Mod: Adding hot water tap mixing valve (GS3-like). How?

[Louis]

Note: This is a cross-post with an existing thread on home-barista.com. I first thought this mod would apply to more machines than to the Vivaldi only, hence posting to HB, but I didn’t receive much technical/know-how answers and I didn’t get anymore answers after a few days. I thought I might get more feedback from here as I know many have tinkered with their Vivaldi over the years.

Since I've got the S1 Vivaldi, I found myself using the hot water tap a lot more than what I was expecting (can provide as much as 1L), even if I understand that a $2000 machine is not to be used as a $10 kettle, that I will get more scale as more water is going through the steam boiler, etc. Instant hot water is practical and this is simply hard to ignore.

The only issue I have is that the process is very inefficient: ~110°C water coming out as some 100°C hot water along with a lot of steam. The water is also too hot for our main use: green tea. We cool it off to 75-80°C (~175°F) by moving it through two different vessels before infusion. Wasted electricity to heat water; wasted electricity for the air-conditioner to cool down the excess heat.
[…]
I'm considering the addition of a hot water mixing valve to my Vivaldi to cool water to a more reasonable / practical temperature. The machine is plumbed-in and uses a solenoid valve for hot water. It uses plastic tubing, which seems ideal to do the mod (provided I can get the correct parts and fittings).
[…]
- Any idea where I could procure the correct parts?: connector to the S1 plastic tubing (out of steam boiler, back to hot water solenoid), Y between cool water mains and F-o-T pump inlet, inter-parts connections between the additional parts, check valves, Y, etc.
- Any worries to keep in mind to avoid a big mess (I'm already protected by an automatic mains shut-off in case of water leaks) or equipment damage?

I found a GB/5 mixing valve at espresso parts.com ($21).
[…]
The part listed by espresso parts is shown on page 35 (part 13).

It (part 13) gets cold water from a tee (bottom) on the steam boiler refill line, and outputs (through a check valve, part 12) to another tee (part 10), which mixes this regulated amount of cold water at pump pressure (9 bar from outside pump) with water(/steam?) coming from the steam boiler (from right of part 10, again through a check valve (page 37). The third outlet of the tee (part 10) is then going directly to the hot water solenoid (part 8 ), before ending in the hot water tap.

[…]
I've got the rest correctly set up:


Thinking again about the pressure differential issue, I have:
1. cold water from mains, regulated at ~2.5 bar (35 psi)
2. hot water from steam boiler, at 1-1.35 bar (1.35 at set temp, 1 bar when steam valve is opened)
3. hot water tap at 0 bar
It then seems like a "water mix valve", set at the correct opening, will deliver just enough cold water to the mixing tee to cool down the steam boiler water (~110°C to 75-100°C).

Now that I understand the setup in theory, where do I start with to actually do something?
- Where can I find in parts catalog the type/thread pitch/size of fittings used? How do I know different parts I would order online will fit together? All parts catalog I've looked at don't say a word on this.
- If I want to put everything together using plastic (teflon?) tubing, what kind of fittings will be required?
- Can I simply assume parts/fittings from LaSpaziale could fit with parts from LaMarzocco (thread pitch, size)? (Wouldn't that be great!)
- Where can I get all these parts? Any repair shop? (Chris Coffee for LS? Espresso parts for LM?) Do they usually carry every part? (My order would be a mix of heteroclite parts).
- What is special about the mixing valve? Is it pressure regulated? If I buy this one made for a LM under 9 bar of pressure, would I need to be really lucky for it to fit under 2.5 bar with different water tubing sizes?

Does anyone have answers to these questions?

It is frustrating as this really seems to me like a good idea, I now know how to do it, but I have no idea where/what to procure to make it happen…

[Endo]

Personally, I don't like the taste of the old boiler water for my tea. I prefer good, fresh filtered water. My teas are very expensive and the flavours are very delicate (nothing like espresso at all). I can identify the boiler water every time, and it destroys the experience for me. This might be why you're not getting any answers to your request.

Perhaps your experience is different. Perhaps you change the steam boiler water more frequently than me. If so, then go for it.

Unfortunately I can't answer any of your "fitting" questions since they are very detailed, but I assume if you take the proper measurements, everything you need should be available online at a place like McMaster-Carr.

Honestly, I haven't heard of anyone else attempting this before, so you might need to pioneer this project on your own. Good luck!

[Louis]

Personally, I don't like the taste of the old boiler water for my tea. I prefer good, fresh filtered water. My teas are very expensive and the flavours are very delicate (nothing like espresso at all). I can identify the boiler water every time, and it destroys the experience for me. This might be why you're not getting any answers to your request.

Perhaps your experience is different. Perhaps you change the steam boiler water more frequently than me. If so, then go for it.

Endo, tu as semé un doute dans mon esprit...

I've took some steam boiler water out and tasted it after it completly cooled down, side by side with fresh filtered water. I can't tell which is which.

I do use the hot water tap to preheat cups, rinse the portafilter, preheat the Thermos bottle I bring to work with tea and tea water it self; so I probably pull about 1L / day. I also turn off the boiler before it finishes refilling, delaying this step until my next session.

In my experience, my steam boiler water tastes fine.

[Endo]

My last experience with steam boiler water was bad and I haven't tried it again since. But perhaps it had simply been in the boiler too long (sometimes I don't use the hot water for a long time, so perhaps the water in there had been reheated several times).

But really, the main reason is that it is just too hot for me. I usually use my Buono kettle on my gas stove to heat tea water, but I sometimes make tea with the brew boiler water (which is smaller so the water hasn't been there nearly as long). It seems to taste better and the temperature is almost perfect for the Oolong teas I brew (90C-93C).

Here's a picture of my hand made Yixing purple clay pot for Oolong (along with a photo of the lady who made it for me). I simply heat it up and fill it under the portfilter!

Yixing Tea Pot

IMG_1252 (2) (360x240).jpg (75.73 KiB) Viewed 19197 times

[oton]

Same experience here. Don't like the taste from the boiler, so I don't use it for hot water, only for steaming. Not a very big issue... but the real problem is that the water taste from the group do not taste like fresh water (cool it down), so I'm pretty sure that it must be affect the espresso flavor.

[Louis]

My last experience with steam boiler water was bad and I haven't tried it again since. But perhaps it had simply been in the boiler too long (sometimes I don't use the hot water for a long time, so perhaps the water in there had been reheated several times).

It's probably the case. I might also be related to the cold water reservoir of the Mini vs my plumbed-in.

But really, the main reason is that it is just too hot for me.

What about adding a hot water mixing valve to correct this?...

I usually use my Buono kettle on my gas stove to heat tea water, but I sometimes make tea with the brew boiler water (which is smaller so the water hasn't been there nearly as long). It seems to taste better and the temperature is almost perfect for the Oolong teas I brew (90C-93C).

Here's a picture of my hand made Yixing purple clay pot for Oolong (along with a photo of the lady who made it for me). I simply heat it up and fill it under the portfilter!

Off Topic

Personally I would not use the water from the brew boiler. While it doesn't taste stale, it tastes like coffee/old coffee oils... (I had tested this: pull some water, let it cool down, taste). Note that I do clean my group well: Pallö brush after each shot/session, water backflush every week, cleanser backflush every 1-2 weeks (I only pull 2-3 shots a day).

Nice tea pot. I bought a nice hand made clay zhōng (a.k.a. gaiwan) and have been buying green teas (mostly sencha) for years from Un amour des thés (for naturally aromatized teas (dried flower blossom, etc.); I particularly like their Jasmin Dragon d’or des Nuits de Mai - Bio, Sencha Diabolo aux épices, Sencha Sakura aux cerises and Sencha aux fruits exotiques et gingembre) and Camellia Sinensis (for pure origin sencha / gyokuro teas). I take the former at work in a Thermos (made in the morning), and the latter in the zhōng on the week-ends when I have more time to make it / appreciate it.

The zhōng is really nice: pouring boiling water in it gives perfect 75-80°C water 1 min later, as it absorbs exactly the correct amount of heat. Really nice!

I will probably be buying a nice bamboo tea boat to go along with it on my next visit to Camellia Sinensis. I bought my wife their book, book: THÉ: histoire, terroirs, saveurs but haven't read it yet.

I'm still looking for a place to buy a better Nissan thermos bottle in Montréal; I can't justify the shipping costs for only one item from online stores.

[Louis]

CROSS-POST ON HB

I've spent some time yesterday perusing through both the LaSpaziale Vivaldi/MiniVivaldi/Rossini parts catalog (hosted here) and the La Marzocco GB/5 parts catalog and found the needed parts to realize the desired setup.

I've put everything together HERE (PDF), along with part numbers from LS / LM (sorry, can't put it here as an image, would be completely unreadable).

The whole setup should be about 5" high (very approximate measurement, using screen scaling and a ruler on computer screen!) and would be fitted left and front of the steam boiler in the Vivaldi frame.

After answering most my original questions, some remains.

I will answer most by opening the machine this week-end to take some measurements and see if all should fit:

• Will the tee setup at the pump inlet fit (through hole in bottom of machine)
• Will the whole thing fit inside the frame (the biggest question in fact...)?
• Will the mixing tee fit (inlet from hot water check valve toward the back of the machine; tee outlet to solenoid toward front; need an elbow for the latter?)
• Take measurements for teflon tubing length to buy.
• Find how to hold the whole setup inside the machine.

I haven't figured out where to get an answer for some others (help will be much appreciated):

• Will the LM water mix valve work with mains line pressure of 2.5 bar instead of the 9 bars in the LM setup (put after pump). I would think so (should be adjustable enough). If not, I need to find another valve (I don't want to also play in the electrical wiring/control box to trigger the pump on hot water solenoid activation, to have it set up as in LM machines).
• Is there something special about the LM mixing valve? Is it pressure regulated? (in case I want to buy another brand than the OEM LM).
• Where can I get all these parts? Any repair shop? (Chris Coffee for LS? Espresso parts for LM?) Do they usually carry every part (my order would be a mix of heteroclite parts)? Anyone knows a good online source?
• What threading/pitch is used in Italian espresso machines (if I want to buy from online stores like McMaster-Carr instead of costly OEM parts from LS / LM)? Is it ¼" and 3/8" BSPP?
• How can I ensure the brass fittings I buy are NSF approved for water consumption?

I assume parts from LS and LM will simply fit together. I hope I'm right...?

More to follow after I see the feasibility of all this during the week-end...

[EDIT]: I forgot one part: to leave some space between the pump and the mains tee, I would keep the 1/4" male-male fitting on the pump and add a 1/4" female-female fitting between it and the tee (same fitting already used elsewhere in the setup).

[Endo]

Cool project. Excellent reference for others too!

[Louis]

Cool project. Excellent reference for others too!

Raining on Sunday. We'll then see if this is only a nice idea or a project!

[bgosselin]

I guess it turns out as a nice idea after all. :)

[Louis]

I haven't discarded the idea and went forward contacting Chris' Coffee for parts. With LM/LS sourced parts, it would cost me around 300$ and it would void my 2-year warranty.

The main problem is not knowing the OEM parts threading, else, I would have bought everything needed only from third parties.

Also, after taking some measurements, some parts would need to be shifted/moved compared to my original plan, but I confirmed everything would fit.

Then there is the issue of relying on one-way valves (to prevent line water to go into the steam boiler from the mixing tee) to avoid water overflowing the steam boiler (through safety valve, which is set lower than line pressure, or through the vacuum-breaker valve when cold). Idealy, one would use a solenoid for this (wired in parallel with the hot water solenoid/pump), but this adds another layer of complexity (this would allow line cold water to enter mixing tee only when the pump is running, ensuring cold water could only flow in the correct direction).

So... yes, I have kept this as an idea for now...