# Heat surfing with naked pf



## igm45 (Mar 5, 2017)

Just a quick one please,

I have a hx machine. I read somewhere that before pulling a shot you need to cool flush the machine. I read that to do this you just let it run until you get a steady stream of water.

That works fine with a spouted pf, how do you do it with a naked pf? I found that even with near to perfect extraction I was getting sour shots, I cool flushed for shorter and relieved this problem.

Is there an accurate way of knowing how long to do it for with a naked pf?

Cheers


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## DavecUK (Aug 6, 2013)

igm45 said:


> Just a quick one please,
> 
> I have a hx machine. I read somewhere that before pulling a shot you need to cool flush the machine. I read that to do this you just let it run until you get a steady stream of water.
> 
> ...


Cooling flush is best done without the pf in the machine.


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## igm45 (Mar 5, 2017)

Thank you. Whats should I be looking for to know when it is suitably cooled?


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## kennyboy993 (Jan 23, 2017)

If you have e61 machine do it until the hissing stops and then pull the shot between 30 and 120 seconds after.

This is a general process for a modern e61 hx e.g. Rocket, ecm etc.

If u want to go geeky you can get group head thermometer. I'm selling mine though haven't put it up yet


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## igm45 (Mar 5, 2017)

kennyboy993 said:


> If you have e61 machine do it until the hissing stops and then pull the shot between 30 and 120 seconds after.
> 
> This is a general process for a modern e61 hx e.g. Rocket, ecm etc.
> 
> If u want to go geeky you can get group head thermometer. I'm selling mine though haven't put it up yet


Thank you,

My current bean is a light roast SO which seems to be susceptible to tipping from acidic to sour.

The cooling flush has more impact on this than I would have thought. I seem to prefer the flavour if I flush for shorter than recommended.

Might experiment with different brew ratios and see if I can dial back the sourness.


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## kennyboy993 (Jan 23, 2017)

Yes in my experience you have to be precise with the cooling flush for lighter roasted SO beans.

Or it might be how that bean is meant to taste.

One way to confirm is to flush and then wait a good 3 mins or so - this should ensure a brew temp above whats recommended. At least this way you can rule out brew temp with this bean of its still sour


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