JDHarding Senior Member Joined: 31 Aug 2007 Posts: 1,099 Location: WA, USA Expertise: I love coffee
Espresso: Ascaso Steel Pro PID Grinder: Nuova Simonelli MDX,... Vac Pot: None Drip: Hario v60 Roaster: Behmor, Fresh Roast
Posted Tue Aug 30, 2011, 5:46pm Subject: Ascaso has too much pressure? (Solved)
[ Update ]
Things have changed since I originally wrote this post. I now own a Nuova Simonelli MDX grinder and my shots are far superior to those I pulled with the Virtuoso. The early blonding is a thing of the past. I still feel my machine has too much pressure, and ordered a pressure gauge kit to see how much pressure I really have.
[ Original Post ]
I've been away from espresso for a few months, and decided to come back to it recently.
Some preliminary information is probably ideal, so here goes:
- I own an Ascaso Steel Uno Pro with PID. Very new, only 5 or 6 months old. Has been descaled twice in that time, and regularly blackflush-cleaned every week. - I'm an experienced espressogeek, going on 5 years experience. - My grinder is a modified Baratza Virtuoso, with factory-installed shim upgrade, which makes it grind 20 times finer than original factory sold. - The beans are freshly purchased Red Bird espresso blend. Only 7 days old.
What I've noticed as I return is that my machine seems to have too much pressure while brewing. I've tried various grinds and they all seem to lead to early blonding. I've tried different tamping methods, but that too doesn't fix the problem. It blondes about 5 seconds into the shot. The only thing that doesn't make it blonde early is choking the machine.
I think the ascaso machines have the pressure set too high. This has happened on my Ascaso Dream as well. The machine hates pretty much every grind I try, other than choking the thing. They say they're 18-bar pressure from the factory, but I think the overpressure valve is too tight and not releasing the pressure properly.
I've located what I think is the OPV valve. It's next to the boiler, and is connected to the backflush pipe, or whatever you wanna call it. It's a hallow piece of brass pipe, maybe 2 inches long, with a threaded screw connected to a hose that leads into the drip tray. The part that's threaded has about 1 inch worth of threading, so I assume this is for adjustment purposes. When I took it apart it had a spring inside, and I know OPV valves are spring loaded. I'm guessing tightening it will compact the spring, which is pressed against the release, which will cause more pressure, and loosening it will uncompress the spring, which will decrease pressure, right?
My question is.. should I get a pressure kit and try tweaking the machine's pressure?
JDHarding Senior Member Joined: 31 Aug 2007 Posts: 1,099 Location: WA, USA Expertise: I love coffee
Espresso: Ascaso Steel Pro PID Grinder: Nuova Simonelli MDX,... Vac Pot: None Drip: Hario v60 Roaster: Behmor, Fresh Roast
Posted Fri Sep 23, 2011, 3:23pm Subject: Re: Ascaso has too much pressure?
I finally got my Ascaso pressure gauge kit and screwed it onto the portafilter.
It reads 15 bars of pressure. I tweaked what I thought was an adjustable OPV inside the machine, but tweaked it too far and it opened and water went squirting everywhere. Adjustable it ain't.
I guess 15 bars is probably okay, though not good for pulling ristrettos, but I can't adjust it to 9 bars.
JDHarding Senior Member Joined: 31 Aug 2007 Posts: 1,099 Location: WA, USA Expertise: I love coffee
Espresso: Ascaso Steel Pro PID Grinder: Nuova Simonelli MDX,... Vac Pot: None Drip: Hario v60 Roaster: Behmor, Fresh Roast
Posted Fri Sep 23, 2011, 4:14pm Subject: Re: Ascaso has too much pressure?
Grr! :P
The OPV can be adjusted so the bars is 12, but that's as low as it'll go before it opens and I get water everywhere.
The spring is so tightly packed in there.. I wonder if I can trim some of the spring off? Would that work?
Update: I cut a little bit of the spring off, and the pressure dropped to 13 bar. So I guess all I gotta do is trim the spring down till I reach 10 or so bar, then adjust the OPV down to 9 bar.
Posted Sat Sep 24, 2011, 8:28am Subject: Re: Ascaso has too much pressure?
Keep in mind that many entry level machines don't even have OPV valves on them and are capable of excellent espresso. I've spent lots of time experimenting with brew pressure and found that really, in the larger scheme of things, it doesn't really matter. Yes 9-bar can be a little more forgiving, but espresso at 10-12 bar is just as tasty and not too much harder to manage.
I'd suggest a grinder upgrade...
For safety sake I'd highly recommend you get a manual or some kid of prints for your machine, remember espresso machines heat water and pressurize said water, and if not working properly could lead to serious personal injury. Be careful when making repairs and be sure you know exactly what you're doing.
JDHarding Senior Member Joined: 31 Aug 2007 Posts: 1,099 Location: WA, USA Expertise: I love coffee
Espresso: Ascaso Steel Pro PID Grinder: Nuova Simonelli MDX,... Vac Pot: None Drip: Hario v60 Roaster: Behmor, Fresh Roast
Posted Sat Sep 24, 2011, 12:50pm Subject: Re: Ascaso has too much pressure?
I forgot to write down that I got a grinder upgrade since posting this. A Nuova Simonelli MDX. I'll never have to hear "get a different grinder" again. ;P
JDHarding Senior Member Joined: 31 Aug 2007 Posts: 1,099 Location: WA, USA Expertise: I love coffee
Espresso: Ascaso Steel Pro PID Grinder: Nuova Simonelli MDX,... Vac Pot: None Drip: Hario v60 Roaster: Behmor, Fresh Roast
Posted Sun Sep 25, 2011, 12:12pm Subject: Re: Ascaso has too much pressure?
I cut the springs down and tightened up the OPV and now the machine runs at 14 bar when fully heated. I tried setting it lower, but the OPV started spewing water out of it and I wasn't sure if that was okay or not. If too much water goes through it won't go out the grouphead, it'll all go out the OPV and into the drip tray.
Is it possible to pull doubles and triples at only 9 bar?
JDHarding Senior Member Joined: 31 Aug 2007 Posts: 1,099 Location: WA, USA Expertise: I love coffee
Espresso: Ascaso Steel Pro PID Grinder: Nuova Simonelli MDX,... Vac Pot: None Drip: Hario v60 Roaster: Behmor, Fresh Roast
Posted Sun Sep 25, 2011, 2:40pm Subject: Re: Ascaso has too much pressure?
I think I just figured out why there have been numerous leaks from the boiler. I think the OPV is set too high, at around 18-bar from the factory, and that pressure is not being released, so it builds up inside the boiler and causes leaks. Especially when the machine is heating up and becoming stable and there's extra pressure due to the higher temp during startup. I always noticed leaks during startup, but not when things were stable.
I've since tightened the spots where it leaked, and brought the OPV down to 14-bar (eventually down to 9 bar) and haven't noticed any leaks so far.
Symbols: = New Posts since your last visit = No New Posts since last visit = Newest post
Forum Rules: No profanity, illegal acts or personal attacks will be tolerated in these discussion boards. No commercial posting of any nature will be tolerated; only private sales by private individuals, in the "Buy and Sell" forum. No cross posting allowed - do not post your topic to more than one forum, nor repost a topic to the same forum. Who Can Read The Forum? Anyone can read posts in these discussion boards. Who Can Post New Topics? Any registered CoffeeGeek member can post new topics. Who Can Post Replies? Any registered CoffeeGeek member can post replies. Can Photos be posted? Anyone can post photos in their new topics or replies. Who can change or delete posts? Any CoffeeGeek member can edit their own posts. Only moderators can delete posts. Probationary Period: If you are a new signup for CoffeeGeek, you cannot promote, endorse, criticise or otherwise post an unsolicited endorsement for any company, product or service in your first five postings.
= No New Posts since last visit 