Accumulator Tanks

la marzocco, synesso, simonelli, cimbali etc

Accumulator Tanks

Postby Ed Kaufmann on Sat Dec 27, 2008 12:55 pm

We have very inconsistent water pressure in our building. The brew pressure is all over the place and it is impacting the flavor and extraction of our shots in a negative way. I have tested everything on our machine so I am sure it is incoming pressure related. Do you think that an accumulator tank would be the best way to remedy this problem?

I have noticed that some places sell such devices for very cheap. I am not sure which one is the best or most practical and best value for my buck. Does anyone have recommendations? So far I have encountered Shurflo ranging from $55 to $7 on various websites. I also noticed that most of them say that they are for after the pump. That seems strange to me. I would think that you would want to control the pressure coming into the pump. Which size would do the job for a 3 group Synesso. Thank you.
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Re: Accumulator Tanks

Postby Ed Kaufmann on Sat Dec 27, 2008 9:39 pm

Here is a little more information about the situation. After speaking with a highly-respected coffee peer of mine, we realized there could be more to the story.

1. When I turn on a group, the pressure gauge slowly wanders fron 8 to 10 bar and back. If I turn on one of the bar faucets while the group is on, the pressure will jump all over.

2. Our cafe is on the ground floor of a 20-something floor apartment/retail building. My coffee peer thought that maybe the pressure was coming from above which might cause too much pressure.

3. I spoke with the superintendent of the building and he laughed as he said that they pump 120 psi of water through the main system of the building (we could almost use line pressure to pull shots! Ha Ha!).

What do I do if too much pressure is coming into my espresso machine pump. It seems like it might not be geared to handle so much pressure. Also, I can only imagine that if a few people flush their toilets at the same time, the pressure would drop and recover pretty drastically.

Here is what I am looking at.
http://www.espressoparts.com/product/90 ... _Tank.html
would something like this level out my incoming pressure? Thank you.
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Re: Accumulator Tanks

Postby Alistair Durie on Sat Dec 27, 2008 11:04 pm

Hi Ed,

Do you have water filtration? Everything I have to say assumes you do. If you don't, that's another topic though there is still relevant info for you here...

We've used these accumulator tanks for years. As a Synesso dealer we strongly recommend them with every installation we do. Operators who do not have them eventually install them when they start to have flow issues, fixing all water flow issues instantly. Every water filtration system should have one. Without it there will inevitably be minor or major pressure fluctuations, and filters will need changed more often. Yes, they will save you money too.

If you are totally limited to using a tank for your espresso machine only, we have used the small Shurflo 21 ounce model due to serious space restrictions. As espresso machines don't typically see a huge amount of flow, these little tanks may provide just the amount of buffer you need. Be sure to use a check (one-way) valve on the intake so that it is not trying to pressurize the whole system, just your espresso side (before the pump). Still, I recommend a larger tank.

The benefit of larger tanks (2 Gallon, installed after the filtration) is that you can buffer water to all your equipment (it will level out your whole system). This is what we recommend and not just because your equipment will enjoy good flow - but that in the long run you will save a lot of money on your water filtration cartridges. Here's why... generally the cue to change water filters is because pressure is dropping. If there is 60psi output from a filtration system with clean filters, when filters clog by only 50%, that could drop output to 30psi, and when you are running a couple of machines they will begin to starve - the filters must be changed even when they have another 4-8 weeks of good use left in them. The solution is to buffer the pressure with an accumulator tank, maintaining pressure and using the full life of cartridges.

If your pressure is above 90psi before your filtration its a good idea to install a pressure regulator to drop this down as caution to protect your filtration system and all its fittings.

Be sure your filtration is never running to any regular faucet (hand sink etc).

Install shut off valves everywhere.
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Re: Accumulator Tanks

Postby nick on Sat Dec 27, 2008 11:54 pm

Ed, aren't you guys running Synessos? It'd be easy enough to do a rough check on the line pressure by clicking the group switch over to the line-pressure setting.
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Re: Accumulator Tanks

Postby Ed Kaufmann on Sun Dec 28, 2008 3:59 pm

I have not used the pre-infusion feature on the Synesso to do a line check yet but I did disconnect the water line before the filter, immersed it into a pitcher of water and turned on one of the groups (per Mark B.). The pressure held perfectly...didn't even think about budging. I hooked the line back up and had the same problem as before. We might have room for a 2 gallon tank. Which tank would you recommend? We do have a few things running off of the same line and I think it would be smart to level out all of the pressure going to all of the machines.
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Re: Accumulator Tanks

Postby Rod Carmer on Mon Dec 29, 2008 12:07 pm

Ed, I would ask again if you have a filtration system in place? Alistair points are correct.

This is interesting. We have run into this situation many times when filtration companies put systems in place and not explain all the aspects that could be in play. We have several systems that target specifically this issue. For instance, our Lp500 system stores water in a atmospheric tank and a repressurization pump delivers a more consistent water pressure to specific points of use. This eliminates all issues of water use in other applications as well as poor water pressure from clogged filters. Skip Finley can answer more questions if you have any.

To answer your question specifically if you isolate your incoming water supply you can deliver a specific water pressure to all your points of use.

Sincerely, Rod Carmer
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Re: Accumulator Tanks

Postby Ed Kaufmann on Mon Dec 29, 2008 1:21 pm

We have inline filter cartridges installed by Intelly. I can't find a brand name on them. The fresh ones were installed about 1 month ago. I still gravitate towards too much pressure in the building. The model number of the filters is FC1068C Item # 300-07104. I actually bypassed the filter and had the same problem.
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Re: Accumulator Tanks

Postby terry on Tue Dec 30, 2008 8:41 am

Ed,

Accumulators with reference to the small units from Shurflo and Flojet are for use after a booster pump or water supply pump, such as a Shurflo 2088 series pump. These accumulators provide positive down-line pressure and keep the pump from cycling on and off.

The two gallon variety is actually more common as a expansion buffer used on hot water tanks. You can purchase one and most any big box hardware store, or your local plumbing supply.

My recommendation is to place the take 24" away from the espresso machine pressure pump. Make sure you use a one way valve on the inlet side of the tank, or the tank is useless. This should resolve any incoming water pressure fluctuations.

A fluttering gauge may also suggest that the pump bypass valve has failed.

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Re: Accumulator Tanks

Postby Rod Carmer on Mon Jan 05, 2009 2:56 pm

The model number of the filters is FC1068C Item # 300-07104.


Ed, I have been in the water filtration market for more than 20 years. I do not recognize the Manufacture or the Model number. If you had a picture I can give you more information on the dynamics of that specific filter.

Generally inline filters for Coffee are Granular Activated Carbon (GAC) or Carbon/Phosphate combinations. These are effective in reducing chlorine and turbidity. You wouldn't recognize a noticeable difference in pressure until the filter is "Loaded" up with sediment. Then it could reduce your pressure and flow.

Again, using an accumulator tank will only regulate the current incoming pressure. If you have inconsistent water pressure from day to day (One day 50 psi and the next 75 psi) accumulator tanks are not the answer. If you have fluctuating pressure from moment to moment (65 psi and ten minutes later 40 psi) accumulator tanks are still not the answer. Accumulator tanks will only reduce the fluctuations from second to second and ease the affects of water hammer.

To solve your problem you should isolate your incoming supply and maintain your water pressure to your specific desired pressure. Whatever that may be? What is the desired pressure you are looking for and what are some of the fluctuating pressures you have seen?

Thank you, Rod Carmer
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Re: Accumulator Tanks

Postby Ed Kaufmann on Wed Jan 07, 2009 8:06 pm

When I turn on one of my groups, the brew pressure gauge will read 9 bar at first, then after a few seconds, drop to 8 or 7.5, then spike up to 10 and stay there for a bit. This is all within a 25 second extraction time. I will get a picture of the filters soon but I agree, I don't think the filters have anything to do with the problem. I just got a "cash valve" from Synesso to level out the pressure variances. It hooks to the pump, I turn the pump up to 11 bar and regulate it back down to 9 on the brew pressure gauge using the adjuster on the cash valve for perfect espresso extraction. I am going to hook it up tomorrow. I will let everyone know what happens. I feel pretty confident that this will fix the problem.
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Re: Accumulator Tanks

Postby naznar on Tue Jan 20, 2009 8:09 am

I suggest a pressure regulator valve, they are kind of bell shaped, designed for pit installation to step down city pressure to individual residence pressure. They maintain outflow pressure as long as thier inflow is greater. They are dynamic and eliminate big spikes of 1bar down to mere tremors of about a 10nth of a bar, or a trembling on the needle of your synesso. They have adjustable outflow pressure so that you can set your line pressure to whatever you want. for a Synesso the lowest recommended line pressure is 4bar. A pressure regulator valve steps down line pressure and eliminates pressure swings. 7bar, 7.5bar, 8bar all come out the other side of your regulator valve 4bar, 4.1bar, 4 bar. I have noticed with stepping down my own synesso's to 4bars that the natural flutter of the rotary vanes is slightly greater, but then with the pump supplying more of the pressure i think it makes sense that its flutter is amplified. Or the flutter could be vibrations from the pressure regulator valve since i have them installed just directly before the pump without much water column do buffer vibration. These valves run around 50 dollars and can be picked up at any plumbing store. -joel courier coffee portland

and i would think that synessos "cash valve" is a pressure regulator valve.
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Re: Accumulator Tanks

Postby Ed Kaufmann on Tue Jan 27, 2009 7:35 pm

Joel, what you are describing is exactly what the "Cash Valve" is. It is specifically configured to fit on to the pump of the Synesso. It has definitely reduced pressure variances. Our brew pressure is much more stable though not perfect. Thanks for all of the advice.
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