D4F Senior Member Joined: 15 Mar 2012 Posts: 1,194 Location: USA Expertise: I like coffee
Espresso: Gaggia Classic PID Grinder: Preciso
Posted Wed Jun 13, 2012, 1:47pm Subject: Re: Gaggia SBDU Preheat PID Temperature Recovery and Stability
Andy, I see that you are putting Gaggia machines up for sale, and looking at Hx and DB. You might even get one with a PID? What will happen in the Gaggia Universe? :)
D4F Senior Member Joined: 15 Mar 2012 Posts: 1,194 Location: USA Expertise: I like coffee
Espresso: Gaggia Classic PID Grinder: Preciso
Posted Thu Jun 14, 2012, 8:09pm Subject: Re: Gaggia SBDU Preheat PID Temperature Recovery and Stability
Andy, I mounted a Polder digital thermometer. For my first attempt I used heatshrink tubing and mounted the thermistor on the front steamvalve to boiler bolt. I am not sure how valid the mounting point is, but it works. I have a PID sensor temperature of 214F and the Polder is 202.5 - 204F. These temperatures are when the machine is 15 - 20 minutes stable. Do you have an idea of a fairly stable temperature that you might try to have prior to hitting the steam switch starting your sequence?
Posted Thu Jun 14, 2012, 9:10pm Subject: Re: Gaggia SBDU Preheat PID Temperature Recovery and Stability
D4F Said:
Andy, I see that you are putting Gaggia machines up for sale, and looking at Hx and DB. You might even get one with a PID? What will happen in the Gaggia Universe? :)
Well ... so far nobody has been interested in buying (price probably seems high, since beatup units show up all the time for very cheap - but mine are all in perfect order with good pumps and boilers etc.). And besides, I am in no danger of running out of gaggias ... I have a classic, two OWC, a coffee, a new baby and two carezzas. Actually ... since I've been experimenting with steaming milk lately... I've been thinking I should just set two machines up next to each other, one dedicated for steaming and the other for pulling shots and call it a double boiler for 1/10 the cost.
The vivaldi II just really does speak to me - and I'm thinking plumbed in would be pretty nice - and a plumbed in HX seems even nicer in terms of the water always being fresh. Do you get that slime in your water reservoir if you don't scrub out the tank every week or two? Just seems like having fresh water always going through an HX would have to make a better tasting espresso. \
But the past week or so I have stopped leaving water in my reservoir --- I empty it out when I'm done and then fill it fresh before a session and flush plenty through the boiler before I pull my morning shots. Is that nutty? It seems to taste better - or is it all psychological?
Posted Thu Jun 14, 2012, 9:35pm Subject: Re: Gaggia SBDU Preheat PID Temperature Recovery and Stability
D4F Said:
Andy, I mounted a Polder digital thermometer. For my first attempt I used heatshrink tubing and mounted the thermistor on the front steamvalve to boiler bolt. I am not sure how valid the mounting point is, but it works. I have a PID sensor temperature of 214F and the Polder is 202.5 - 204F. These temperatures are when the machine is 15 - 20 minutes stable. Do you have an idea of a fairly stable temperature that you might try to have prior to hitting the steam switch starting your sequence?
Not sure I follow ... you said "thermistor" and that is something else - I think - or is that what the polder is using? I thought it was a thermocouple ... but if it is a thermistor that would explain why you can't just twist the ends of the wires together if the bead breaks like you can with a regular thermocouple wire.
I don't like putting the bead on the top of the boiler - but it is odd that you are only reading 202F ... I think if I were reading 215 at the regular thermostat mount (on the side of the boiler) I would be reading hotter than that at the top. (just thought of something though - When I'm getting my boiler up to target temp, I am in the habit of pressing both steam and brew with the steam valve closed and letting it run until the pump locks up so I know the boiler is really full right up to the top - and then I have to add a lot of heat to bring it back up to temp)
If I were going to mount the bead up top, I would (and have) simply put a dab of heat sink paste on the tip and push it under the thermofuse that is clamped on top. When I put a thermocouple bead there I usually read around 220F when the side of the boiler is reading 215F.
When I switch between machines (even though I have put a Polder thermometer on just about all of them) it is always a little different temp reading to get the right temp at the brewhead. Depending on how well I got the thermal connection between the bead and the metal side of the boiler - or what position - or the difference in stainless cabinet of the classic vs the plastic cabinet of the baby.
But I typically find I like to warm the machine up (but 10 minutes is enough for me - because I'll take it up to steam temps a couple of times and let it coast back down while flushing steam through the PF to really warm everything up). And when it's warmed up ... I'll probably find the temp where I see steam flash when I blip the brew button (this is usually above 235F - if I've flushed in the last minute or two I have to hit about 242F before I see steam bursting from the brewhead when I blip the brew button). So I will use that as an indicator of being warmed up ... and the quick flush starts the temp falling a bit. Then I try to settle in around 222F or 225F (depends on the machine).
But if the machine had been sitting there idling for 10 minutes and I wanted an espresso right now -- if the thermometer was reading anywhere between 212F and 218F I'd probably pop in a prepped basket and pull a shot without fussing much. If it were at 212F I'd probably hold the steam switch for 6 seconds instead of 4 before I started the shot.
But in actual practice ... if I suddenly had the hankering for a shot of espresso, the cup probably wouldn't be hot enough - so I'd probably heat the Gaggia up a little hotter first (235 or so) and blip a blast of hot water into the cup and then weigh and grind my coffee and dose-distribute-tamp. (less than a minute) and I'm in the habit of hitting the steam switch for a couple of seconds once or twice during the basket prep. So I'd be aiming for 221-222F on the baby or carezza (plastic case) or 225-226F on the Classic because (on mine at least - mine is old and doesn't have the insulators that the new ones have) the case really sucks a lot of heat away from the boiler.
Just test with the styrofoam cup - that's even better than the thermofilter for getting the temp at the instant you hit the brew switch (the thermofilter has to warm up for a few seconds so the very start of the pull is not accurate read) --- but the styrofoam cup can't tell you much about the drop in temp during the pull because the water is flowing so much faster than it would in an actual shot. But you can experiment with pulling a flush, waiting two minutes (or however long a recovery time you want to test) and find what temp on the Poulder Thermometer gives you an initial brew blast of 200F into a styrofoam cup. Because my temps are not going to match yours - different thermometers, mounted in different place on a different (mine is old) Classic. (I say different thermometers - even though same model - it's a $10 thermometer - I only care about using it as a relative measure, but I wouldn't expect two of them to read identical temps at $10 a pop. But once I know what it reads to give me 200F at the brew head measured by my better thermometer - then it is pretty consistant at always giving me the same information).
D4F Senior Member Joined: 15 Mar 2012 Posts: 1,194 Location: USA Expertise: I like coffee
Espresso: Gaggia Classic PID Grinder: Preciso
Posted Thu Jun 14, 2012, 9:51pm Subject: Re: Gaggia SBDU Preheat PID Temperature Recovery and Stability
AndyPanda Said:
Well ... so far nobody has been interested in buying (price probably seems high, since beatup units show up all the time for very cheap - but mine are all in perfect order with good pumps and boilers etc.). And besides, I am in no danger of running out of gaggias ... I have a classic, two OWC, a coffee, a new baby and two carezzas. Actually ... since I've been experimenting with steaming milk lately... I've been thinking I should just set two machines up next to each other, one dedicated for steaming and the other for pulling shots and call it a double boiler for 1/10 the cost.
But the past week or so I have stopped leaving water in my reservoir --- I empty it out when I'm done and then fill it fresh before a session and flush plenty through the boiler before I pull my morning shots. Is that nutty? It seems to taste better - or is it all psychological?
Scary thought, but I almost suggested that you use two machines, one for steam. I actually thought of getting an old/inexpesnive one for that. I wish there was an way to keep the boiler full, or know the water level. It would be easy to run out of water if you did much steaming, unless you always refill after each use and then limit the time of use. Of course, not as much problem with the larger boiler.
Also had the slime question today. I cleaned my tank and it was slick. Unfortunately, I already encountered that on my old Delonghi, and did not find any clear answer. Interesting search on CG with words water and slime. Lots of problems and talk, no real answer. I an not sure how to deal with it. You clean the tank and wipe the tubes, but that slime has to go up into the machine to some point. It is on the tubes, so on the inside as well. Probably serves as pump lube!
D4F Senior Member Joined: 15 Mar 2012 Posts: 1,194 Location: USA Expertise: I like coffee
Espresso: Gaggia Classic PID Grinder: Preciso
Posted Thu Jun 14, 2012, 10:19pm Subject: Re: Gaggia SBDU Preheat PID Temperature Recovery and Stability
AndyPanda Said:
Not sure I follow ... you said "thermistor" and that is something else - I think - or is that what the polder is using? I thought it was a thermocouple ... but if it is a thermistor that would explain why you can't just twist the ends of the wires together if the bead breaks like you can with a regular thermocouple wire.
IIRC digital thermometers are thermistors. I found that before and posted about thermistor, thermocouple, and resistor sensors.
I may try it under the fuse. You had mentioned once that the bead did not like pressure and I was concerned about any clamping. I also wondered about the wire insulation, but suspect that the short portion included with the bead, before joining, is teflon or similar coated - high temperature tolerant.
I will have to think more about the rest of the post in the morning after espresso to think more clearly.
I hope that you are still considering pulling shots as discussed above.
"digital Thermometer" (as far as I believe) simply means something with a digital readout that tells you the temperature - and I don't believe it implies anything at all about what method it uses to determine the temp.
D4F Said:
I may try it under the fuse. You had mentioned once that the bead did not like pressure and I was concerned about any clamping.
The bead will shatter if you clamp it under a screw head or between two pieces of metal and tighten it down. That's why I didn't suggest putting it under the screw that holds the fuse - I suggested pushing it under the fuse. The fuse is wrapped in soft rubbery sleeve and you don't even have to loosen the screw or clamp -- simply push the bead underneath the fuse so that rubbery sleeve is pressing the bead against the metal of the boiler, it isn't very tight at all and with a dab of heatsink compound it'll slide right in and read pretty consistently. At least on any of my machines it has worked that way. I've only used that spot with my other thermometer - with the very long wire. But that little Polder thermometer has a very short length of wire - I guess you are mounting the readout up higher than I did.
I should get Poulder to pay me a commision - the only responses I got to my FS post have been about 6 emails asking where to get the thermometer and how to mount it.
Posted Fri Jun 15, 2012, 7:26am Subject: Re: Gaggia SBDU Preheat PID Temperature Recovery and Stability
AndyPanda Said:
But the past week or so I have stopped leaving water in my reservoir --- I empty it out when I'm done and then fill it fresh before a session and flush plenty through the boiler before I pull my morning shots. Is that nutty? It seems to taste better - or is it all psychological?
Andy, I don't know if this will answer your question, but I'll never forget when an old friend who is retired from the local water company told me that I would never drink tap water if I ever got a look at the inside of the city water tank (on the tower). Let your imagination be your guide here.
Posted Fri Jun 15, 2012, 8:31am Subject: Re: Gaggia SBDU Preheat PID Temperature Recovery and Stability
Oh ... I know. Years ago I worked for a company that built municipal water systems all over the world (the engineers affectionately called them "turd twirlers")
I've had RO system under my sink for 40 years and I love the taste of RO water. No matter how many posts I read about how "flat" it tastes and how much better spring water or mineral water tastes - bottled water always tastes "dirty" to me (most bottle water has that "garden hose" taste) compared to the clean taste of RO water. However I have read so much about RO being acidic (and I can measure it with test strips - it is acidic) and being bad for boilers (especially Gaggia with the brass, chrome, copper and aluminum boiler mix - recipe for corroded aluminum). I experimented with a pinch of baking soda ... and a pinch of celtic sea salt - or this stuff from Utah called "Real Salt" (ancient sea salt with lots of trace minerals). And there is a huge improvement in the taste of espresso when I add enough of the mineralized sea salt to get the balance right without tasting salty.
But the past few weeks, I bypassed the RO cartridge and now my city water (pretty soft where I live) goes through the whole series of filters and the final charcoal filter but not the RO. So far so good - tastes great - but I haven't lived with it long enough to see if it scales or not.
I've been tempted to go back to the RO but put a calcite filter in there to remineralize it a little. I find this whole subject very difficult to get clear answers about because there are so many sites selling "snake oil" -- and there are lots of very strong opinions -- it is easy to find posts saying RO water will kill you and just as easy to find posts saying how safe it is. But it is hard to argue with a test strip that shows 6 ph and a boiler made with copper and aluminum - and then again a pinch of baking soda - so many conflicting opinions to sort out.
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