# Pre infusion mod on a classic ?



## Asgross (Jun 14, 2015)

I am thinking of trying to add pre infusion to my ( mr shades) pid Classic

Has anyone added this and have an opinion as to whether or not it's worth doing ?

I've read online the starting point is to change the pump to a 65w cp3a

Apparently invensys no longer make the brown bodied cp3a pump









And wondered if anyone thinks this will work ?

are they all pretty much comparable ?

And where has anyone successfully attached the wires for the dimmer switch?

thanks

alan


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## MrShades (Jul 29, 2009)

I've done this - really needs a pressure gauge in-line with the pump to boiler piping so that you can actually use the dimmer also.

Dimmer just connects directly to the pump - either cable - doesn't make a difference (at least I don't think it does, or did when I tried it).

Technically I believe the Ulka pump just doesn't work well with dimmed voltages with any dimmer. When I swapped to an Invensys it was a revelation - hugely different behaviour.

Try any Invensys pump - but then finding a dimmer that works well is a real challenge.

I imported a couple of the 600W Leviton dimmers that the Yanks use - and even they didn't work on the Ulka.

I have been using a lamp "floor dimmer" with a slider - 600W I think - and it gives full control from 0 bar to 9 - lovely!

I use it a lot and would recommend it - but factor a pressure gauge into the install as well.


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## Rhys (Dec 21, 2014)

Stick a pressure gauge on a portafilter, do the opv (if you haven't already), click on the brew switch and turn the steam valve open until the gauge reads approx 1 bar. Mark on the steam valve and body where the valve is open to.

Now all you have to do is when you go to pull a shot, open the steam valve to where you've marked it and turn on the brew switch. You will then get pre-infusion pressure at the brew head. After 6 to 10 seconds, slowly turn it off to get full pressure at the brew head. You will need to put a cup or jug under the steam wand btw.


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## martinierius (Sep 28, 2014)

Rhys said:


> Stick a pressure gauge on a portafilter, do the opv (if you haven't already), click on the brew switch and turn the steam valve open until the gauge reads approx 1 bar. Mark on the steam valve and body where the valve is open to.
> 
> Now all you have to do is when you go to pull a shot, open the steam valve to where you've marked it and turn on the brew switch. You will then get pre-infusion pressure at the brew head. After 6 to 10 seconds, slowly turn it off to get full pressure at the brew head. You will need to put a cup or jug under the steam wand btw.


That's certainly worth a try but wouldn't you be leaching too much hot water from an already small boiler?


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## Rhys (Dec 21, 2014)

martinierius said:


> That's certainly worth a try but wouldn't you be leaching too much hot water from an already small boiler?


Probably, pidded may help but since it isn't built to pre infuse it's all a compromise really.


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## Asgross (Jun 14, 2015)

I really appreciate everyone's suggestions

I've got a dimmer 500w floor switch coming from Amazon and plan to order a new cp3a 65w Invensys water pump

Trying to keep my mods to a minimum ( because I completely sh*t at diy)

Fitting the pressure gauge to the boiler and wall of classic is probably beyond me !

Instead After fitting the dimmer and the water pump

Could I just attach a gauge to the portafilter and mark along the dimmer switch representing incremental increases in the pressure to readings initially off the gauge ?


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## Rhys (Dec 21, 2014)

Did this vid when I was mucking about with my grinder. You can hear it change tone when I close the steam wand to put it up to full pressure. Not much water comes out of the steam wand tbh.


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## Asgross (Jun 14, 2015)

Did you open the steam valve prior to switching on brew ?

How long do you leave the steam open for ?


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## Rhys (Dec 21, 2014)

Opened it up just before hitting the brew switch (its how you get hot water out of a classic btw) then closed it slowly after about 6 seconds. You can hear the pump start working harder as it builds the pressure up. No idea how much difference it makes in a Classic tbh, I just perceived it to be better as it's pushing the best out of a machine that it's not actually designed to do. It will probably help regarding channelling and fracturing, as the puck is give time to soak and expand instead of just being hit with 9 bar of (pulsed, vibe pump) pressure. I keep meaning to get mine out again to give it a go.


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## Asgross (Jun 14, 2015)

Thanks, before I try and and fit the dimmer switch and new pump next week, I'll try this with a pressure gauge and then with coffee


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