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Thread: Boema Volumetric single group head and PID

  1. #1
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    Boema Volumetric single group head and PID

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    Am just new to the forum so hope I have chosen the correct place for my post and labelled it correctly. Please redirect if this is incorrect. I have had my Boema for nearly 6 years now after buying it from a local cafe and rebuilding the machine to new specifications. Although slightly large for a domestic kitchen, it has given great service with more than acceptable shots and occasionally outstanding ones. I have plumbed the Boema into my filtered water system as well. I use a local roaster and a Rancilio Rocky grinder. I have more time on my hands now and have thinking I want more consistent output from the machine, so have been thinking about a PID solution.

    Does any forum member have one of these machines that has a PID system installed? Can any member suggest an appropriate PID kit for this machine? Is a PID kit overkill for such a machine?

    Any comments gratefully received. I will trawl the forum posts to see if there are any relevant comments as I am new here but members might be able to direct me more efficiently. Thanks

  2. #2
    Senior Member WhatEverBeansNecessary's Avatar
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    After owning a Rocky for about 12 months, it's a great little machine but has some serious limitations. I would think about upgrading the grinder before a PID. A PID will certainly help, but the grinder will probably be more noticeable.

    The PID will help keep the machine more temp stable but with a large machine and properly warmed up, you probably wont notice a huge difference unless you are pulling shot after shot - although to be able to set the temperature (not sure if you can already) will be a huge bonus.

  3. #3
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    Quote Originally Posted by WhatEverBeansNecessary View Post
    After owning a Rocky for about 12 months, it's a great little machine but has some serious limitations. I would think about upgrading the grinder before a PID. A PID will certainly help, but the grinder will probably be more noticeable.

    The PID will help keep the machine more temp stable but with a large machine and properly warmed up, you probably wont notice a huge difference unless you are pulling shot after shot - although to be able to set the temperature (not sure if you can already) will be a huge bonus.
    Thanks for your thoughts WEBN, however the grinder cost me more than the Boema at the time. Amazingly I only paid $300 for the machine, (compared to the retail prices of around $3000 now) although additional replacement parts cost more than that. I thought about about a Mazza as an upgrade to the grinder but I am happy with the Rocky grinder for now (at $400). On the negative side, it is slow as a grinder, tends to lumpy grinds but on the positive side is consistent and does a fine grind. Not something for high throughput but perfectly good for home use and a definite improvement on the Sunbeam grinder I began with. I might borrow a large grinder from my roaster though, and see if that makes a difference to my pours and reconsider but it would have to be a significant improvement and not a marginal one to justify the expense.

    I know the machine can produce a very good espresso and believe it is linked to temperature and also pressure settings. I am also going to explore resetting the barometric pressure switch on it as well as the PID option. At present the Boema has a gauge that shows Steam psi, but I don't know how accurate it is or its functional use in making a shot of coffee. It has a red operating range that I use simply to assess if the machine has reached temp (or pressure) to use. I would like something that gives me more feedback, hence the PID thoughts.

  4. #4
    Senior Member WhatEverBeansNecessary's Avatar
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    PID will be able to give you better control of shot temperature/pressure and recovery back to the desired level. Not advocating against it, just the grinder seems like a more logical step to improve shot quality. Although sounds like you grabbed a bargain!

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    I am not familiar with the Boema line of machines other than having done a quick google search.

    In general though a PID is an improvement in consistency If the machine has a dedicated brew boiler to dispense the brew water from.

    If however it arrives at the GH from a heat exchanger that passes the heat from the steam boiler onto the brew water on the fly, the added value of a PID becomes debatable as far as consistency is concerned.
    It still allows for easier temperature adjustment. Since it is the steam boiler temp that is being controlled, the brew temp is merely derived from it and consistency in the brew temp is served by purging the GH before brewing (especially after long idle time). The brew temp settles in nicely when you are doing back to back shots regardless If it is PID controlled or not.
    Dimal likes this.

  6. #6
    Mal Dimal's Avatar
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    Well explained "degaulle"...

    Mal.

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    Senior Member LeroyC's Avatar
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    Yeah agreed, a PID on this type of machine is somewhat pointless. I get what youíre after, you want more accurate information feedback both before and during a shot, as well as a bit more control and consistency. Iím not so sure that a PID is the answer here.
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  8. #8
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    Thank you for the replies members. The issue then is whether I have an 'accurate' reading of temperature at the GH? This is a commercial machine with a large boiler and as far as I know it is a heat exchange system that is used. I have read that the optimum temp at GH for correct pour is 92 degrees. Perhaps I need to read more for understanding but I assumed a PID system was a controller for keeping temp at this level at the GH. If a PID is not the answer then how could I improve output from this machine?

  9. #9
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    The PID reading is usually linked to the boiler, NOT to the grouphead. What you see on the dial is either the steam boiler temerature, which is way higher than the grouphead temerature OR the steam boiler temperature offset to what the grouphead temperature is expected to be. By purging before brewing you get the GH as consistent as possible.

    What I would suggest is donít pay too much attention to what the gauge tells you, but focus on how you like your drink. If it tastes too bitter consistently and coarsening the grind setting doesnít help, drop the temperature by a degree or so (This is where the PID comes in handy). Donít get too hung up on whether it reads 92 or 94 degrees. How it tastes is where it counts.
    ernieg777 and level3ninja like this.



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