# Low brew pressure on E61



## LeeAlbert (Nov 8, 2018)

Hi all,

Need some advice on a 2elle Elisa please. It's an E61 grouphead with a 2L single boiler Hx, water is provided via reservoir.

Issue is that I'm having low brew pressure (about 5 bar with a blind filter)

So far these are the steps done

1) changed pump (ulka ex5)

2) changed OPV spring and seal, adjusted OPV

3) checked valves for scale

4) checked pump, is delivering 14 bar pressure

Additional info

1) brew pressure gauge reads 2 bar when using an open portafilter

2) flow rate of 440 ml/Minute with no Portafilter

3) no flickering of the brew pressure gauge

4) pressure verified using a pressure meter attached to portafilter.

Any input would be appreciated.

Thank you.


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## DavecUK (Aug 6, 2013)

I don't quite understand point 4?? If that's ok why the low pressure against s blind filter, because that's what a portafilter gauge is.


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## 9719 (Mar 29, 2015)

@DavecUK is your man, may ask for more info and possibly photos to help with diagnostics. Others might also be able to advise, I'm sure someone can help you.

To late he's already up and about


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## LeeAlbert (Nov 8, 2018)

Hi Dave, thank you for the kind reply.

Sorry I wasn't clear enough. For point 4 of additional info: Suspected that the brew gauge on the machine was off, so the pressure was verified by screwing on a pressure meter on a spouted portafilter. The pressure was verified to be low (5 bar)

As for steps done. Attached a pressure meter direct to the pump, it reads 14 bar.


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## DavecUK (Aug 6, 2013)

Well there are 4 things to check that can give low brew pressure *against a blind filter* when the pump is delivering 14 bar (especially when you have a new pump). I'll put the 2 obvious ones first.

1. Water is flowing out of the group vent valve (but you would see it)

2. Water is flowing from the expansion valve you call the OPV. This would be obvious if yours drains to the drip tray as you would see very heavy flow...if it drains to the tank, you may not realise it's hapening

3. The autofill valve to the boiler is opening or partially open and water is continually filling the boiler (this would give you about 4 or 5 bar against a blind filter), but fairly quickly your boiler would overflow. Unless you use lots of hot water from the machine.

4. Fracture in HX pipe within boiler...problems would be same as above

Apart from the above, there is really no other reason. I assume you have done the tests properly and that water flows normally and immediately from the group when you lift the brew lever. Post up a Video with sound.


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## LeeAlbert (Nov 8, 2018)

Strangely none of the above.

Machine isn't with me at the moment, but will get a video up during the weekends.

Another observation I forgot to note, the boiler pressure doesn't increase abnormally, it's still normal with max pressure set at 1.2 bar. Autofill valve was also checked.

Yes the water flows normally and immediately upon lifting the brew lever.

It's a rather puzzling case for me this.


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## DavecUK (Aug 6, 2013)

LeeAlbert said:


> Strangely none of the above.
> 
> Machine isn't with me at the moment, but will get a video up during the weekends.
> 
> ...


Either your machine is in some way very unusual, or there is something you have omitted to observe/mention


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## LeeAlbert (Nov 8, 2018)

Took it to an espresso doctor and all of us were scratching our heads in the end. No leaks anywhere, pump runs fine, machine looks clean inside, not really any scale build up, but it just does not generate enough pressure at the group. He's suggesting to try to change it from a vibe to a rotary. Something about the vibe pump not generating enough flow rate.


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## DavecUK (Aug 6, 2013)

LeeAlbert said:


> Took it to an espresso doctor and all of us were scratching our heads in the end. No leaks anywhere, pump runs fine, machine looks clean inside, not really any scale build up, but it just does not generate enough pressure at the group. He's suggesting to try to change it from a vibe to a rotary. Something about the vibe pump not generating enough flow rate.


Nope, nonsense...


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## 4085 (Nov 23, 2012)

Was this doctor in Harley Street or Haley Street


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## ajohn (Sep 23, 2017)

Usually machines have 2 pipes going back to the tank - one draws water the other puts back what the OPV dumps. Have you checked for water flow in that one showing it's opening?








As over pressure valves go the ones fitted in espresso machines area bit naff compared with other areas. All tend to do the same thing - they have a cracking pressure - they relieve the pressure but as there is flow out the pressure changes. The higher the flow the more the change. The numbers seem to be rather extreme in this case. I'm inclined to wonder about how the OPV was set in the first place. I wouldn't expect readings during what is effectively back flushing to match when the same OPV setting is used to brew. I have seen a significant difference measuring with a portafilter pressure gauge - higher reading, probably a couple of bar. Hard to say as the gauge was past the point where it was intended to be used. Initially I used a gauge of a gaggia and the readings didn't make much sense so finished up buying a proper pressure gauge for fluids.

John

-


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## DavecUK (Aug 6, 2013)

To OP, the only time I have seen something like this was when testing a Fracino which *everyone* thought was good and was providing very low brew pressure (and also low flow from an open group), but with the case off and tested it was all fine. I discovered that a new component they had added had moved the feed tube to the pump enough that is was bent and kinked when the case was put on.

*If all the other things are fine and as you say the pump produces 14 bar...remove the case and ensure the cold water feed tube to the pump is in no way kinked ...and whilst the case is off, touch nothing, but do a pressure test against a blind filter.*



*
*P.S It's also why I suggested you do a vid of the machine showing flow from the group and against a blind filter, as it's quite handy for diagnostics


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## LeeAlbert (Nov 8, 2018)

Really appreciate all the comments and help given. You guys have been awesome.

Thanks Dave, I'll get the video by this weekend and hope it helps.

Hi John, I'll check on that feed back to the tank when I'm back from a trip. Maybe measure amount of water fed out of it on a blind filter vs open grouphead.


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## LeeAlbert (Nov 8, 2018)

I've posted up a few videos,

1st is open group, the white pipe is the outlet back to the tank from the expansion valve/OPV.






The water input isn't kinked, flowrate out the group was 440ml per minute. I'm not sure if that is considered high or low.


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## DavecUK (Aug 6, 2013)

Flow rate normal, but from the pressure your getting and the lack of flow from the expansion tube and the fact that it's a new pump....I would Hazard a guess that the water is entering the steam boiler as well. That's the sort of reading you get when that happens.....with coffee in the portafilter it would be even lower. I would imagine that 2 litre boiler is gradually filling up.

P.S. Probably faulty autofill solenoid valve.


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## LeeAlbert (Nov 8, 2018)

Thanks Dave, I've ordered an autofill solenoid valve, hopefully it solves the pressure issue. Will update when I get it.


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## caffeinegeek (Aug 29, 2018)

There are more knowledgeable people here than me but I have been all over my old Fracino. I regard it as having a cloned E61 head with their added solenoid removing pressure to drain. I didn't spot it straight away but what surprised me the second time I was dissasembling their group head was the tiny circular stainless steel filter screen in a chamber on the top after the brew water inlet. This is followed by a jet with a VERY small orifice of about 0.7mm dia. This was a surprise when you look at the size of everything else. But explains how the small amount of brew water passing through the portafilter basket is kept at near constant pressure during the shot pull. The gauge is on the brew water flow output before the jet. I only see a small change in pressure when a shot is pulled and I can now see why. It also explains where the generally quoted figures of expected water volume come from when a shot is pulled with an open portafilter. The brew water volume delivered is determined by the pressure set on the pump, the size of the jet and the time water flows. If we time the flow over 25 seconds for say 9 Bar pressure, the amount of brew water delivered to an open filter should be similar machine to machine. This also assumes the pump pressure control is good and maintaining its pressure when loaded. A good point was made about mains water inlet pipe kinking, This aspect of the design on my Fracino was really bad and took some time to get a kink free routing. A rotary pump using a mechanical pressure off loading valve needs the pump to be fully charged on the water inlet side to allow it to regulate the set pressure under all load conditions. A kinked pipe could starve the pump and reduce outlet pressure when needed for the shot.

I agree that if pressure is not reaching the filter basket it can only be lost in a few circumstances - The pump pressure is 'sagging' which should be evident on the gauge, water is being bypassed via the OPV, water is going to drain (visible) or if the group head has this small jet like mine it could be partially blocked? On my Fracino I had to buy an unusual long reach metric socket to remove it for cleaning.

I've been looking at these pressure gauge modded blind portafilters and I'm not happy with them for my Fracino? When my shot starts, the flow meter is expecting some (small) flow as brew water is sent through the charged puck. If no flow is sensed, my machine goes berserk into alarm mode and the same thing happens if I try a rubber blanking disk. I've concluded the only way to get a useful pressure reading is to measure pressure in a fully charged portafilter as it is passing brew water. Unless you drill holes into the group before the filter basket you can't do this. One way I'll try is to fit a needle valve after a pressure gauge fitted on a blind portafilter. For my test I shall swap out a 3/8" spout. The out flow from the needle valve can then be adjusted to be the 25 second discharged shot volume. The presssure reading will then be more representative of real life because it will correctly show if the pump pressure is sagging (in my case) after the flow jet, whilst my machine is working under its normal conditions with a measured flow and no alarms. By adjusting the needle jet I should be able to simulate finer coffee grind to see how well the pump pressure into the filter basket holds up.

These blind portafilters are everywhere on Fleabay with just a pressure gauge attached. Somebody please tell me why these are so popular for fault finding when they don't allow normal water flow? If other group heads have a small jet orifice like mine, there will be an unstable pressure reading as the brew water through this jet is pushing against a relatively large volume of trapped springy air.


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## LeeAlbert (Nov 8, 2018)

Hi all,

I've got some updates and it's good news.

After changing the autofill solenoid, cleaning the grouphead, and back flushing, the pressure went all the way up to 12bar. After adjusting the OPV, I've got 9bar and am a happy camper. Machine now makes great coffee and I've ordered some nice beans.

Thank you all for your help, you guys have all been wonderful and I'm truly appreciative of all the help you guys have graciously given. Looking forward to interacting more with all of you.


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## HowardSmith (Jan 21, 2018)

LeeAlbert said:


> Hi all,
> 
> I've got some updates and it's good news.
> 
> ...


what a result, good to see when have some very knowledgable people willing to help for free on here.


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## DavecUK (Aug 6, 2013)

It also shows what I have been banging on about for a while now...a Video with sound is worth a thousand words, easy diagnostics once I saw the Video.


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