Author Topic: Brass Shower Screen Holder- What should I expect on a practical level?  (Read 866 times)

Offline vindibona1

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Well... My Gaggia Classic has had one more mod today; a brass shower plate holder.  So far I've added the Silvia steam wand, IMS shower screen and a PID. Although very similar, I am now using my old Saeco Sirena portafilter instead of the Gaggia supplied one just because it feels and fills better.

I've just now received an installed a brass shower plate holder that I got from Espresso Parts (UK). The deciding factor in replacing it was how gross looking the original cast part looked, even after soaking in Cafiza.  The part was pretty cheap with shipping from the UK costing almost as much as the part.

FWIW, the brass holder weighs 216 gms compared to the original at 76 gms, almost 3x more mass.  It is logical that brass with more mass will transfer and hold heat better than the original.

So, what types of improvements, if any will I experience brewing or tasting?

TIA

Offline SusanJoM

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bragging rights  ;)
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Offline JojoS

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Cool! Does it take longer now to pre heat before you can pull a shot? You can now do detergent backflushing without removing the shower screen and plate holder.
« Last Edit: July 06, 2017, 10:50:12 PM by JojoS »

Offline SusanJoM

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You can now do detergent backflushing without removing the shower screen and plate holder.

JoJo, why is this different with the brass (heavy!!!) dispersion plate?  I'm missing something.
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Offline JojoS

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The detergent makes the aluminium plate holder dull with slimy gray residue.

Offline SusanJoM

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Ah ha....
I had no idea
Thanks.
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Offline AndyPanda

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I have one machine with the brass diffusion plate (shower screen holder :) )    And it does seem to make a difference (longer to heat up, slower to cool down).   But I don't know if it's necessary or not (i.e. would I spend the money again?).  The gaggia has the boiler directly above the dispersion plate so in a sense the plate is always being heated.   If you were to take a heated aluminum plate and a heated brass plate away from the heat (i.e. remove it from the Gaggia and set on your breadboard) the brass would take a lot longer to cool down and the aluminum would cool really quickly.   

And that is what makes it seem like it would be a really good idea to have the brass there -- so it will smooth out the temp rises and falls as the boiler heater kicks on and off -- and it does smooth it out (when it is rapidly changing up and down).  But in the real world you are trying to hold the Gaggia boiler stabilized at the perfect temp to start your shot (either with a PID or temp surfing routine) and the aluminum disk will be at the same temp that the brass disk is at when you start the shot.  So here's my question:as the boiler cools during your shot, is it helpful to have the brass which will give up the heat to the water more slowly (i.e gradually and slightly heat the cooling water passing thru it) Or is it better to have the aluminum which gives up its heat quickly? (i.e. heats the cooling water a bit more/faster but then is spent quickly).

I haven't done any experiments to say one way or the other - the above is just a thought experiment - but it seems to me that the aluminum disk giving up its heat to the water more quickly could be a good thing.  I don't really know.   

I do really like having the brass disk on mine :) but I can't say for sure if it's actually better.
« Last Edit: July 06, 2017, 08:42:30 PM by AndyPanda »

Offline vindibona1

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 Day 1.5 review...

The taste is different, but not better. I had worked my way past all the aftertastes with the aluminium plate.  I don't suspect it takes much longer to heat up, but I always give it at least 15 minutes, usually longer.

It seems to me that Andy Panda is right in that it is slower to give up the heat.  I'm thinking that may make the steam blip less practical.  Last shot yesterday and first shot today were consistent with each other.  So, in a bit I'll do a second pull with no steam blip to see what happens.

Update:
Pulled my second shot this morning, 1hr 40 minutes later (the machine stayed on for that time).  No steam blip and the taste was much smoother. Total brew time was 28 seconds.

The SV was 212F, but I noticed something surprising (I'm sure unrelated to the brass plate)...
When I would previously do the 3 second steam blip, the temp would rise from 212F to 221F, then fall to 208F during the pull.  However, without the blip, the temp only fell from 212 SV to 208 during the pull.  So my question is:  Why would the bottom end of the temp drop be the same for both methods? One would think that if the temp dropped 14 degrees with the same amount of water going into the boiler, you'd get a similar drop without the blip. But no- only 4 degree drop. Can someone please explain this to me?
« Last Edit: July 07, 2017, 10:47:16 AM by vindibona1 »

Offline D4F

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The temperature rise and fall are only at the sensor, not the water.  The blip raises the sensor temp, then it slowly diffuses heat into the water. 

The brass slowly looses heat to the water, so they both do similar.

Many non-PID users thought the brass plate helped, not so many PID users felt the same, from reading over the years. 

Offline vindibona1

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Many non-PID users thought the brass plate helped, not so many PID users felt the same, from reading over the years.

Sort of makes sense. I can see how the plate can smooth temps out a bit and can help a non-PID setup.  Its too early to tell, but at this moment I'm not seeing it helping. I can tell it's changed something so I don't feel I have a handle on it yet.   Luckily it's cheap and easy to swap out if I want to go back. .

Offline D4F

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I can't imagine a reason to switch back, certainly it doesn't harm. The original question was about practical benefit, and I just am not sure there is much bang for the buck just to change to brass..  If I needed a new one, I might opt for it.  When I see people ask about the brass screen holder and they don't already have a PID controller, my suggestion is to save the money.

I don't worry about the looks of the aluminum screen holder.  Find Jojos posts that shows his cleaning of the aluminum one, he does a great job, much better than I.

 

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