pumpkinscastle Senior Member Joined: 10 Jan 2008 Posts: 181 Location: Cincinnati, OH Expertise: I live coffee
Espresso: Quickmilll Vetrano Grinder: Mazzer Super Jolly
Posted Sat Apr 26, 2008, 2:56pm Subject: Plumbing in an espresso machine and line pressure problems...
I just plumbed in my Vetrano and found out that my line supplies between 4.5. and 5 bar of constant line pressure (as per the Vetrano's pressure gauge). When I pull a shot, the pressure raises to approx. 9.5 bar. Plus, the motor makes a slightly whining sound from when it starts operating (even before pressure is built up in the portafilter. I let the motor run for a while, so there is really no accidental air inside!
Should I get the pressure regulator from Chris' Coffee and/or should I adjust the pump pressure so that the output during a shot is not higher than 9 bar?
Also, is 4.5 to 5 bar on the water supply line harmful to the Vetrano's seals and valves? Does the pressure regulator help reduce stress from the line pressure? I know that after a while the pressure will build up again despite the regulator as it only helps diminish pressure during flow (correct?) I have found a couple of vague answers on home barista but none that satisfied me. I have emailed Mary at Chris' Coffee and will see what she recommends but maybe some people on here who have their machines plumbed in might have good advise too.
pumpkinscastle Senior Member Joined: 10 Jan 2008 Posts: 181 Location: Cincinnati, OH Expertise: I live coffee
Espresso: Quickmilll Vetrano Grinder: Mazzer Super Jolly
Posted Sat Apr 26, 2008, 3:29pm Subject: Re: Plumbing in an espresso machine and line pressure problems...
UPDATE: The whining sound does not stem from the pump. When I drain the hot water valve and the pump fills the boiler, it sounds normal. I assume that the whining sound comes from some sort of over pressure relief valve when pulling a shot.
Keepitsimple Senior Member Joined: 12 Sep 2006 Posts: 211 Location: UK Expertise: I like coffee
Espresso: Reneka Techno Grinder: Mazzer Mini-e
Posted Sat Apr 26, 2008, 5:17pm Subject: Re: Plumbing in an espresso machine and line pressure problems...
pumpkinscastle Said:
I just plumbed in my Vetrano and found out that my line supplies between 4.5. and 5 bar of constant line pressure (as per the Vetrano's pressure gauge). When I pull a shot, the pressure raises to approx. 9.5 bar. Plus, the motor makes a slightly whining sound from when it starts operating (even before pressure is built up in the portafilter. I let the motor run for a while, so there is really no accidental air inside!
Should I get the pressure regulator from Chris' Coffee and/or should I adjust the pump pressure so that the output during a shot is not higher than 9 bar?
Also, is 4.5 to 5 bar on the water supply line harmful to the Vetrano's seals and valves? Does the pressure regulator help reduce stress from the line pressure? I know that after a while the pressure will build up again despite the regulator as it only helps diminish pressure during flow (correct?) I have found a couple of vague answers on home barista but none that satisfied me. I have emailed Mary at Chris' Coffee and will see what she recommends but maybe some people on here who have their machines plumbed in might have good advise too.
The pressure regulator that I installed maintains a static pressure when there is no flow - it doesn't creep up. It's a fairly heavy duty brass Watts regulator installed into a 15mm copper pipe using compression fittings. I also installed a pressure gauge in it (there are blanked off ports for that purpose). It may not be a model that's available in the USA due to plumbing/pipe/statutory regulation differences. I don't know which regulator you are thinking of buying, but I'd get a good hefty one - you really want to be able to fit and forget it for a long time ! They all work on the same principle though. I set mine to output 4 bar, as my machine's spec is (from memory) between 2 and 6 bar. It also helps to iron out pressure changes resulting from water being drawn elsewhere in the house.
Your espresso machine should have a specified min/may pressure rating. Provided you are within the range it should not present any problem to the machine.
Opinions differ as to the ideal pressure at the portafilter. It may be slightly lower when pulling a proper shot than what you see with a blind filter, and some machines are reputed to lose some pressure between the gauge and the portafilter. Your 9.5 bar is already within the range people go for, but it's very easy with a rotary pump to tweak it to whatever is your personal preference.
Posted Sat Apr 26, 2008, 5:39pm Subject: Re: Plumbing in an espresso machine and line pressure problems...
Chris' Coffee should be able to advise about line pressure. I think the line pressure is important for the flow through with a rotary pump. 4-5 bar is not too high but if it fluctuates it affects the pressure through the pump. When adjusting the output pressure of my Vetrano's pump I also played with the setting of my in line regulator. I saw a direct affect of the pump pressure output with a change in line pressure. If you want to keep a constant output with the rotary pump I believe regulating the line pressure would be important.
The green zone of my Vetrano's pressure gauge is between 9-9.5 bar. That pressure, from my experience and what I've read, is considered a standard for good extractions. Lower or higher would tend to change the espresso character. It's all a matter of taste, though. Some really like the espresso from a low set pump pressure, some might like it high.
I had the whining too. I believe it comes from the lever actuated valves and springs. It sounds like it happens as the chamber fills and comes to pressure. I haven't gone to the extent of opening up the e61 and lubing the springs, stems and valves inside but I feel that if I were to do so the noise would go away.
I had squeeky steam and water knobs too. Opening those up and lubing them over a year ago stopped the squeeks.
pumpkinscastle Senior Member Joined: 10 Jan 2008 Posts: 181 Location: Cincinnati, OH Expertise: I live coffee
Espresso: Quickmilll Vetrano Grinder: Mazzer Super Jolly
Posted Sat Apr 26, 2008, 6:11pm Subject: Re: Plumbing in an espresso machine and line pressure problems...
Thank you both for your answers. Chris Coffee sells a pressure regulator that fits in between the John Guest fittings. It's not a heavy duty brass beast though but it might be enough.
The output pressure when extracting/backflushing is ok. I think you're right that 9.5 bar is still considered normal, although the green area on my gauge is between 8 and 9 bars. However, the espresso tastes great at 9.5 (as it does at 8.5-9).
The whining sound in my machine does probably not come from squeaky unlubricated valves as 1.) the machine is brand new and lubricated and 2.) I did not hear those noises when I had the Vetrano suck water from a makeshift water tank before I hooked it up.
Interestingly, when I turn the machine off and lift up the lever to pre-infusion stage, the line pressure drives water through the group and the whining noise is present.
DavecUK Senior Member Joined: 21 Sep 2005 Posts: 205 Location: UK Expertise: I love coffee
Espresso: Izzo Alex Duetto (serial... Grinder: Mazzer Mini E Roaster: Toper 1kg (sold) Gene Cafe
Posted Sat Apr 26, 2008, 6:36pm Subject: Re: Plumbing in an espresso machine and line pressure problems...
The whining could be a number of things, you have not provided enough information to help diagnose it. Most likely though is the balanced bypass doing it's job, your hearing it now, because it's unlikely the bypass had so much to do when you ran it from a bottle. The rotary pumps will take quite a wide variation in line pressure (because of the balanced bypass, whose job it is to try and maintain a constant pump head pressure, regardless of the line pressure, within certain limits). If you vary line pressure rapidly, then you will notice pump some fluctuation as the response won't be instant, but say one day your pressure is 1.5 bar and the next day 3 bar, your group pressure will be approximately the same on both days.
That said, your inlet pressure (if it is as you reported) is on the high side and it would be better if you reduced it to something around 1.5-3 bar.
Keepitsimple Senior Member Joined: 12 Sep 2006 Posts: 211 Location: UK Expertise: I like coffee
Espresso: Reneka Techno Grinder: Mazzer Mini-e
Posted Sun Apr 27, 2008, 2:18am Subject: Re: Plumbing in an espresso machine and line pressure problems...
DavecUK Said:
The whining could be a number of things, you have not provided enough information to help diagnose it. Most likely though is the balanced bypass doing it's job, your hearing it now, because it's unlikely the bypass had so much to do when you ran it from a bottle. The rotary pumps will take quite a wide variation in line pressure (because of the balanced bypass, whose job it is to try and maintain a constant pump head pressure, regardless of the line pressure, within certain limits). If you vary line pressure rapidly, then you will notice pump some fluctuation as the response won't be instant, but say one day your pressure is 1.5 bar and the next day 3 bar, your group pressure will be approximately the same on both days.
That said, your inlet pressure (if it is as you reported) is on the high side and it would be better if you reduced it to something around 1.5-3 bar.
That's an interesting observation about the by-pass maintaining constant pump output pressure regardless of the input, because mine won't. If I vary the input pressure (not rapidly) it directly affects the output pressure by the same amount. Are there 2 different types of bypass which work in different ways, or is mine faulty do you think ? (not sure of the pump manufacturer, as it has a Reneka sticker across it) I'd always been told that pressure in does influence pressure out, as the bypass only controls the differential across the pump, so have never thought there was a problem.
DavecUK Senior Member Joined: 21 Sep 2005 Posts: 205 Location: UK Expertise: I love coffee
Espresso: Izzo Alex Duetto (serial... Grinder: Mazzer Mini E Roaster: Toper 1kg (sold) Gene Cafe
Posted Sun Apr 27, 2008, 5:53am Subject: Re: Plumbing in an espresso machine and line pressure problems...
Keepitsimple Said:
That's an interesting observation about the by-pass maintaining constant pump output pressure regardless of the input, because mine won't. If I vary the input pressure (not rapidly) it directly affects the output pressure by the same amount. Are there 2 different types of bypass which work in different ways, or is mine faulty do you think ? (not sure of the pump manufacturer, as it has a Reneka sticker across it) I'd always been told that pressure in does influence pressure out, as the bypass only controls the differential across the pump, so have never thought there was a problem.
There are 3 types of rotary vane displacement pumps.
No bypass
Standard Bypass
Balanced Bypass
it's the Balanced Bypass that does the job of maintaining relatively standard pump head pressures, with variations in inlet pressures and only works within a specific range of inlet pressures (related to the size of the Balancing port). So yours could be faulty (doubtful, but it could be), or of a standard bypass type (unusual). Might be worth peeling off the sticker and seeing what pump you have. A lot of the serial numbers you need will be on the brass body though, so might be visible.
Cino Senior Member Joined: 25 Oct 2006 Posts: 68 Location: Georgia Expertise: I love coffee
Espresso: Old Krups Thermoblock Grinder: Rocky
Posted Sun Apr 27, 2008, 6:41am Subject: Re: Plumbing in an espresso machine and line pressure problems...
Rotary pumps are positive displacement pumps. They are designed to provide a constant volume of effluent, regardless of pressure head, at a specified rpm. Pressure is controlled w/ some form of overpressure relief valve. Line input pressure should have negligible effect on output pressure since the pumps, technically, are not providing a pressure boost, only volume. If you are seeing a variation in output pressure, the overpressure relief is likely to blame.
Also, sometime back, I had asked someone at Chriscoffee if line pressure could be used to fill the boiler without having to turn the machine on. I was told "no" because there is a valve that should prevent any water flow when the pump is not running. If what I was told is accurate, it sounds like you may have a problem with that as well.
Keepitsimple Senior Member Joined: 12 Sep 2006 Posts: 211 Location: UK Expertise: I like coffee
Espresso: Reneka Techno Grinder: Mazzer Mini-e
Posted Sun Apr 27, 2008, 8:43am Subject: Re: Plumbing in an espresso machine and line pressure problems...
DavecUK Said:
There are 3 types of rotary vane displacement pumps. No bypass Standard Bypass Balanced Bypass
it's the Balanced Bypass that does the job of maintaining relatively standard pump head pressures, with variations in inlet pressures and only works within a specific range of inlet pressures (related to the size of the Balancing port). So yours could be faulty (doubtful, but it could be), or of a standard bypass type (unusual). Might be worth peeling off the sticker and seeing what pump you have. A lot of the serial numbers you need will be on the brass body though, so might be visible.
Thank you for the explanation. I think you are correct, and it is a standard bypass rather than a balanced bypass pump, even if, as you say, this is unusual. I think it may be made by fluid-o-tech, although there is no manufacturer label on it, only "CO051 F05" stamped into it. The pressure adjustment screw seems to correspond to the type found on fluid-o-tech pumps fitted with a standard bypass.
Picture of pump (half) shown here. (Identical machine, but picture courtesy of a contributor to the toomuchcoffee forum.)
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