# Little Gem low flow rate through group head



## Aidy (Jul 8, 2015)

Hi,

I've a little gem, and the flow rate through the group head seems very slow.

Both the hot water tap and the steam wand seem fine, so I'm kinda suspecting it's not a scale problem (and we're in a soft water area anyway).

It's been backflushed fairly regularly, although perhaps not as often as ideal, and I've taken the shower screen and the dispersion plate off and given them a good soak in puly caff - still doesn't seem right.

I've had a quote for a front end service from Fracino, but it seems a little spendy - Anyone have any suggestions?


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## 4085 (Nov 23, 2012)

have you measured the flow rate? Pour for 30 seconds into an empty cup on scales and tell us the weight


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## Aidy (Jul 8, 2015)

Getting about 65g of water through the group head 30s after pressing the button. There's maybe a second or two of delay before water starts emerging from the group head.


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## espressotechno (Apr 11, 2011)

Try backflushing with some descaler: Even in a soft water area, scale can slowly build up over several years.

Also, remove the big nut on top of the the grouphead & check for scaling up of the the small group jet: To clear it, just pour in some neat descaler solution...


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## Aidy (Jul 8, 2015)

Cheers - don't have a thin enough spanner to get at the top nut without having to take apart more of the machine than I have time for right now.

I'll try descaler in a bit - what kind of flow rate should I be getting?


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## 4085 (Nov 23, 2012)

I will measure mine this morning, but I think you are not far away. I extract around 30 gm of coffee in about 25 to 30 seconds but that is through a puck. the flow through the group will always be slower than through the water tap. Have you tried weighing out say 15 gm of coffee onto your pf, taring scales and putting a cup under t and measured how much coffee you extract in a given time?


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## Aidy (Jul 8, 2015)

Too dependent on grind, surely?


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## 4085 (Nov 23, 2012)

no pf attached, 30 seconds gave 32 gm of water. my machine ha s a rotary pump and is new


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## Aidy (Jul 8, 2015)

Hm - thanks.

I'm definitely getting longer shot times than I ought to given my grind size - I'll have to get a pressure gauge on it.


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## MWJB (Feb 28, 2012)

Aidy said:


> Hm - thanks.
> 
> I'm definitely getting longer shot times than I ought to given my grind size - I'll have to get a pressure gauge on it.


Any info on any of these aspects?


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## 4085 (Nov 23, 2012)

You are talking about two different things. You initially said you felt the amount of water passing through the group without resistance, was too little when compared to your water arm. You are right. the grind will dictate how much water passes through the puck but that is not the same issue. The grind is tuning the shot which is why i said measure the water flow. You are getting twice the volume of water in 30 seconds that I am. Is there any other reason why you think your machine might be scaled up?


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## Aidy (Jul 8, 2015)

I came at this from my shot times being too slow.

Started looking at flow rate - which seemed low. I figured that an unrestricted flow (without the portafilter attached), should result in far more water passing through the group head than a double shot within 30s.


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## 4085 (Nov 23, 2012)

Aidy said:


> I came at this from my shot times being too slow.
> 
> Started looking at flow rate - which seemed low. I figured that an unrestricted flow (without the portafilter attached), should result in far more water passing through the group head than a double shot within 30s.


Why would unrestricted flow do that? the problem as I see it, is you are either putting the wrong amount of coffee into the pf. By that I mean the basket might be the standard basket with say a 14 gm capability. You might be putting in 16 or 12 which are both going to cause problems (are you weighing your grind out?). Secondly, if the grind is not correct, then the flow will be too little or too great. I measure output as +60% of the dry coffee weight. I am sure more knowledgeable folk will leap on me and tell me I need to convert my ways to % but I find it a toal pain in the arse working ratios and prefer to trust my mythos plus experience. Which ever way you do it, you will have a base line to measure against for your next set of adjustments.


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