# Pre-infusion question (plumbed vs non-plumbed)



## Pooper (Jun 14, 2015)

I'm about to lay down some dosh on the Duetto, but just wondered if someone could explain the deal with pre-infusion with regards to whether the machine is plumbed in or not.

Is it correct to say that if you're just using the reservoir and NOT plumbed in, you don't get any pre-infusion?

I think I've read conflicting info across various sites, so I'd appreciate it if an owner could confirm what the deal is

Thanks!


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## WEJ (Apr 11, 2013)

I wasn't aware of this, but just switched mine on to try, and it seems that if you lift the brew lever to around 80 degrees, (pump is activated at around 90 degrees), then mains pressure water is released. That would be 7.5 bar in my house, according to the dial. No idea if that is accurate.

Thanks, new feature for me to play with!!


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## Dylan (Dec 5, 2011)

As WEJ mentions, the 'half way' point on an e61 lever will give you 'preinfusion' at whatever your main pressure is if you are plumbed in.

A tank fed e61 still has preinfusion but of a different type. As the vibratory pump activates and fills the lines and e61 with pressurised water the pressure ramps up to the set pressure, giving you a 'preinfusion'. As far as I know when you have a mains fed machine with a rotary pump this pressure build up is much quicker with the group fully open.

So both have preinfusion but of a different type.

See this thread for a more in depth explanation: http://www.home-barista.com/espresso-machines/what-makes-it-e61-group-t3728.html and http://www.home-barista.com/espresso-machines/pressure-profiles-preinfusion-and-forgiveness-factor-t647.html


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## Pooper (Jun 14, 2015)

As I've never had pre-infusion before, I'll see how I get along with the "non-plumbed in" pre-infusion. tbh, as it's a new machine for me, pre-infusion probably won't be one of the first things I'll be stressing over.


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## jesperzac (Sep 2, 2015)

I have an Alex Duetto v3 and have used un-plumbed pre-infusion ever since I got the machine a year ago. Whether or not it makes a difference on the end result I haven't tested.

However, only today I stumbled on below review by Clive Coffee where they state (in the very last remark) that it may actually damage the group head to use pre-infusion without being plumbed... Anyone care to comment?

Thanks in advance!

Best regards, Jesper

http://www.clivecoffee.com/learn/2013/03/second-lookduetto-v3-six-month-review/


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## Dylan (Dec 5, 2011)

It's actually a comment from someone rather than a statement by Clive Coffee, not sure if there is any real basis to the comment.

@DaveC tends to know these things.



> ANY TRADITIONAL E61 MACHINE (ROCKET AND QUICKMILL INCLUDED) MUST BE PLUMBED IN ORDER TO PRE-INFUSE PROPERLY. WHILE YOU MAY SEE A PRE-INFUSION OF SORTS UNPLUMBED, IT WILL RESULT IN A SIPHON LOCK IN THE BREW GROUP AND COULD POTENTIALLY DAMAGE IT.


But in addition to that, I have read that the 'preinfusion' of the lever at halfway on an e61 group is not much more than 'puck wetting' with very, very low pressure, and several threads on HB suggest it makes little difference or in fact damages the extraction.

When putting the e61 in fully on position, its design (with a vibe pump) ensure a pressure ramp up in any case, full pressure does not just hit the puck immediately. So even without using the half way point you are still getting a form of preinfusion.


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## DavecUK (Aug 6, 2013)

Dylan said:


> It's actually a comment from someone rather than a statement by Clive Coffee, not sure if there is any real basis to the comment.
> 
> @DaveC tends to know these things.
> 
> ...


1. There is some basis to the comment by Clive Coffee, but not quite for the reasons they think! If a machine is *unplumbed* and is a traditional HX machine, then allowing water to dribble from the group will at worst empty the HX unit within the boiler...but hey that's no biggie. It can't damage the brew group or anything else, however the machine will not work in the way intended/designed, especially with respect to temperature management.

However, and this is important....any machine with a single boiler or a *dual boiler* does not usually have a method to detect low water in the brew boiler, these type of machines have no autofill circuit/detection within these boilers. There is the potential for damage if enough water is run out. Admittedly this is unlikely in a preinfusion scenario, unless you forgot and left the machine in that state! You could of course get some air/headspace in the boiler of these machines, it also depends on the specific design of solenoid valve used and whether any air can get back from the group. These are not generally designed for situations, except in machines I have had some involvment with. Even then it's undesirable. e.g. the Expobar Dual boiler machine has definitely not been designed with this scenario in mind, The Rocket Dual boiler has some limited tolerance (very limited though) to this due to it's design. Duetto, Verona, Vesuvius, will all stand up to this much better, because of their design.

2. E61 preinfusion by a so called "middle lever position" is not part of the design feature of the group. it just happens to be a situation the group can be put into if the adjustment of the pump is such that it does not engage just before, or just as the top brew valve opens. The E61 preinfusion by design is a product of the small preinfusion chamber and valve spring just undet the cam chamber of the group.



WEJ said:


> I wasn't aware of this, but just switched mine on to try, and it seems that if you lift the brew lever to around 80 degrees, (pump is activated at around 90 degrees), then mains pressure water is released. That would be 7.5 bar in my house, according to the dial. No idea if that is accurate.
> 
> Thanks, new feature for me to play with!!


If your mains water pressure is 7.6 bar, I would strongly advise you to fit a proper pressure reducing valve (not a cheapie that doesn't properly reduce static pressure) to the feed line of your espresso machine, your looking for around 2.5 bar....*sort of right away really!*


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## jesperzac (Sep 2, 2015)

Hi Dave,

Thanks a lot for elaborating on this. I understand your post to the effect that under normal circumstances, I will not damage my Duetto by doing so (which is good seeing that I have done it for a year or so).

I think I will skip the un-plumbed pre-infusion for a period to test how the result is without it.







)


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## WEJ (Apr 11, 2013)

Hi Dave, Can you suggest/recommend a pressure reducing valve?

Apologies for the thread hijack!

Many thanks,

Wyn


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## DavecUK (Aug 6, 2013)

WEJ said:


> Hi Dave, Can you suggest/recommend a pressure reducing valve?
> 
> Apologies for the thread hijack!
> 
> ...


It's difficult, but if it were me I would choose a reasonable quality brand...you want something that truly creates a constant outlet pressure regardless of inlet pressure. Wour machine will also appreciate it with better pressure management of the shot.

http://www.screwfix.com/p/honeywell-pressure-reducing-valve-with-gauge-15mm/69396#product_additional_details_container


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## WEJ (Apr 11, 2013)

Great, many thanks Dave.

Wyn


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## Prusev71 (Mar 19, 2015)

DavecUK said:


> 1. There is some basis to the comment by Clive Coffee, but not quite for the reasons they think! If a machine is *unplumbed* and is a traditional HX machine, then allowing water to dribble from the group will at worst empty the HX unit within the boiler...but hey that's no biggie. It can't damage the brew group or anything else, however the machine will not work in the way intended/designed, especially with respect to temperature management.
> 
> However, and this is important....any machine with a single boiler or a *dual boiler* does not usually have a method to detect low water in the brew boiler, these type of machines have no autofill circuit/detection within these boilers. There is the potential for damage if enough water is run out. Admittedly this is unlikely in a preinfusion scenario, unless you forgot and left the machine in that state! You could of course get some air/headspace in the boiler of these machines, it also depends on the specific design of solenoid valve used and whether any air can get back from the group. These are not generally designed for situations, except in machines I have had some involvment with. Even then it's undesirable. e.g. the Expobar Dual boiler machine has definitely not been designed with this scenario in mind, The Rocket Dual boiler has some limited tolerance (very limited though) to this due to it's design. Duetto, Verona, Vesuvius, will all stand up to this much better, because of their design.
> 
> ...


Dear All,

The matter you had discussed is very interesting to a newby like me. :waiting:Would you, please, share your opinion on the following. Is it correct to generalise in equal other conditions, which combination will give the best result inb the cup:

1. rotary pump plus water tank;

2. rotary pump plus mains connection redused to 2-3 bars;

3. vibration pump plus water tank.

BTW, would you agree with the BB Rocket Cellini Evoluzione reviewer statement that the "value/price" ratio of Rocket is better than those of Alex Duetto? I read that till 2010 the quality of Alex was poor and after that they increased it.

Did somebody make the difference in the taste in a row shots between Expobar Brewtus IV and Alex Duetto III? The BB UK reviewer stated that Expobar Brewrus III has little compromise in taste regarding Alex Duetto.

Thanks and regards,

Petar


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## mrsimba (Mar 17, 2014)

I'm hoping number 4 is going to give the best taste in the cup!

4. Lever + mains connection


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## DavecUK (Aug 6, 2013)

Prusev71;355574
1. said:


> BTW, would you agree with the BB Rocket Cellini Evoluzione reviewer statement that the "value/price" ratio of Rocket is better than those of Alex Duetto? I read that till 2010 the quality of Alex was poor and after that they increased it.
> 
> 2. Did somebody make the difference in the taste in a row shots between Expobar Brewtus IV and Alex Duetto III? The BB UK reviewer stated that Expobar Brewrus III has little compromise in taste regarding Alex Duetto.
> 
> ...


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## Prusev71 (Mar 19, 2015)

DavecUK said:


> 1. No I wouldn't agree with that statement (I'm hoping I didn't make it for the dual boiler machines?) ...edit, Hopefully I clarified this with respect to *specifically *HX machines....as I hate being Misquoted, below is exactly what I said in the review for the machines at the time (May 2010).
> 
> *
> Bella Barista will hate me saying this: the overall quality and components used in the Giotto Evoluzione is so good, it represents better value for money than the Izzo Alex MKII dual water. *
> ...


Dear Dave,

Sorry for missquotation! It was not intentionally! The word "hate" means that I had offended you. Sorry about it also! For me the meaning in the same. Your statement was that Gioto Evoluzione (v1 during that time) has been bilt with better materials than Alex Duetto (double. BTW, it is in line with what I read that till 2010 Izzo quality level has been bellow the current one.

Had you make blind cup testing between these brands - Alex, Rocket, Expobar?

I read a post in HB from 22.09.2013 where Dan Kehn & co had made blind testing between Alex Duetto IV and LM GS3 where Alex performed pretty well.



DavecUK said:


> 1. No I wouldn't agree with that statement (I'm hoping I didn't make it for the dual boiler machines?) ...edit, Hopefully I clarified this with respect to *specifically *HX machines....as I hate being Misquoted, below is exactly what I said in the review for the machines at the time (May 2010).
> 
> *
> Bella Barista will hate me saying this: the overall quality and components used in the Giotto Evoluzione is so good, it represents better value for money than the Izzo Alex MKII dual water. *
> ...


Dear Dave,

Sorry for missquotation! It was not intentionally! The word "hate" means that I had offended you. Sorry about it also! For me the meaning in the same. Your statement was that Gioto Evoluzione (v1 during that time) has been bilt with better materials than Alex Duetto (double. BTW, it is in line with what I read that till 2010 Izzo quality level has been bellow the current one


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## Prusev71 (Mar 19, 2015)

Dear Member,

What do you think about this opinion for pre-infusion. Being a Ph.D. on Physics and Electronc Engineer, I am fully agree with the author:

*E61 Preinfusion confusion - **by Dave Corby*

I see a lot of discussion on forums about pre-infusion on the E61 and the E61 middle position. This tends to come up on a regular basis and usually receives conflicting and confusing responses. I think it's time to examine this area a little and try to clear up some of the confusion.

Firstly, the E61 has built in pre-infusion, in the lower chamber of the group there is a preinfusion chamber and while this fills the pressure to the coffee puck is lower measured with a pressure measuring portafilter. This chamber is sealed with a weak spring seal that lets by at around 4 bar. The chamber fills very quickly a matter of a few seconds for a rotary and a little longer for a vibration pump. The idea of this is to prevent the shock of 9 bar water hitting the coffee puck in the portafilter and allow a more gradual ramp up of pressure. this is by design, this is correct and it works well.

The "Middle Position" preinfusion is really opening the top brew valve before the pump runs and wetting the puck.

§ line pressure water in the case of a plumbed in machine (should be 2 bar if you have regulated pressure correctly)

§ * or passive flow from the hot water expanding out of the HX unit in a non plumbed machine (hot dribble). I personally don't believe either is correct because of the way that these machines function.

Then there is the passive dribble from the twin boilers brew boiler (not the same problem as in the first 2 scenarios, but still not correct). *This puck wetting has advocates, I am not one of them and have not tasted any significant shot difference after setting up various machines to do this "puck wetting".*

The middle position on an E61 will only let line pressure water through when the top brew valve is open and the pump is not engaged&#8230;.this is purely a function of how far the micro-switch that turns on the pump protrudes through the front fascia, as this directly impacts how soon the lever cam is able to actuate it during movement of the lever. If the micro-switch pokes out a long way, then the pump will engage slightly before the top brew valve opens, hence . Or the reverse with the switch set too far in and the group opens before the pump engages, then it's possible to carefully raise the lever to a specific point where line pressure water flows through the group but the pump does not run. A typical brew switch is shown below, both the front and the back (inside the case), adjustment is via the two nuts either side of the front fascia panel.



















*In the Goldilocks scenario&#8230;."it's just right" when the pump runs almost exactly as the group opens. This is how most manufacturers set it up and by design they are not expecting anyone to do any passive "puck wetting", which is why it's never covered in the instructions.*

The E61 that may be the exception to the rule with respect of built in pre-infusion are some automatic solenoid operated E61's which sacrifice the preinfusion chamber for the electrically operated group exhaust solenoid and it's often a reason why some of the semi automatic machines might be best avoided. Some other non E61 machines simulate the E61 preinfusion using a separate expansion chamber in the brew circuit e.g. La Spaziale Vivaldi S1 and Mini Vivaldi

Thank you for your time,

Petar


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## Prusev71 (Mar 19, 2015)

And sory for the stupid question, but there is a discrepancy in the Alex Duetto marketing compaign?! Everywhwre in the forums the brew bolier is advertised as 800 ml, but on their site (redirected by BB UK) it is written that it is 580 ml - just as Rocket R58. If this is the case, there is no differentiator among Alex competitors:

https://www.bellabarista.co.uk/pdf/ALEXDUETTOIII-MKIV.PDF

What do you think about it?


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## DavecUK (Aug 6, 2013)

Brew boiler is 800ml unless they changed my original design specification...which I doubt.

The Izzo Alex MKII dual water is a HX machine and NOT a Duetto (dual boiler)...I was comparing build quality with this machine and the Rocket HX...not the Duetto. Also value for money is a generic term as it's not necessarily comparing just build quality.

Hate is just a turn of phrase...I wasn't offended.


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## Prusev71 (Mar 19, 2015)

DavecUK said:


> Brew boiler is 800ml unless they changed my original design specification...which I doubt.
> 
> The Izzo Alex MKII dual water is a HX machine and NOT a Duetto (dual boiler)...I was comparing build quality with this machine and the Rocket HX...not the Duetto. Also value for money is a generic term as it's not necessarily comparing just build quality.
> 
> Hate is just a turn of phrase...I wasn't offended.


Thank you Dave! And please, forgive the errors of a newby whose mother tongue is not English ...

So, from your view pint can (which is top important for me) we make the following assertion: the espresso aroma effect produced by vibration pump + watter tank due to slow rump up of the pump to 9 bars is similar (if not equal) to those caused by rotation pump + water mains?

P.S. I could not find a way to attach MS Word files in a thread. Please, help if I am wrong.


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## Prusev71 (Mar 19, 2015)

BTW, this is written in the Alex documentation:

Volume

boiler group coffee 0,58 litre

Volume

boiler for steam 1,8 litre

Weight 32 kg - 70,55 lbs

It is not written by BB document. Another thing - the water tank. In the same document it is written 3 litres, while at different online stores I saw 2.4 lt, 2.6 lt, etc. Why there are such discrepancies?


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## Prusev71 (Mar 19, 2015)

Dylan said:


> As WEJ mentions, the 'half way' point on an e61 lever will give you 'preinfusion' at whatever your main pressure is if you are plumbed in.
> 
> A tank fed e61 still has preinfusion but of a different type. As the vibratory pump activates and fills the lines and e61 with pressurised water the pressure ramps up to the set pressure, giving you a 'preinfusion'. As far as I know when you have a mains fed machine with a rotary pump this pressure build up is much quicker with the group fully open.
> 
> ...


Thank you, Dylan for the useful links! From HB threads I learned that forgiveness factor depends much more from the group head (head space above and below the dispersion screen) than from the type of pump). Do you have some newer information sources on the matter since these are from 2007?


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## Nobodysdriving (Jul 4, 2015)

DavecUK said:


> It's difficult, but if it were me I would choose a reasonable quality brand...you want something that truly creates a constant outlet pressure regardless of inlet pressure. Wour machine will also appreciate it with better pressure management of the shot.
> 
> http://www.screwfix.com/p/honeywell-pressure-reducing-valve-with-gauge-15mm/69396#product_additional_details_container


Hi DavecUK, is this honeywell pressure reducing valve you're linking to ready to be connected? what I mean is would I need any adaptors at all? (I have the Brita Purity C150 Quell ST feeding my Izzo, connections are 15mm)


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## El carajillo (Mar 16, 2013)

The Honeywell P R V is 15 mm compression on both ends. You say your supply from filter is 15 mm therefore it will be a straight forward fit. If you have plastic pipe do not forget to fit the "inserts" in the cut ends of the pipe. These support the pipe wall to accept compression fittings


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## Nobodysdriving (Jul 4, 2015)

El carajillo said:


> The Honeywell P R V is 15 mm compression on both ends. You say your supply from filter is 15 mm therefore it will be a straight forward fit. If you have plastic pipe do not forget to fit the "inserts" in the cut ends of the pipe. These support the pipe wall to accept compression fittings


thank you El carajillo

I have got the gauge now but still don't know how to fit it!

first of all it is impossible for me to get to the machine connection with a straight spanner as one of the white water-waste pipe on the right is in the way (not the one you can see in this photo then goes upwards and it is very close and I cannot get my hand in with the spanner to undo the flexible pipe going to water filter)

then even if I managed to undo the water filter flexible pipe (the silver one going upwards) I still don't know how to as the pressure reducing valve has a male connection and the water pipe also is a male connection so how does that one work out???


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## mrsimba (Mar 17, 2014)

From the photo think I'd be looking to remove the washing machine fitting and put another T in onto the existing T then you can connect the washing machine back 'in line' and take a line off the 'new' T for the PRV - if your fitting filtration you need to fit that first and then put the PRV in after that last in the line to the machine









I feel feel your pain tho my existing plumbing was very similar and ended up taking a feed off the supply to the combi boiler which whilst requiring a few more meters of pipe was a very simple install requiring only a few fittings

* also a straight spanner is prob not going to get into those fittings you really need something like this http://www.ebay.co.uk/itm/Knipex-86-03-250-Pliers-Wrenches-Pliers-Wrench-In-A-Single-Tool-250mm-/381038670285?hash=item58b7acb1cd:g:1K8AAOSw3ydVphtq

That'll make easy work of the job!


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## mrsimba (Mar 17, 2014)

roughest sketch ever but along these lines...










obviously with shut off valves fitted before the washing machine & filter/PRV !


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## Nobodysdriving (Jul 4, 2015)

mrsimba said:


> roughest sketch ever but along these lines...


thank you mrsimba to go to such length to help me









however that is not a washing machine, that IS the line to the coffee machine (well the brita in line filter which feeds the washing machine







)

My main worry/gripe is how do I fit the PRV when it is a 'male' connection onto the existing pipe which is also a 'male' connection?


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## mrsimba (Mar 17, 2014)

A brass socket will allow you to attach male - male fittings together -

http://www.toolstation.com/m/part.html?p=24305

I'd probably take your existing T out and replace it something like this -

http://m.ebay.com/itm/121449478656?_mwBanner=1

and then work your plumbing forward from there!


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## Dylan (Dec 5, 2011)

If its a pain to add fittings to that location, you could buy a 1/2" to 1/2" short flexible hose, attach this to where you coffee machine is currently attached, then add a T between this new hose and your coffee machine one.


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## jeebsy (May 5, 2013)

Strip it back and get pushfit on there


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## mrsimba (Mar 17, 2014)

Nobodysdriving said:


> My main worry/gripe is how do I fit the PRV when it is a 'male' connection onto the existing pipe which is also a 'male' connection?


With mine connecting the male-male I just used a very short length of copper pipe and a compression fitting so it went - 90' push fit from filter - copper pipe compression - PRV - copper pipe compression - straight shut valve - coffee machine

So you'd be looking like this -


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