# Giotto Plus v3 - 123c on PID very limited flash boil, poor rebound and sour shots



## JackBlackmore (Nov 1, 2015)

Morning all,

I'm slowly diagnosing my sour shot issue and can fairly confidently point my finger at brew temperature. I'm using Clifton Coffee EQ (http://www.cliftoncoffee.co.uk/shop/eq-seasonal-espresso-blend-v-9/) which is a fairly light roast but it's grinding a dream, fairly dry fluffy grinds and super easy and nice steady even extraction using a naked portafilter. I've been using 18g grounds (I have a Ceado E7 grinder) and experimented from 1:1.5 to 1:2.5 brew ratios in around 30 seconds extraction and the shots are still coming out different styles of sour i.e. strong and sour to thin and sour.

Given that all other variables seem to be under control the only thing I can put it down to is temperature. To start with I had to the PID set to 119 with a 40 minute warm up but now I'm at 123c (around 1.35 bar on the steam boiler) with an hour warm up, I leave the portafilter in the grouphead and everything is super hot to touch by the time I'm coming to pull my shots in the morning.

I'm not doing more than 80ml cooling flush to remove the flash boil then weighing / grinding beans, filling the portafilter, a small amount of WDT and tamp which all probably takes in the realm of 30/40 seconds then pulling my shot. The process for the second shot is the same with the added knocking out and wiping the portafilter (dry cloth) so maybe a minute. The shots have definitely got better since I've upped the PID to 123 but they're still on the sour side and from what I've read elsewhere I should be able to pull light roasts at 119 however they were tooth enamel stripping sour. I've tried a few different beans and had the same / very similar results.

Sorry for the length of the post but I wanted to cover to give as much info as possible as I'm at a bit of a loss. From videos I've seen online the length of the cooling flush seems very short for the boiler temp being so high? Any suggestions on what I can try next other than getting the professionals in? *cough* @coffeechap *cough*


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## coffeechap (Apr 5, 2012)

Have you tried measuring the brew water temp?


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## JackBlackmore (Nov 1, 2015)

I'll try over the weekend but that thing really hisses like hell. I haven't got a digital thermometer and the glass one I've got is super slow so ill pick one up over the weekend.

Realistically I've got no benchmark to compare anything against so I'll try and post some videos over the weekend because it's probably a much better indication rather than my general lost waffle


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## JackBlackmore (Nov 1, 2015)

I don't want to get too ahead of myself but I think I've resolved it. I descaled the HX part of the machine with Citric Acid yesterday, checked the thermosyphon restrictor for gunk (there wasn't any) and bled the mushroom and so far so good. Haven't had a sour shot with the PID set at 121.

I'll try pulling back to back shots tomorrow morning and see how it goes but the ones I've had since then haven't had a trace of sourness! Can only assume something somewhere was a bit scaled / blocked and was stopping the grouphead from heating properly.


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