Posted Mon Sep 27, 2004, 7:43pm Subject: Re: Can the pump pressure on the Isomac Venus be adjusted?
PID'ing it doesn't look hard
PID'ing it right, however, does look to be hard. The 'tail' version of PID's looked to be the most attractive to me, but too many long wires were involved, as well as a project box. Thats two things i hate.
There's room for a front mount, but I have reservations about hurting her look and feel on the top. The bottom, behind the splashplate, is too short by 25mm or so, based on most of the PID units i've found
The only place i can imagine sticking a PID, is on her side -- somewhere below the steam knob. I measured out the internals, and most units will fit nicely.
Before I go that far though, I want to try insulating the boiler and replacing the plate and screen on the grouphead. I *think* that should help a bit.
BTW, i found a dumb trick to get her hot faster -- I drop the PF on the grill and push the steam wand over it on high for a minute. Then I lock the pf in and run 6oz of water through the grouphead. (HX machines do it to cool down, why can't single boilers do it to warm up?)
She goes from cold to too hot to touch in a few minutes. Perfect.
Posted Tue Sep 28, 2004, 4:10pm Subject: Re: Can the pump pressure on the Isomac Venus be adjusted?
Oh yes the bimetal thermostat needs a kick and so do the cups as the tray does not keep them warm at all. So what i do is remove the PF (which i always keep in the GH loosely screwed in to keep hot) and run water into the cup until the boiler light comes on. In fact i learned that it is about 5-15 secs after an Illy cup is full that the light will come on. This gives me time to grind on my Rocky SD. I lock in PF once the light comes on and start the extraction after the light goes off. AnotherJim "learned me" the trick with the thermostat.
Love the Yemen Moka Sanani done in my GG/Stir Crazy setup. The Venus is at work so i roast 1 lb at home on Sundays to last me the whole week. The flavor is esp intense on TUE-THU then sorta gets slightly weaker. I keep the leftovers from the batch in the freezer among my coworkers hamburger patties and popsicles (ok ok a classier chick even has Haagen Dazs in there when not on the size 5 diet:))))
iZappa Senior Member Joined: 14 Sep 2006 Posts: 129 Location: Norway Expertise: I live coffee
Espresso: Isomac Millenium Grinder: Anfim Haus, Ascaso i-2,... Drip: French press will do Roaster: Gene Cafe
Posted Sun Jan 7, 2007, 4:34am Subject: Re: Can the pump pressure on the Isomac Venus be adjusted?
I have some concerns regarding this tweak. I tried it myself on my Venus a couple of months ago and the two major concerns which I realized was:
The pressure gauge is mounted directly on the boiler. Doesn't this mean that the gauge reads the pressure of the pump and not the actual pressure of water going through the puck. I'm thinking that it gives a fault reading of pressure in the puck.
If one tweaks the bypass valve and cuts down the spring. Very much hot water will go in circle from the boiler into the water reservoir and then into the boiler again. This leads to less temperature stability and causes the boiler to cool down during a shot. And especially for consecutive shoots.
The reason that I'm concerned with number two is that my temperature measurements of the Venus shows that it delivers a tad to low brew temperature in the first place, with brew temperatures from 93 - 89 degrees. If one just approaches the machine after it has been idle for a long period of time I've done measurements of temperatures down to 85 degrees. Thatís why I think emptying the boiler would cause more harm than good.
But if anyone have other ways of explaining this I'd be more that happy to reconsider my points.
Posted Wed Jan 10, 2007, 11:25am Subject: Re: Can the pump pressure on the Isomac Venus be adjusted?
izappa: 1) No. it gives the correct reading of puck pressure. The pressure of the pump on the boiler is what forces water through the puck ( and limited by the OPV ) 2) Yes. The reason for this is that Isomac are cheap bastards. every other configuration out there has the OPV valve BEFORE the boiler and a steam release valve on the boiler. Instead of doing that, Isomac merged the steam release and OPV valve into a single valve AFTER the boiler.
You only need to limit the pump to 9bars for ristrettos. A good espresso puck will be in the 8-10bars of resistance range. A good ristretto puck will create 11-14 bars of resistance - so you need the OPV to keep the pressure down.
The venus has a tiny boiler -- .3 liters. It also has a massive heating element. That said, you can't do back-to-back shots under any conditions -- but it only takes about a minute to get things stabilized again.
Yes. The sililcon tube goes into a T. the left of the T has a barb that can be tightened/loosened -- that is the OPV. The right of the T is the steam want path. The bottom of the T is the boiler feed.
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