Why PID an HX Machine? - Page 2

Need help with equipment usage or want to share your latest discovery?
PaulTheRoaster

#11: Post by PaulTheRoaster »

They're also silent and last forever.

User avatar
Compass Coffee
Sponsor

#12: Post by Compass Coffee » replying to PaulTheRoaster »

True PID silent but in application usage may or may not be the case. Depends whether using SSR or mechanical relay. :wink: Nothing lasts forever, computers fail all the time.
Mike McGinness, Head Bean (Owner/Roast Master)
http://www.CompassCoffeeRoasting.com

Baratza: skilled in the art of grinding
Sponsored by Baratza
PaulTheRoaster

#13: Post by PaulTheRoaster »

Compass Coffee wrote:True PID silent but in application usage may or may not be the case. Depends whether using SSR or mechanical relay. :wink: Nothing lasts forever, computers fail all the time.
Yeah, yeah. Also be sure to put some heat-sink compound on the heat-sink on the SSR and mount it such that the heat-sink can do its job.

User avatar
cafeIKE

#14: Post by cafeIKE »

What Greg said.

What Ken said, except that with planning the aggravation is less than it takes to descale. With all the bits in hand, actual PID installation and boiler insulation took less than two hours. HX and boiler descale is a half day process and much more of a PITA.

If you choose your HX machine wisely, you can have your latte and espresso too.

I'm not obsessively fastidious about ±0.1° temperature variation or perfect foam every time. What I desire is damned fine espresso without a lot of hoopla. The missus desires her latte sans CLACK. The Vibiemme HX with PID delivers on all accounts. I can walk up any time, pull a shot for her latte, steam milk and pull my double with no flushing at all.

For a dinner party, two button presses put me back in full HX mode for frufru production with out the need to partially disassemble the machine, adjust the pStat, wait until the machine stablilizes, adjust the pStat, wait until the machine stabilizes, etc. AND no guest asks, "What's that CLACK?"

Just the lack o' CLACK is reason enough to PID an HX, regardless of the setpoint.

Ken Fox

#15: Post by Ken Fox »

PaulTheRoaster wrote:Yeah, yeah. Also be sure to put some heat-sink compound on the heat-sink on the SSR and mount it such that the heat-sink can do its job.
The SSR could certainly fail at some point, but they are readily available and cheap; just check ebay.

If the controller is mounted inside the machine and exposed to heat, all bets would be off as to its longevity, although I know at least one person with such a setup who has had no problems with it.

The SSR does not necessarily need to be mounted onto a "heatsink," per say, if what one means is a thingie called a "heatsink." In some cases, the case material of the espresso machine can serve as the heatsink. This is exactly how I mounted the SSRs in both my machines; facing downward on the bottom casing of my Cimbali Juniors, screwed in and with heatsink compound on the interface. I sanded off the paint on the bottom case, to expose bare metal, at the point of attachment.

I arrived at this solution after considering whether or not I had room for a formal "heatsink" in this location were I to mount the SSR there. So, I called the MFR. of the SSR and spoke with a very knowledgeable tech support person who steered me to online materials showing the needed heat dissipation of the SSR I was using. He felt my machine almost certainly had enough metal on the mounting surface to dissipate the heat, but he suggested that in order to be certain, that I put a thermocouple under the contact point to measure the SSR in actual use, to insure that the bottom of the SSR was not getting too hot, e.g. that it was evacuating its heat appropriately through the case. I did this and found temperatures considerably below what was considered acceptable for this SSR, during periods of maximum SSR usage, such as during the boiler heatup phase and after evacuating water and steam out of the boiler and then refilling it rapidly, calling for nearly constant "on" boiler element conditions.

Of course, a Cimbali Junior is a fairly massive machine and other machines' cases may not have the same heatsinking capability; one would have to test it.

Finally, it goes without saying that the terminals on a SSR are electrically "live." Anyone contemplating an installation such as I have done will need to purchase a plastic SSR top cover, to protect the SSR terminals from water splashing should there be any problems with the machine which could make this a potentially dangerous PID installation. Also, I'd suggest that using a GFCI outlet is more or less mandatory.

ken
What, me worry?

Alfred E. Neuman, 1955

OkcEspresso

#16: Post by OkcEspresso »

I have a PID on my CMA (Laurentis) single group machine with a 5 liter boiler. Combine that with a PID (for monitoring purposes only) attached to a thermocouple that is mounted inside the group (just above the giculeur) and I have an espresso making platform that is ugly as hell but is verifiably predictable and calibratable. With the thermo in the group, I could probably surf the temp the same way I do with the PID. However, as has already been declared in this thread, adjusting the boiler temp with the PID is a couple of button presses, with the pressurestat it is several screws and cooling the machine down.

User avatar
cafeIKE

#17: Post by cafeIKE »

Ken Fox wrote:Of course, a Cimbali Junior is a fairly massive machine and other machines' cases may not have the same heatsinking capability; one would have to test it.
Stainless is a poor heat conductor relative to aluminum or carbon steel, so choose the SSR location carefully to ensure long life if the SSR mounting location is stainless.

In the initial installation of the Omron G3NA-220B SSR, it was mounted to the stainless steel bottom of the machine. This location was chosen because, in the event the stainless case provided insufficient dissipation, there was room to mount a heatsink on the outside.

During boiler heating, the metal in the SSR would exceed 40°C, the derating corner temperature. Adding the mating Y92B-A100 aluminum heatsink on the outside bottom of the machine reduced the worst case temperature to below 33°C. At operating load, the metal is barely warm to the touch. Note : This location requires milling the heatsink upper surface to mate with the bottom of the machine.


Heatsink Location

Regardless of the location chosen, always make sure there are drip loops, i.e. low points below the terminal, in the wiring to ensure any stray moisture cannot run down the wire into the connection or SSR.


Omron GN3A-220B load graph from Omron technical document D20G3NA0305.pdf

Cerini Coffee & Gifts: official US importer for Olympia Express
Sponsored by Cerini Coffee & Gifts
User avatar
erics
Supporter ★

#18: Post by erics »

The Quickmill Anita (for sure) and probably(?) many other hx machines in its class are already equipped with a 25A SSR. The pstat switches the SSR and the SSR does the job of handling the heating element. Any machine that has a Sirai pstat probably uses it to switch the heating element directly.

I once suggested to someone that in lieu of installing a PID on his hx machine that he simply crank down the pstat to 0.6 Bar territory and see how he likes the results. Well, here are the results on Anita:



I wasn't necessarily shooting for 0.6 bar (but that's where it ended up) rather I was going for ~ 198 F group temperature. Steaming capability is still there at 0.6 bar but obviously not quite the same as 1.2 bar. Machine recovery, back to 198 F group temp, after pulling a "real" shot this AM, was a little longer than desirable - about 20-25 minutes. As others have said, the PID'ed hx does give you a lot of control when trying out different beans/bean blends and most definitely it will provide very repeatable results which I view as a most desirable attribute.
Skål,

Eric S.
http://users.rcn.com/erics/
E-mail: erics at rcn dot com

Ken Fox

#19: Post by Ken Fox »

cafeIKE wrote:Stainless is a poor heat conductor relative to aluminum or carbon steel, so choose the SSR location carefully to ensure long life if the SSR mounting location is stainless.
stainless is also relatively expensive, and although it is commonly used on outer machine panels, it may not be commonly used in the sort of location (bottom internal casing) as I was describing in my machine. I sincerely doubt that the panel I mounted my SSR on is made of stainless. It was painted black, something you would be unlikely to do with stainless but would do with something like plain steel or possibly aluminum. Also, it was easy to drill through. Stainless is a bitch to drill through, which would give me pause as the installation would likely end up being a PITA.

ken
What, me worry?

Alfred E. Neuman, 1955

LeoZ

#20: Post by LeoZ »

erics wrote:I wasn't necessarily shooting for 0.6 bar (but that's where it ended up) rather I was going for ~ 198 F group temperature. Steaming capability is still there at 0.6 bar but obviously not quite the same as 1.2 bar. Machine recovery, back to 198 F group temp, after pulling a "real" shot this AM, was a little longer than desirable - about 20-25 minutes. As others have said, the PID'ed hx does give you a lot of control when trying out different beans/bean blends and most definitely it will provide very repeatable results which I view as a most desirable attribute.
this sort of relates to my thread that youve been really helpful in. I havent had time to experiment further, but, at 0.7bar, some coffees are great, and some are terrible. HX inconsistency, well, rather, its tight deadband of temp/pressure, seems just too limited for my tastes. for now, ill try to work with it, but long term, like you said above, try a double boiler or so.



anywayyyyy..onto the meat of my post.

you chose your boiler pressure based on a group temp of 198. do you find that group temp ideal to pull shots without a flush, or, just a really short flush?

from what ive seen at 0.7bar, group temp is around 205(ish) and the water appears to start at a fairly low temp, around 155, then creep up to 198ish. im assuming it stabilizes around there, cant recall.

but, again, without a longish flush, youre still going to get temp instability. itll either drop at boiler pressures of 1.1 bar, or raise at 0.6 or 0.7 bar. your chart shows youre still flushing around 4-5oz in those 6 seconds or so until temp stability is maintained, or, are you actually pulling the shot from a cold start, and just letting the first amounts of coffee to be extracted cold?

that brings up another issue, if stability isnt maintained across the entire time of the shot, isnt final outcome affected?

so, start colder and increase, or start hotter and decrease. in the end, does it matter?

i think what im driving at, is that there must be an ideal pressure/temp crossover point where stability between grouphead temps and water temps are close enough that flushes are small and stability is maintained, and, of course, the results tastes good.
question is, what the hell is it! :)


lots of questions, huh?!