovery might be as much or likely more impacted taking longer to recover than a smaller boiler if the same heating element power. For example let's say one machine has a 3.5L boiler and the other 1.5L and both have 1500w heaters. Let's also say they both autofill when down to 50% filling to 75% full. It would take longer to heat the 0.875L cold water added to the 3.5L boiler than the 0.375L cold in the 1.5L. (Have no idea what typical boiler autofill deadband is, just made up an example) But then since the larger boiler would refill less often so maybe an overall wash recovery impact wise in production. But two boilers of equal size but different power heating elements the lower power would indeed highly likely be more severely impacted.
Mike McGinness

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cannonfodder
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#33: Post by cannonfodder »

All things being same, the guy with the most horsepower wins.
Dave Stephens

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RapidCoffee
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#34: Post by RapidCoffee »

cannonfodder wrote:Interesting. I thought that the rotary pump machines had sufficient flow capacity to make it through a mid shot fill. My understanding was that there would be a drop but not as drastic. Learn something new every day.
Yeah I know - but this makes sense, at least in hindsight. The pump setting doesn't change, but during autofill the flow is directed to the boiler as well as the group head. Stands to reason that the group head flow will be reduced, unless the pump somehow "knows" it must push twice as much water. Apparently my pump's not that smart.
________
John

Ken Fox (original poster)
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#35: Post by Ken Fox (original poster) »

Compass Coffee wrote: So I asked myself if I'm entertaining and making a bunch of back to back caps (snipped)

Worthless post as far as hard data goes maybe, but as far as real world usage goes possibly beneficial.
In my opinion, and this is just my opinion, fine temperature control is more or less irrelevant in milk drinks, so if you are making cappa after cappa after cappa, what the recipients of these drinks are going to notice is how good was your milk frothing, not what temperature the shot of espresso was made at.

I think that temperature management would only be important if you were making some milk drinks and some straight shots; fluctuations in temperature, if large enough, would be noticed in the straight shots that were part of the series.

At this point in my understanding of this phenomenon on my machine with autofill, I know only that it happens. I don't know whether it is due to autofill occuring during shots or simply between them; what I do know is that bypassing autofill reduces variation in inter shot temperatures. It could be that shutting off or modifying when autofill comes on will effect shot temperatures obtained for shots that go into milk drinks also but I think the real impact would be in the straight shots that are part of the series.

ken
What, me worry?

Alfred E. Neuman, 1955

Ken Fox (original poster)
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#36: Post by Ken Fox (original poster) »

HB wrote:It works for me. However, putting a momentary switch to disconnect the water level sensor would allow you to overfill the boiler slightly, assuring that no autofills would occur in the next session. Such a switch would also come in handy when descaling (i.e., when overfilling the boiler with descaler to cover the scale line). Essentially the combination of a manual and autofill.

(How long will we have to wait for Ken "Mr. Thermofilter / Omega Datalogger" Fox to post graphs demonstrating the effects of different boiler levels introduced by this suggestion? ;-))
Of course you wouldn't know how far you were overfilled in a boiler without a sight glass and your slight overfills each day could easily end up with a fully topped up boiler over time. Having had an overfilled boiler for a while after my input solenoid failed, I can tell you that the machine functions poorly in that state.

I have informally tested varying water levels in my vibe machine with a sight glass and at least on my system with its large heat exchanger I did not find big shot temperature stability differences. Nowadays I just fill the boiler up in between the "min" and "max" levels on the sightglass and try to leave it more or less in that position, which works well for frothing as well.

I actually much prefer the Fluke 54-II datalogger, but since I don't have the software for downloading its data, I use the much les fun to use Omega for those tasks.

ken
What, me worry?

Alfred E. Neuman, 1955

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Compass Coffee
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#37: Post by Compass Coffee »

Ken Fox wrote:In my opinion, and this is just my opinion, fine temperature control is more or less irrelevant in milk drinks, so if you are making cappa after cappa after cappa, what the recipients of these drinks are going to notice is how good was your milk frothing, not what temperature the shot of espresso was made at.

I think that temperature management would only be important if you were making some milk drinks and some straight shots; fluctuations in temperature, if large enough, would be noticed in the straight shots that were part of the series.

At this point in my understanding of this phenomenon on my machine with autofill, I know only that it happens. I don't know whether it is due to autofill occuring during shots or simply between them; what I do know is that bypassing autofill reduces variation in inter shot temperatures. It could be that shutting off or modifying when autofill comes on will effect shot temperatures obtained for shots that go into milk drinks also but I think the real impact would be in the straight shots that are part of the series.

ken
I don't disagree. I ran test series of caps' test only because it would force autofill faster than shots only or mixed shots and caps'. In real life entertaining scenarios I'm more often pulling straight shots or mostly straight shots versus all caps.
Mike McGinness