Water pressure and the effect(s) it may have on rotary pump

Need help with equipment usage or want to share your latest discovery?
dk

#1: Post by dk »

Water pressure and the effect(s) it may have on rotary pump of a direct connect machine. I am a brand new owner of a Vetrano and I have not measured my water pressure and I am wondering if this may be necessary to do as well as install a water pressure regulator if it is necessary.

Are there any detrimental effects to the machine, pump, espresso etc. of water pressure that is too high or too low?
"Does the Sun Come up before that Doppio, I think not"

User avatar
cannonfodder
Team HB

#2: Post by cannonfodder »

Without a consistent input pressure, you will not get a consistent output pressure. I had problems with too much line pressure. My machine was set at 9 bar drawing from a static tank. When I hooked it up to a supply line at 70psi, my brew pressure shot off the gauge (12+ bar). I installed a heavy regulator to step my pressure down. I ended up at 25psi on the regulator. I readjusted the pump to 9.5 bar with a blind basket and I get 9bar at brew.

Others are better versed in the virtues of water, but if you have a water system that experiences pressure swings, you may want to put an accumulator tank. As long as you are taking the time to put in all the parts, you might as well toss in a carbon filter and softener if you have overly hard water.
Dave Stephens

kaioslider

#3: Post by kaioslider »

Hi dk,

Someone over at coffeegeek's forums is having a problem with the Vetrano leaking, and he's on his second machine. I suspect it's the line pressure, as far as I can tell, he has no regulator and is on town water. Is static water pressure is 4 bars, mine is just under 2 bars, so I thought this was confirmation of what I suspected, but another Vetrano poster says he as his static at 4 bars too with no issues, but has a regulator. My other guess is that there is a bouncing in the water pressure, non steady pressure, which may account for the difference between the two. I got a regulator valve, my biggest concern was that as other building occupants use water, my water pressure bounces. I figure my regulator is set at about 25 psi. For $25 I'd say add it to prevent any damage to a $1400 machine. The cg post is in the Espresso Grinders and Machines, but up to this point it hasn't been very productive.

Dan

User avatar
HB
Admin

#4: Post by HB »

kaioslider wrote:For $25 I'd say add it to prevent any damage to a $1400 machine.
My concern about very high static pressure is that the boiler refill solenoid would fail to close during an auto-refill, potentially in the middle of the night. The Elektra A3 labeling was most explicit about its requirements:

Image
They are clearly stated in the Owner's Manual too

Max pressure of 4 bar (static) and maximum of 1.5 bar when the pump is running. Those seem like reasonable recommendations for the Vetrano too. The evaluation model I have is hooked to a pressure regulator set to ~2 bar. If your water pressure is very low or varies widely (e.g., due to being on well water), an accumulator would help. I got one for the FloJet and it worked wonderfully at EspressoFest supplying two rotary pump espresso machines.
Dan Kehn

kaioslider

#5: Post by kaioslider »

I should also have mentioned that the poster I was referring to said this problem after he shut the machine off. It's one thing to have solenoids and switches, but if they need power..........

User avatar
HB
Admin

#6: Post by HB »

A "normally closed" solenoid only needs power to open, otherwise a spring holds it closed. I have read reports of some machines' grouphead solenoids dripping above 60 PSI, though the Cimbali Junior never complained about it (I had only one pressure regulator at the time and Junior lost). Either way, it seems prudent (and not costly) to install a pressure regulator.
Dan Kehn

dk

#7: Post by dk »

Thanks for the input I will be installing a pressure regulator just to be on the safe side.
"Does the Sun Come up before that Doppio, I think not"

User avatar
edwa

#8: Post by edwa »

cannonfodder wrote:I had problems with too much line pressure. My machine was set at 9 bar drawing from a static tank. When I hooked it up to a supply line at 70psi, my brew pressure shot off the gauge (12+ bar). I installed a heavy regulator to step my pressure down. I ended up at 25psi on the regulator. I readjusted the pump to 9.5 bar with a blind basket and I get 9bar at brew.
Is the heavy regulator you installed different than the one Chriscoffee sells? If so can it be found easily from a plumbing supply firm?

If I understand you correctly, once you install the regulator you need to readjust/recalibrate the pressurestat to fit your water supply. Regardless, of how the machine was set-up by the technicians? Is it enough to use the blind basket or do you need a pf with gauge?

User avatar
edwa

#9: Post by edwa »

From How do you descale a non-reservoir machine, ie. Vetrano?
HB wrote:It's easy. I added a tee and two stopcocks. The tee leads to a jug of descaler. To descale, I turn off the mains water stopcock and open the second stopcock leading to the jug. When the pump calls for water, it will draw from the jug.
Soooo, in times of desperation - like when the missus is in another remodel project and the water is turned off I can still have my Java by using a jug of water in place of the jug of descaler?

I thought going direct connect would be very simple; just tap into a supply, filter, and regulate the pressure to max out at no more than 30-35 psi. But, unless I misunderstand other posts the incoming pressure becomes another factor to balance in the equilibrium of grind, distribution, tamp, dose, temp, brew pressure, bean freshness, and water quality?

If so, is this true for both vibe and rotary pumps or just rotary?

User avatar
erics
Supporter ★

#10: Post by erics »

The pressure measured at the inlet to the espresso machine affects the pressure developed by the pump. The pressure developed by the pump is brew pressure, typically anywhere from 8.0 bar to 9.0 bar with 9.0 bar being a "favorite". One bar is about 14.5 psi (14.5038 psi) and the inlet pressure will affect the outlet pressure on a one for one basis. This pressure and any variance it may have has no influence on the pressurestat setting or vice versa.

Normal water pressure in a home is, say, 60 psi. However this can vary between 45 and 75 psi depending upon what other fixtures are in use AND whether or not your neighbors decided to hold a car wash fund raiser. This is why a pressure regulator set to maintain, say, 35 psi (or whatever the espresso machine mfg recommends) is a necessity. It is also a good idea, as you say, to install a filtration system and you might also need a water softening system in areas of hard water. Call your local water authority gurus and compare their numbers to the numbers found in this document and you can easily make an informed decision.

http://www.big-rick.com/coffee/waterfaq.html

The majority of all water pressure regulators have a port for attaching a pressure gage which measures the controlled pressure and the acid test for ANY water pressure regulator is how well it performs when other fixtures are operated simultaneously. Start pulling a shot and ask someone to flush a toilet. You MIGHT see a small blip (1 or 2 psi) that quickly returns to setpoint but that will have no effect on your product.

Eric S.