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Thread: Priming, history, internal works and understanding

  1. #1
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    Priming, history, internal works and understanding

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    Dear all,
    Im not sure if this has ever been discussed in great detail. But, what actually is the purpose of priming?
    What is happening internally with the water, boiler and temperature?
    Can anyone please teach me?

    Cheers,
    Leo

  2. #2
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    Re: Priming, history, internal works and understanding

    what do you mean ?

    priming pump?
    priming the boiler (filling) before use?
    priming a shot (pre-infusion?)

    i need detail.... (cause i am sloooooow ) :D

  3. #3
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    Re: Priming, history, internal works and understanding

    uhm hehe. all three please.

    would like to start with the boiler if possible. ^^

    Thank you in advance, for your time and effort 8-)

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    Re: Priming, history, internal works and understanding

    Well leo you had better fill us in on what you have in machine variety etc.

    in general if its single boiler tank machine (brand new out of box)

    1. fill tank with filtered water
    2. turn it on and open steam tap
    2.5 turn on brew switch or water switch
    3. wait for water to come out steam wand
    4. close steam wand and wait for water to come out group head.
    5 turn off pump

    your now read to heat up as normal

    the effect of water 1st coming out the steam wand ensures your boiler is full, IMO this should be repeated after every time you make steam (that is refill the boiler as per 5 steps above)

    sunbeam 6900 thermoblock type machines are a bit different but your going to need to let it prime the system itself by following the owners manual.

    HX machines are a bit different, and if you are unsure we need mpore complete info about machine, water source, pump type etc to be any help.

    pre-infusion is a whole another post not by me :) as i dont do it

  5. #5
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    Re: Priming, history, internal works and understanding

    Wow, thanks maheel, mine is a new diadema perfetta, purchased from Chris of Talk Coffee (sorry for the constant hounding hehe). Its a single boiler dual purpose.

    I follow up to 4, but I dont see water coming out pf the grouphead, is this different with every machine?

    I guess I now understand more about priming, especially with regards to making sure the boiler is full.

    I guess this is something that is done since espresso machines come into existence?
    I need to read more about the history pf espresso machines and their evolution, and the changes in priming practises. And probably, get a book about the internal works of espresso machinaries ;)

    Thanks once again maheel.

    Btw, can anyone recommend me any books for reading about espresso machines and their internals?

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    Re: Priming, history, internal works and understanding

    thats a high end quality single boiler machine you have there and to be honest my steps where for the lower end (silvia, gaggia, breville etc etc machines)

    please follow up with chris at TC as he is an expert in his field where i am more a "hack" and there is highly likely a 3 way valve in yours (or some such mechanics) that does not let water out the GHead when "filling"

    highly likely he will be along soon to help you get on the correct "right path" :) and give a better explanation on what is happening inside your boiler

    but i am glad you understood "filling the boiler" idea. If steam is drawn from the top and water comes out the steam wand then "its got to be full" is my thought pattern :)

    empty boiler and turning on / not refilling = BAD.....

  7. #7
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    Re: Priming, history, internal works and understanding

    Why is it necessary to prime the boiler after steaming? Arent boilers self priming? I think my Gaggia sucks water up from the reservoir* when it cools after steaming using the same principle as the steam pumps that were invented at the dawn of the industrial revolution. I could be wrong, but since the simpler gaggias like the cubika have a self priming hose instead of the OPV return hose I assumed my classic could self prime through the OPV hose.

    Do some machines self prime and others not?

    I usually prime my machine about once a week in case some air has leaked into the boiler somehow.
    Please let me know if there is something I have missed and tell me why I should be priming more often.

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    Re: Priming, history, internal works and understanding

    If you dont fill the boiler after steaming on a Gaggia, it will have less water, so when you go to brew your next coffee you will be filling the boiler and will more cold water, you have a longer wait and maybe colder brew temp.

    I always prime my boiler by opening steam wand and pumping out water after drinking my coffee, keep the inside clean of steam wand clean too. I also empty my puck so machine is clean and read for next time.


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    Re: Priming, history, internal works and understanding

    I dont know the Gaggias but the Silvia and Lelit are definitely not boiler self priming/filling.* I found a useful guide with diagrams - google for "Diagram of Silvias Boiler" (commercial link).

    The HX+ level machines are only boiler self priming/filling because they have level sensors in the boiler and a control box which runs the pump and opens the filling valve when required.* All that kit has cost and physical impacts that are difficult for small domestic machines like the Silvia.

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    Re: Priming, history, internal works and understanding

    Everything FP said.
    The pump is self priming. The boiler has to be manually topped up.

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    Re: Priming, history, internal works and understanding

    Hey scarey, thanks for the link. The diagrams do help alot! :)

    i found this too from another post by Mal
    http://home.surewest.net/frcn/Coffee/3way/intro.html

    good read :)

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    Re: Priming, history, internal works and understanding

    Quote Originally Posted by 7C6C6E7D6A760F0 link=1307763246/8#8 date=1307841932
    google for "Diagram of Silvias Boiler" (commercial link).
    Wow thats a excellent article , very detailed information. thanks for sharing scarey

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    Re: Priming, history, internal works and understanding

    Quote Originally Posted by 537C6770657A627067150 link=1307763246/11#11 date=1307877057
    Wow thats a excellent article
    I particularly liked the phonetic pronounciation guide for some of those tricky Italian words. cop-poo-chee [ch769]-know anyone? ;D

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    Re: Priming, history, internal works and understanding

    Okay.
    Quote Originally Posted by 47575546514D340 link=1307763246/8#8 date=1307841932
    he HX+ level machines are only boiler self priming/filling because they have level sensors in the boiler and a control box which runs the pump and opens the filling valve when required.
    I was thinking about a passive self-priming mechanism working on the same principle as the savery steam pump (an interesting footnote in engineering history). In the case of a coffee machine when it steams away some of its water the rest of the boiler is full of steam, not air. When it cools below boiling then the pressure in the boiler will be less than the external pressure. Either it maintains this negative pressure or it lets in some air or water. I suspect in the Gaggias at least it lets in some water through one of the hoses to the tank, passively "self priming".

    I came to this conclusion because I saw on a parts diagram for the Gaggia Espresso that there is a suction hose connected to a "self priming valve assembly". What does it do if it doesnt let some water into the boiler?

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    Re: Priming, history, internal works and understanding

    Quote Originally Posted by 5A5657585717565B4B505C57390 link=1307763246/13#13 date=1307884191
    I came to this conclusion because I saw on a parts diagram for the Gaggia Espresso that there is a suction hose connected to a "self priming valve assembly". What does it do if it doesnt let some water into the boiler?
    Interesting... a bit of googling and I found this about the Gaggia Self-Priming Valves which suggests "The self-priming valve is designed to permit air-pressure in the boiler to escape, eliminating the possibility of an air- lock, which prevents the boiler from filling properly."

    Doesnt sound like what you were thinking but instead saves you from having to open the steam valve while priming the boiler?

    Self-priming the boiler using the vacuum sounds a bit dangerous - OK if you normally only steam 2 or 3 drinks a session but then I suspect that too many people would forget about priming and keep steaming away on the odd occasion they have guests around.

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    Re: Priming, history, internal works and understanding

    Behmor Brazen - $249 - Free Freight
    Interesting.
    That same article says "The pea-valve1 in the unit is designed to prevent the flow of steam and hot water from the boiler to the water reservoir" which makes me think that water can be sucked from the reservoir into the boiler.

    So Im not sure but Im still leaning towards the self-priming by suction explanation. Does anybody out there know?



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