Author Topic: Gaggia Preheat  (Read 2866 times)

Offline D4F

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Gaggia Preheat
« on: February 07, 2014, 04:59:00 PM »
Most Gaggia preheat involves making a copper tubing coil around the boiler and then plumbing it in between the pump and OPV.  The coil is passively preheated as the boiler heats and then the preheated water can enter the boiler instead of cool and help to stabilize the intrashot drop, and ideally help to stabilize for a second pull.

That is a great idea until you realize that the pump flows about 260 ml/minute, or about 125 ml/25 second shot, and the tubing holds about 60 ml.  A bit more tubing can be used, but still the problem; the heated water ends up in the tank and some in the boiler, but no help for a quick second pull.

The KitchenAid Proline has the OPV separate from the boiler and allows the OPV to be plumbed in before the coil and therefore cool water is diverted back to the tank and the tubing still has heated water.  Pizzaman has done this and posted on GUG.

In theory, the OPV could be removed from the boiler and a non-OPV inlet substituted.  A second inlet could be mated to the OPV and then a freestanding OPV is possible.  I have not verified this, but is seems like it would work from the old math principle, two things equal to a third thing are equal to each other, morphed into two things that mate to a third thing mate to each other.  Ideally that could have a standoff mount.

http://www.wholelattelove.com/Gaggia/gaggia-b0111.cfm

Hopefully this thread will lead to a discussion about preheat coils.  A “How To” would be nice with exact tubing, proper bending and mounting methods, and fittings.

Offline SusanJoM

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Re: Gaggia Preheat
« Reply #1 on: February 07, 2014, 05:08:51 PM »
Here are a picture and a graph couple of graphs created by a member who did the copper tubing mod to his Proteo Romanza
“Not everything that can be counted counts, and not everything that counts can be counted.”
Albert Einstein

Offline pizzaman383

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Re: Gaggia Preheat
« Reply #2 on: February 07, 2014, 06:26:48 PM »
I'll try to get some pictures up in the next few days but I'll start with some descriptions.

I wanted to maximize the heat transfer to the preheat coil so that it would be as near in temperature to the water in the boiler.  That means two things - get the tubing as close to the boiler as possible and filling in gaps with heat-transferring material.

Because of the fittings I had on the KA I used 6mm copper tubing with 1mm thick walls.  This is harder to bend but doesn't pinch as easily so I could form it closer to the boiler.  I started at the bottom edge of the boiler, wrapped the coil around one side, made as tight a corner as possible, then did the same all the way around to get the first wrap.  I then continued this all the way up.  Be careful as you put it around the thermostat; I broke one by putting too much pressure on it.  Once I got the tubing wrapped around the sides I looped up and over the top of the boiler then down to the water inlet (mine is similar to the picture above but not exactly the same).

I used tightly-folded aluminum foil to fill gaps so that as much as possible of the coil is touching the boiler or a (mostly solid) block of aluminum foil.  This contact transfers heat MUCH faster than air gap.  It's crucial if you want a fast recovery between shots.  It takes some fiddling to get the aluminum placed in all the spots you can while still keeping all of them nice and tight.  I ended up wedging, pushing, etc. a fair bit but it all worked out.

Both my brother and I have actually installed the preheat coils three different times.  We learned what worked and didn't work each time so don't be surprised if it takes a couple tries to get it right.

Offline D4F

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Re: Gaggia Preheat
« Reply #3 on: February 07, 2014, 06:41:34 PM »
Where do you get that tubing?

Fittings necessary?

So you just bend the tubing as you come to a corner, no tools?  Just bend it by wrapping?  Can you slide it on and off, can it be made on one and then put on another?

Offline pizzaman383

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Re: Gaggia Preheat
« Reply #4 on: February 07, 2014, 06:53:42 PM »
Since I have the Vibiemme and I had done some internal replumbing on it I purchased european fittings called British Standard Pipe (BSP) fittings.  They're not compatible with 1/4" US copper tubing and they're not compatible with US standard pipe fittings.  I purchased them at Orphan Espresso, espressoparts.com, and cafeparts.com.  These fittings use solder-on mushroom fittings on the end of the tubing.  They work but they are a hassle due to the soldering.

I'll see if my brother will post the fittings he used.

Offline D4F

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Re: Gaggia Preheat
« Reply #5 on: February 07, 2014, 06:55:47 PM »
Did you try 1/4" and fill with salt?

http://www.instructables.com/id/How-to-Bend-Copper-Pipe-and-Tubing-without-Crushin/

Did this with a friend on a different application and it could work??

Heat anneal?
« Last Edit: February 07, 2014, 06:58:51 PM by D4F »

Offline pizzaman383

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Re: Gaggia Preheat
« Reply #6 on: February 08, 2014, 08:42:14 AM »
Filling with salt is a great idea!  I think that would make using standard 1/4" tubing very easy.  You could really bend it right where you want it.

Offline pizzaman383

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Re: Gaggia Preheat
« Reply #7 on: February 09, 2014, 10:38:45 AM »
From my brother.  He's got a Gaggia Coffee that he upgraded to the solenoid group.
Quote
The list of fittings is listed below. Note that I used elbows to make the routing easier since the teflon tubing does not easily bend without kinking. I bought 18" or so of teflon tubing.

Here's a description of how things are routed:

The teflon tubing comes out of the 90 degree pump fitting, goes across the machine and down to the OPV which sits on the bottom right of the machine. The teflon tubing to OPV connections are using 1/8 BPP fittings and compression bicones and nuts from orphan espresso. I wrapped the OPV with rubber weather stripping so that vibrations don't pass to the machine case. Out of the OPV, the teflon comes back up and across the machine to near the pump output. (that way I can run it with or without the preheat fairly easily.) There is one cole-parmer compression fitting, a 90 degree elbow, and another cole-parmer compression fitting to transition to the 1/4 OD flexible copper preheat. The preheat coil wraps from the bottom of the boiler to the top, counter clockwise, ending at the top back right of the boiler. At the end of the final preheat coil, another cole-parmer compression fitting, 90 degree elbow, and another cole-parmer compression fitting to transition back from 1/4 OD copper to teflon. There's a very short (around an inch) teflon tube down to the gaggia inlet fitting. since I started with a Gaggia Coffee, not a Gaggia Classic, mine came with the inlet that did NOT have a built in OPV.

out of the pump to teflon tubing (6mm OD x 4mm ID):
http://www.espressoparts.com/V_549

teflon tubing to 1/8 BPP:
http://www.orphanespresso.com/Bicone-NUT-Brass-Fitting-14-for-6mm-Tubing_p_4865.html

4859 Bicone 6mm Brass Fitting from orphan espresso

1/8 BPP fittings to OPV:
assorted elbows and tees from Orphan Espresso
http://www.orphanespresso.com/search.asp?keyword=1%2F8&search=Find

OPV:
https://www.chriscoffee.com/SearchResults.asp?Search=ev321&Submit=Search

1/8 BPP fittings to 6mm teflon:
same bicone & nut as above

6mm OD teflon tubing to 1/4 NPT:
http://www.coleparmer.com/Product/Compression_To_Thread_Adapter_Stainless_Steel_6mm_OD_Tubing_X_1_4_NPT_M/EW-31528-02

1/4 NPT 90 elbow

1/4 NPT to 1/4 OD flexible copper (preheat coil):
http://www.coleparmer.com/Product/Compression_Fitting_Male_Pipe_Adapter_Straight_316_SS_1_4_OD_x_1_4_NPT/EW-31406-35

preheat coil out end:
http://www.coleparmer.com/Product/Compression_Fitting_Male_Pipe_Adapter_Straight_316_SS_1_4_OD_x_1_4_NPT/EW-31406-35

1/4 NPT 90 elbow

1/4 NPT to 6mm OD teflon tubing:
http://www.coleparmer.com/Product/Compression_To_Thread_Adapter_Stainless_Steel_6mm_OD_Tubing_X_1_4_NPT_M/EW-31528-02

6mm OD teflon to boiler inlet:
http://www.shop.partsguru.com/B-0111-Gaggia-water-inlet-fittingO-ringLube-B-0111.htm



« Last Edit: February 09, 2014, 10:43:07 AM by pizzaman383 »

Offline D4F

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Re: Gaggia Preheat
« Reply #8 on: February 09, 2014, 01:49:50 PM »
I looked back at a few links and found several pictures that may help.  Note that most of these are not exactly what is desired in that the OEM OPV position was retained, coming after the copper wrap and diverting water back to the tank.  You need to factor in an OPV move with the CrisCoffee OPV or move the Gaggia one and back it with the inlet.  The photos are helpful and you can see fittings and an added gauge.

The tubing is 1/4" copper and the fittings are "universal." They are brass, and designed for either 1/4" copper or plastic tubing.  You can usually find them up at hardware stores, Home Depot or Lowes.  Some are listed with internet sources.

http://coffeegeek.com/forums/espresso/machines/214679?LastView=1391893238&Page=1
 
http://coffeegeek.com/forums/espresso/machinemods/436367
 
http://coffeegeek.com/forums/espresso/machinemods/390284
 
http://randytsuchpreheater.blogspot.com/2009/11/gaggia-preheater-construction-rev-1.html
 
http://coffeegeek.com/forums/espresso/machinemods/566170

Offline pizzaman383

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Re: Gaggia Preheat
« Reply #9 on: February 09, 2014, 07:31:02 PM »
Here are some pics of my brother's gaggia with the preheat coil.  The coils are covered with aluminum duct tape to keep the heat in.





« Last Edit: February 10, 2014, 11:21:42 AM by JR »

Offline D4F

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Re: Gaggia Preheat
« Reply #10 on: February 09, 2014, 08:33:49 PM »
Great photos and supply list, thanks.  Your thoughts on stainless versus brass fittings?

Offline pizzaman383

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Re: Gaggia Preheat
« Reply #11 on: February 09, 2014, 09:30:28 PM »
Eric used the stainless fittings because they were high-pressure, pneumatic fittings that would bite the plastic tubing better not because they were stainless.

Offline The Big L

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Re: Gaggia Preheat
« Reply #12 on: February 09, 2014, 09:47:11 PM »
Cool, thanks for the photos, and for all the interesting discussion on this topic.

Every time I see a picture of that boiler from the top, I start thinking about whether there's any way to use the steam outlet on the top to both insert a temperature probe and preserve steaming capability.  It hasn't come to me just yet.  Have you two already covered that topic in one of your detailed conversations?

Offline D4F

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Re: Gaggia Preheat
« Reply #13 on: February 09, 2014, 09:57:09 PM »
That is a problem on Gaggia, not on Proline with double boiler.  One of the threads that I listed above is for Daduck on CG and he custom made the probe insert and still gave up the steam valve. 

http://coffeegeek.com/forums/espresso/machines/214679?LastView=1391893238&Page=2

You get to design the probe/valve and make it, if you want both :)

That is the reason that I would still use the PID with sensor in the OEM position but switch from PID to alarm to add heat intrashot, if intrashot or brew heat is still needed or desired.

Offline The Big L

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Re: Gaggia Preheat
« Reply #14 on: February 10, 2014, 10:54:35 AM »
D4F, your ability to quickly recall the appropriate thread amongst the many threads here and on CG is both admirable and highly appreciated!  I suppose when you've been an active participant in all those threads it's a bit easier, but for me I lose track of them very quickly.  I've always been able to count on you to point me to the relevant resource.  Thanks!   :)

Yes, I meant the Classic boiler vs the KA on this page -- but they look pretty similar to me.  Then again, I don't have the schematics memorized like some people probably do.  *ahem*    ;)

 

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