Buying grouphead for homemade espresso machine - Page 3

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Nbudor

Postby Nbudor » Feb 05, 2019, 9:01 am

I'm in the process of acquiring all the necessary components for a E61 diy project, so I've been haunting ebay and local junk yards and flea markets for parts. It's been loads of fun so far, reminds me of that old Johnny Cash song 'One piece at a time' :D
I actually wanted to restore an old machine, but my bids were too low or shipping cost was prohibitive, so I decided to scavenge for parts.
If you dont mind a used boiler, the fiscally conservative way to get it would be from a used vending or office type all-in-one machine - I've bought a used Carimali HX boiler,with heater, safety valve, level probes etc for about 50 Euro (of course, it's a bit too big for the frame that I plane using but that's another story).Anyway there's a bunch of WMF and Franke boilers floating around on the market.

b1063n

Postby b1063n » Feb 05, 2019, 9:16 am

I will surely post pictures once I have something photograph worthy.

I will first just focus on making the brewing boiler and get it to work. Testing the heater and PID at atmospheric presurre and then under pressure. The steam boiler will come after that.

One tricky part to get locally in china was the OPV valve, I had to buy one from an expobar office machine, this opv is connectected to an ulka ex5, so i hope that does the trick. I found a myriad of OPVs meant to be used in an industrial enviroment which would do the trick, but they go for around 50usd or more and are not NSF.

I will post an hydraulics schematic and the parts emplyed once i make a decent version other people can understand hehehe

Having a hardtime deciding between digital pressure gauge or just a conventional. So i havent purchased that.

And my E61 is stuck in customs at the moment, but i should get it soon.

Nbudor

Postby Nbudor » Feb 05, 2019, 10:27 am

b1063n wrote:One tricky part to get locally in china was the OPV valve, I had to buy one from an expobar office machine, this opv is connectected to an ulka ex5, so i hope that does the trick.

Wish you mentioned this before. This is at the same place you got the group from:
https://www.cis-spareparts.com/en/136181.html

b1063n

Postby b1063n » Feb 10, 2019, 1:31 am

Hi Nbudor

woaah those are some cheap OPV valves, too late now hehehe. :cry:

So about the HX boilers, I personally hate that design. Let me make clear again that I am a newbie when it comes to coffee machines hehehe, so please correct me if I am wrong.

It seems to me that HX boilers are just a "cute trick" to save money for mass scale production of coffee machines. I don't see any advantage at all otherwise. I think an HX boiler spells a loooot trouble for a custom built 4-6 espresso a day machine.

So in conclusion, I am of the opinion that having your steam boiler temp and your brewing water temp somehow linked within the same "heating circuit" makes no sense at all to me, no thanks. Unless its a money thing then yes, that makes sense.

Greets
Luis

b1063n

Postby b1063n » Feb 10, 2019, 1:58 am

As promised here is my first version of the hydraulics. Its the first version so it might need some changes. (and it might also have mistakes :roll: )

I managed to reduce the machine interface to four things
Brewing:
-E61 Lever
-Brew pump switch

Steaming:
-Steam wand valve
-Steam pump switch

I choose to have two pumps because the prices of solenoid valves is out of control. Pumps on the other hand are very cheap in comparison.
Having two pumps also simplifies the control system as no solenoid valves are needed.

The heating controls are 100% independent and start working by themselves as soon as all safety conditions are met.
-PID heating system for brew boiler
-Pressure stat system for steam (its cheaper and simple)

Here are the procedure instructions to fill the boilers and to brew or steam milk

Brew boiler operation

Filling brew boiler
1-Make sure E61 lever is pointing upwards (open)
2-Move brew pump switch to on position
3-Wait for water to come out of E61 head (wait a few seconds)
4-Move the E61 lever to the down position (pointing downwards)(closed)
5-Wait for water level sensor to be ON (PID starts working at this point)
6-Move brew pump switch to off position

Brewing
1-Raise E61 lever (wait 2-3 seconds for pre infusion or don't, whatever...)
2-Move brew pump switch to on position (coffee starts brewing)
3-Move brew pump switch to off position whenever your you want to stop brewing
4-Move the E61 lever to the down position (pointing downwards)


Steam boiler operation

Filling steam boiler
1-Move steam pump switch to on position
2-Steam pump stops when boiler is full, at the same time pressurestat starts operation
3-Move steam pump switch to off position

Using steam wand
1-Open steam wand
2-Close steam wand
3-Refill steam boiler if needed (follow filling boiler instructions)

Image

User avatar
kolu

Postby kolu » Feb 10, 2019, 4:01 am

few comments:
- don't use antivacuum valve in brew boiler, and you also don't need level probe there. just fill it before switching on the heater (this happens just once, no worries about that later).
- if you want level and safety sensor for steam boiler (in case of mixing water and cold water for tea delivery) make them both hang from top. that N.C. for level switch pump is... I don't know, I would just drop there some dead standard Gicar level controller.
- don't fill the steam boiler from top and don't put pressure gauge on the same line - it's better to have its own separate connection to boiler or to hang it from the pressostat connection, whatever works. but not the fill pipe.
- if you put the brew pressure manometer to the boiler (or at least after the check valve), it can be used to diagnose the internal conditions in the boiler (safety OPV function, etc.), whereas in your schematic it's nearly useless. you can also separate the pump OPV with ball valve from the rest, just to be able to close it and set the brew boiler safety OPV first (I would also go for 12 Bar).

b1063n

Postby b1063n » Feb 10, 2019, 4:45 am

Hey Kolu!
Thanks for the pointers! They are really useful.

kolu wrote:few comments:
- don't use antivacuum valve in brew boiler, and you also don't need level probe there. just fill it before switching on the heater (this happens just once, no worries about that later).

Good point, you are right. I can just fill the tank with the E61 open until water comes out and that should guarantee the tank is full.
The only reason I wanted the level sensor is as a safety measure so that the heater doesn't run dry, but if no one drains the tank secretly at night :wink: , or rather I always make sure its full before using, it should not be needed.
And regarding the anti vacuum valve, I was not totally sure about it anyways. Need to experiment a bit first.


kolu wrote:- if you want level and safety sensor for steam boiler (in case of mixing water and cold water for tea delivery) make them both hang from top.

I dont care for hot water delivery, if I ever implement that, the hot water will come from the brew boiler drain valve. But I don't want hot water.


kolu wrote:that N.C. for level switch pump is... I don't know, I would just drop there some dead standard Gicar level controller.

That N.C. level switch is indeed a bit meh... In fact it is redundant with pressurestat level sensor, will need to work on that.
What is a cigar level controller? btw?


kolu wrote:- don't fill the steam boiler from top and don't put pressure gauge on the same line - it's better to have its own separate connection to boiler or to hang it from the pressostat connection, whatever works. but not the fill pipe.

Yep, my bad here. LOL


kolu wrote:- if you put the brew pressure manometer to the boiler (or at least after the check valve), it can be used to diagnose the internal conditions in the boiler (safety OPV function, etc.), whereas in your schematic it's nearly useless. you can also separate the pump OPV with ball valve from the rest, just to be able to close it and set the brew boiler safety OPV first (I would also go for 12 Bar).

Yes, so I actually dont know where exactly to put the brew gauge, but you have some good points, Ill put it after the check valve.
Noted 12 Bar! I need to see how fast the pump OPV can react and to see if there are no spikes that might false trigger the safety OPV. But yes, better to be conservative.

User avatar
kolu

Postby kolu » Feb 10, 2019, 10:45 am

b1063n wrote:That N.C. level switch is indeed a bit meh... In fact it is redundant with pressurestat level sensor, will need to work on that.
What is a cigar level controller? btw?


Well, pressurestat will only keep the pressure constant and wouldn't trigger boiler fill, it's just switching on the heating.
You need a level probe and some sort of electronic controller (autofill controller) for that. Gicar is one of the companies that manufacture such controllers. You hook it up to mains, level probe and its output triggers fill valve and pump. In your case only the pump.

b1063n wrote:I need to see how fast the pump OPV can react and to see if there are no spikes that might false trigger the safety OPV. But yes, better to be conservative.


Pump OPV is instantaneous, no need to worry about that. I would suggest using Fluid-O-Tech vibration pump with their own bypass, it's the fastest I have seen and this combo produces by far the most constant pressure I have seen with any vibration pump. Although Ulka EX5 have few advantages (namely - self-priming with 0 input pressure).

Excessive margin in brew boiler OPV is then basically just unnecessary.

b1063n

Postby b1063n » Feb 10, 2019, 11:17 pm

kolu wrote:I would suggest using Fluid-O-Tech vibration pump with their own bypass, it's the fastest I have seen and this combo produces by far the most constant pressure I have seen with any vibration pump. Although Ulka EX5 have few advantages (namely - self-priming with 0 input pressure).

Did not know Fluid-O-Tech made solenoid pumps as well, I found the pump you mention and it is indeed a very nice "all-inclusve" solution. Maybe when my ULKA dies I'll replace it with a better one.
Though, ULKAs are available by the TON in China and very well priced.

Nbudor

Postby Nbudor » Feb 11, 2019, 7:41 am

b1063n wrote:
It seems to me that HX boilers are just a "cute trick" to save money for mass scale production of coffee machines. I don't see any advantage at all otherwise. I think an HX boiler spells a loooot trouble for a custom built 4-6 espresso a day machine.

So in conclusion, I am of the opinion that having your steam boiler temp and your brewing water temp somehow linked within the same "heating circuit" makes no sense at all to me, no thanks. Unless its a money thing then yes, that makes sense.

Greets
Luis

I think it's a cost and space (possibly?) saving method, plus in them olden days before microprocessor controllers, two separate boilers probably meant two level gauges etc, further complicating things (this is my guess, I'm just as a newbie on the subject as you are) .