SCACE + Eric's Thermometer and still confused.

Need help with equipment usage or want to share your latest discovery?
F1

Postby F1 » Jul 12, 2018, 2:12 am

I have had this never ending problem with early blonding + bad flavor with every coffee for YEARS. I have tried everything at this point. Super Jolly, Compak K10, K30 Vario, WDT, no WDT, Pullman Chisel. My Profitec Pro 700 absolutely sucks and for some reason my Rocket Giotto works.

I have ran out of settings to try on the PID with the Pro 700. I have installed Eric's thermometer a while back. I also have a SCACE which should eliminate the need to even consider using Eric's thermometer, but I am actually a lot more confused if I use both at the same time.

When running the SCACE at the 20sec mark the SCACE shows 200F and Eric's shows between 206F to 207F and stays there pretty much flat for the duration of the shot. That's fine I know Eric's is supposed to show several degrees higher than actual puck temperature. As the shot progresses the SCACE very slowly climbs 200.1, 200.2, 200.3 and so on until the end of the simulated shot. By the end of the shot the SCACE shows a max of maybe 201F. This is all normal behavior so I am not worried about that.

The issue is when I run a portafilter with coffee. Obviously I can't use the SCACE so I look at Eric's thermometer. You would think it should behave the same, but it doesn't. As soon as I start the shot Eric's thermometer the first few seconds are the same as with the SCACE. Eric's thermometer climbs to 207F and stays there for maybe 2 seconds, then it starts dropping rapidly and by the 20 sec mark it is at 202F and at 25sec it is at 197F. This means that in the puck the temperature is around 200F for the first few seconds and by the end of the extraction it is around 190F. This would explain why every single coffee I make with the Pro 700 blonds so fast and tastes underextracted, but when made with the Rocket Giotto they dont.

There are no leaks on the machine and all the internal seals have been changed even though it shows no temperature drop with the SCACE. Most of the coffees I make at home I have tried at coffee shops so I know how they are supposed to taste. With the Giotto I can replicate these coffees at home, but not with the Pro 700. I don't get it. Any help?

F1

Postby F1 » Jul 12, 2018, 2:57 am

I also need to add that I have an idea as to why it behaves different with coffee. I think it has to do with the initial resistance of the dry coffee puck. With the SCACE there is flow immediately as soon as the extraction begins. With a portafilter with coffee it takes several seconds before the water travels through the bed of coffee and comes out the bottom of the portafilter. During those seconds there is a mix of water being cooled down by the coffee bed and new hot water pushing behind. This I think causes Eric's thermometer to show a drop in temperature a few seconds into the extraction. If I run a really coarse grind(gusher) that's the only time Eric's thermometer behaves the same as when also running the SCACE. With a gusher there is flow at the bottom of the portafilter almost immediately so there is less mix of hot water and cool water.

With the Giotto I see this behavior as well, but the temperature only drops about 2 degrees before it quickly recovers to 207F on Eric's thermometer. With the Pro 700 it is just a continual drop in temperature through the extraction.

DaveC

Postby DaveC » Jul 12, 2018, 8:18 am

Perhaps I can add something to this. almost 15 years ago I invented something I still use to this day to measure temperature in espresso machines. I suppose it's similar to a SCACE II, but I believe has some differences. I have embedded my sensor about 3-4mm into a simulated coffee puck. I ensured the simulated coffee puck has the same headspace as a normally filled portafilter, offers an almost identical resistance and wets throughout.

I did it like this specifically because of the way water flows through the group, fast initially filling the headspace then building resistance as it passes through the coffee bed. I can't simulate it exactly, because of the way my device has to be used. The embedded probe and the fact that it is always damp after the first use and it has to be damp to have the flow even throughout (because it's not coffee). It can however indicate 2 things when used 2 different ways.

1. The way the temperature in the coffee rises, because it's essentially cold when the water hits it
2. What the temperature of the water hitting the coffee is

The above are 2 totally different values of course and when tuning a machine I have to use the second value. In almost every case of a well set up (or even not well set up machine) machine, the temperature in the coffee doesn't change after flow begins...even though that flow may be much restricted from the initial part of the shot. The larger the offset, the more likely one is to see differences especially where erics thermometer measures...but less so in the coffee puck.

If you want the temperature to be better maintained in the group, you can try increasing the offset a tad...this will make the water hitting the coffee a tiny bit hotter but the coffee won't mind too much because as it comes up to temperature, flow rate will slow and the group will bring the temperature down slightly. What you will have though is overall a slightly warmer group and portafilter overall. This is going to help stability within the coffee during the shot. You will still probably see erics thermometer dip, but I don't believe it's an accurate reflection of what's happening in the coffee at that point.

JayBeck

Postby JayBeck » Jul 12, 2018, 9:00 am

I'm sure you've tested this too, but:

When pulling a normal shot, are you using a bottomless portafilter? If so, how is the beading phase and how long does it take from pump on for the flow to begin? If your flow is too fast, then you're going to pull water much quicker than with a SCACE which has a constant flow. The faster the flow the faster the temperature drops.

Are you using the same portafilter holder and basket as your Giotto? What about the same shower screen and gasket? I recently had an issue with major channeling that ended up being caused by a deformed gasket that was 8mm on 3/4ths and around 7.5mm on the other 1/4th of the ring. I would make sure you are removing as many variables as possible.

Lastly: Is your Giotto one with a vibration or rotary pump? The Giotto has more Pre-Infusion than the Pro 700 by design. If you have the vibration pump version, pre-infusion is even longer than on the rotary pump version since vibe pumps ramp up to pressure over the course of 4-5 seconds whereas a rotary pump is at 9 bar nearly instantly. My guess is you need to grind finer on your Pro 700 than your Giotto in order to restrict the flow more. This is most likely your culprit.

danny31292

Postby danny31292 » Jul 12, 2018, 9:23 am

I, like you, put my thermometer on my DB machine when I upgraded from a HX. Pretty sure my thermometer hovers around 207 for the entire shot. I'll check next time I pull a shot. Hopefully others will chime in with their idle temp and shot temps too. Mine idles around 196 with the PID set at 200.

Jenda

Postby Jenda » Jul 12, 2018, 11:27 am

Hi F1,

I responded in the past to one of your many issues and I will try to describe my procedure again:

I am an European owner of a Profitec Pro 700 and Eric thermometer. I use all the default PID settings, offset (E1) defaults to 27F (15C) even with the new upgraded PID. Except of my T1 setting which is 94C (~201F), default is 93C.

With the steam boiler off, locked portafilter and idle time >1 hour, outside temperature ~25C, the Eric shows idle temperature 196-196.5 and with the steam boiler on 196.5-197F.

17-18g in 18g VST, no WDT, medium to light roasts.

I do only 1s flush or less. It may be crucial.

Pulling ~30s shot temperature rises up to 209F, drops down to ~203F, around 20s I get ~205F and the shot ends at 207F.

I had an issue with the too low idle temperature which was solved probably by replacing almost all the gaskets and seals and valves too in the group head.

If your machine behaves in the different manner I would suspect that gaskets, seals, valves, maybe gicleur. You should also check temperature probe in the coffee boiler if it is without any hissing and leaking.

gscace

Postby gscace » Today, 8:49 am

Hi there: Comments are embedded in your text.

F1 wrote:I have had this never ending problem with early blonding + bad flavor with every coffee for YEARS. I have tried everything at this point. Super Jolly, Compak K10, K30 Vario, WDT, no WDT, Pullman Chisel. My Profitec Pro 700 absolutely sucks and for some reason my Rocket Giotto works.

I have ran out of settings to try on the PID with the Pro 700. I have installed Eric's thermometer a while back. I also have a SCACE which should eliminate the need to even consider using Eric's thermometer, but I am actually a lot more confused if I use both at the same time.

When running the SCACE at the 20sec mark the SCACE shows 200F and Eric's shows between 206F to 207F and stays there pretty much flat for the duration of the shot. That's fine I know Eric's is supposed to show several degrees higher than actual puck temperature. As the shot progresses the SCACE very slowly climbs 200.1, 200.2, 200.3 and so on until the end of the simulated shot. By the end of the shot the SCACE shows a max of maybe 201F. This is all normal behavior so I am not worried about that.

The issue is when I run a portafilter with coffee. Obviously I can't use the SCACE so I look at Eric's thermometer. You would think it should behave the same, but it doesn't. As soon as I start the shot Eric's thermometer the first few seconds are the same as with the SCACE. Eric's thermometer climbs to 207F and stays there for maybe 2 seconds, then it starts dropping rapidly and by the 20 sec mark it is at 202F and at 25sec it is at 197F. This means that in the puck the temperature is around 200F for the first few seconds and by the end of the extraction it is around 190F. This would explain why every single coffee I make with the Pro 700 blonds so fast and tastes underextracted, but when made with the Rocket Giotto they dont.

Eric's device and mine don't measure the same thing. Eric's device is measuring water inside the group at the precise position of his thermometer, and mine measures water exiting the shower screen at the precise position of the thermometer. Eric's number is higher than mine because energy (heat) is lost between Eric's measuring point and mine. And Eric's measuring point is sensitive to thermosyphon action, which is somewhat complicated at times. It's pretty simple when the machine is idle. Less dense, relatively hotter water leaves the heat exchanger from the top, enters the group from the top, cools in the group, and becomes more dense. The denser water exits the group through the bottom pipe and flows back to the bottom of the hx. This convection cycle is the so-called thermosyphon action. Things change when brewing is activated. Thermosyphon stops and now water enters the group from both the bottom and top of the hx, with the proportion from top and bottom dependent on the respective flow resistances of the top and bottom flow paths. Scace devices employ a simplified flow scheme - a nozzle. So flow rate during brewing remains constant at approximately 55 gm/30 seconds at 9 bars of pressure. This value is nominally comensurate with 18 gms of coffee producing a brew ratio of 50%, assuming the dry coffee absorbs its weight in water (a pretty good assumption). But the constant flow rate idea is not what actually occurs in real brewing. Dry coffee has much less resistance to water flow than wet coffee. It aggressively absorbs water, is as full as possible of dissolvable solids, and it swells up as it absorbs water. Consequently the flow rate of water is very high in the first couple of seconds, and drops way down as soon as the coffee has absorbed all of the water that it can. What you see in Eric's device (the difference in behavior of Eric's device when measuring during real brewing vs. measuring against a Scace) is the thermal response to this big flow pulse at the beginning. In practice it doesn't matter by the time the water flows through the group as the temperature gets attenuated by the internal components of the group and energy loss to the surroundings.


There are no leaks on the machine and all the internal seals have been changed even though it shows no temperature drop with the SCACE. Most of the coffees I make at home I have tried at coffee shops so I know how they are supposed to taste. With the Giotto I can replicate this coffees at home, but not with the Pro 700. I don't get it. Any help?


Here are a couple of suggestions and ideas. Use VST baskets. Temperature and pressure are only part of the story. If the flow field through the coffee is preferentially through only part of the coffee bed, then you will overextract that portion and underextract the rest. Use of VST baskets ensures that you do not preferentially extract only a portion of the coffee. Use Vince Fedele's coffee refractometer to measure extraction yield if you can. You should be able to get extraction yields of around 18-20% at 50% brew ratio (ratio of dry coffee to beverage weight). Weigh coffee dose, final beverage weight, measure extraction time required to get the brew ratio you like (I prefer 55% as a starting point). Write down the extraction times and observe their variation. If you are controlling dose and beverage weight, then you should see extraction time consistency on the order of 2 seconds. Differences mean that you are channeling, and overextraction occurs at the channnels while underextraction occurs everywhere else. E-61 style grouups are really tolerant due to their slow pressure ramp. Non-e-61 groups channel more easily if there is not a means for slowing pressure rise sufficiently - so-called soft preinfusiion systems or manual preinfusion like on paddle group Marzoccos. Reduction of brewing pressure may help you with microchanneling and you will know because your extraction times will get more consistent and taste will improve.

-Greg