First of all, when it comes to pressure, there are two pressures to be aware of. The Pump pressure (not shown on the espresso machine pressure gauge) and Boiler pressure, which is shown on the machine pressure gauge, and is our proxy measurement for brew temperature.
In the photo below, is the portafilter pressure gauge that I made for setting the over-pressure valve to adjust the pump pressure. For this machine I adjusted the pump pressure to 8.5 Bar, but the only way to measure it is with the portafilter gauge.
The boiler pressure, i.e., what we read from the pressure gauge on the face of the the machine, is adjusted by the adjustment screw on the Sarai pressurestat see photo in the next window. By adjusting the pressure in the boiler, we can control the temperature of the water used for brewing. The general range of temperatures for espresso are in the range of approximately 192-205 (deg F) or about 89 to 96 (deg C). On my machine, within the normal temperature range for espresso extraction, which can vary by bean variety, roast quality, and age of the bean, I'm, usually in to range of about 0.96 - 1.25 Bar. But personally, I don't adjust the boiler pressure (I mean temperature) my measuring it, but rather by the flavor of the extracted shot (bitter - too hot, sour - too cold). I hope that helps a bit.
kellogs Senior Member Joined: 28 Jul 2010 Posts: 6 Location: Sweden Expertise: I live coffee
Posted Sun Nov 6, 2011, 4:00am Subject: Re: Brasilia Cappuccino Del-1 Project
Thanks for your reply. I'm only getting my group head to around 70-75 °C (158-167°F). This machine has no thermosyphon the heating of the group is by the brass against the boiler (right?). I don't know what to do to get the temperature higher. Espresso at too low temp isn't really nice :D
Posted Sun Nov 6, 2011, 6:13am Subject: Re: Brasilia Cappuccino Del-1 Project
Have you adjusted the screw on the pressurestat?? If you look down from the top at the pressurestat, there is a slotted screw head. Turning it counterclockwise, will increase the boiler pressure, and therefore the brew temp. If adjusting the pressurestat has no effect, you may need to replace it... but first, make sure the "plumbing" is clean and not obstructed.
I have an identical machine, which unfortunately has a rupture in the HX. I have thus removed the boiler and will now need to open it. I would therefore like to know how you removed the boiler ends before I damage something:-) ?
Thanks! It was a fun project and the espresso I'm making in combination with the Pharos grinder is consistently great too!
Well........... that's a great question!
First - I would recommend you remove all of the connectors (elbows and T's) on each of the boiler end plates.
Second - you need to remove the two bolts (one on each end of the boiler) that hold the HX tube in place.
Third - get a rubber (or plastic) mallet (yep, that's right a rubber or plastic hammer).
Fourth - get to work! Use the hammer around the edges (lip) of the end plate, striking it in a direction away from the boiler body, parallel to it's long axis.
Fifth - if it doesn't come off easily, don't worry, it doesn't! Just get a bigger rubber hammer if necessary!
In all seriousness, that really is the way it's done, check this link, for corroboration. Just be careful not to distort the body of the boiler (it's pretty resistant to distortion, so this really isn't a problem). But you'll be surprised, it takes a fair amount of effort to get the end plates off, in order to open the boiler.
Of course, when you re-assemble the boiler, you'll want to get new gaskets (o-rings) for the boiler end plates, and for each end of the HX as well. Keep in mind, depending on the year and model, some of the boiler end plates have just one large viton o-ring each, whereas others have the viton o-ring, as well as a Teflon seal for each end plate, so take a look at it open before you order any parts for it.
Nice job Rick! I hate that steel screws are used where they are sure to rust. I just did a full tear down and rebuild of a Silvia because one of the screws on the boiler corroded off and she developed a leak. Like yours, SS screws now are doing the holding duty. There is no excuse for steel screws in high potential corrosion use.
I was lucky though, the screw heads broke off high enough, I could use some very fine oil down into the threads and with the use of a vise to hold the screw ends, they came out.
Looks nice! I am sure you will enjoy that machine a whole lot more knowing every little thing about it. Nice job!
In real life, my name is Wayne P.
Feed the newbs, starve the trolls and above all enjoy what you drink!
Thanks! It was a lot of fun, and except for those two rusted screws, pretty straight forward. Believe it or not, the thing I'm enjoying most about it on a daily basis, is the custom tuned steam tip... It's become effortless to make good quality micro-foam and I'm able to pour latte art with every cup (getting pretty good at it too :). I also replaced every structural and component support screw with stainless steel screws (and washers) while I was at it.
Since you just rebuilt a Silvia, I thought I'd point you in the direction of a Blog that I wrote describing the Silvia project that I did a while back. It was incredibly challenging for me, and there was a huge learning curve regarding the electronics that I added as well as the programing that was involved.
But then, It was a great project that lasted well over a year, I made some good friends in the process, and I never lacked for something to do!
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