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Thread: ExporBar MegaCrem Pressure and Temp Question

  1. #1
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    ExporBar MegaCrem Pressure and Temp Question

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    Hi All

    Thanks for reading my post.

    I recently purchased a bit of a project machine as I was keen to understand coffee better. I picked up a ExpoBar Megacrem GR1. I have had to strip it down and rebuild parts and it seems to be working okay. I just have a coule of questions around pressure and temp.

    Firstly, My pressure is set to 1.1Bar, but the machine will cool down to 900 before the boilers kicks in and pushes it back up. Is this normal?

    Should my upper or limits be pushed up a little? I would of thought 900 on the guage was too low, and would want to cater to worst case pressure?

    How do I adjust the pressure. I have a sirai pressurestat with a yellow dial. But turning this either ways does not seem to do anything. What does this do? I expected it to increased and decrease boiler pressure.

    I read that boiler pressure and temp are related. So I can not adjust the temp at the group head and extraction point? It feels coolish (definetly not 93c. How can i best test?

    Also, the boiler is not insulated. Found that a bit odd. If I insulated it would i get better consistency in heat loss. If so what would you recommend insulating it with?

    I know I have alot of questions there. Would really appreciate if you could help this newb out.

    Thanks

  2. #2
    Senior Member sprezzatura's Avatar
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    Quote Originally Posted by RyanG View Post
    Hi All

    Thanks for reading my post.

    I recently purchased a bit of a project machine as I was keen to understand coffee better. I picked up a ExpoBar Megacrem GR1. I have had to strip it down and rebuild parts and it seems to be working okay. I just have a coule of questions around pressure and temp.

    Firstly, My pressure is set to 1.1Bar, but the machine will cool down to 900 before the boilers kicks in and pushes it back up. Is this normal?

    Should my upper or limits be pushed up a little? I would of thought 900 on the guage was too low, and would want to cater to worst case pressure?

    How do I adjust the pressure. I have a sirai pressurestat with a yellow dial. But turning this either ways does not seem to do anything. What does this do? I expected it to increased and decrease boiler pressure.

    I read that boiler pressure and temp are related. So I can not adjust the temp at the group head and extraction point? It feels coolish (definetly not 93c. How can i best test?

    Also, the boiler is not insulated. Found that a bit odd. If I insulated it would i get better consistency in heat loss. If so what would you recommend insulating it with?

    I know I have alot of questions there. Would really appreciate if you could help this newb out.

    Thanks
    Hi

    Expobars are set at 1.2 bar. This corresponds to appx. 121C and the drop to 0.9 bar before the pressure switch engages load again is called deadband. This is normal and your switch is fine.

    Turning the yellow plug on the pressure switch won't do anything because you will need to remove that plug to access the slot bolt that controls the diaphragm membrane resistance (which is under the yellow plug).

    A high-temperature foil insulation can be used to insulate the boiler. Check with a water service supply company.

  3. #3
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    Thanks For the reply.

    Feel a little silly re the yellow dial on the pressurestat now

    So would you recommend insulating the boiler or not? Is it going to make for better performance?

    So Looks like I am all set. Thanks for the input.




    Quote Originally Posted by sprezzatura View Post
    Hi

    Expobars are set at 1.2 bar. This corresponds to appx. 121C and the drop to 0.9 bar before the pressure switch engages load again is called deadband. This is normal and your switch is fine.

    Turning the yellow plug on the pressure switch won't do anything because you will need to remove that plug to access the slot bolt that controls the diaphragm membrane resistance (which is under the yellow plug).

    A high-temperature foil insulation can be used to insulate the boiler. Check with a water service supply company.

  4. #4
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    coffee splutter

    Hi Guys

    Can someone watch the video link and tell me whats going on.

    I think i have a splutter and there is something wrong with the machine.
    It is set to 1.2bar and stops, so i dont think its overheating.

    When i pour a shot it starts nice, and then splutters. The video shows without a portafilter but can clearly see the splutter. Would really appreciate your thoughts.

    Thanks

    https://youtu.be/rwTmswX2BQk

    btw: expobar megacrem.

  5. #5
    Senior Member sprezzatura's Avatar
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    Hervey Bay, QLD
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    ExporBar MegaCrem Pressure and Temp Question

    Quote Originally Posted by RyanG View Post
    Hi Guys

    Can someone watch the video link and tell me whats going on.

    I think i have a splutter and there is something wrong with the machine.
    It is set to 1.2bar and stops, so i dont think its overheating.

    When i pour a shot it starts nice, and then splutters. The video shows without a portafilter but can clearly see the splutter. Would really appreciate your thoughts.

    Thanks

    https://youtu.be/rwTmswX2BQk

    btw: expobar megacrem.
    Hi,

    You have an issue with water upstream from the group. Your shower looks clean. My guess is water delivery after the flow meter to the injector, HX, potential scale in fitting at top of boiler (a culprit), and possibly in the group (screen, jet and PTFE assembly).

    Do the keypad lights ever flash?
    Last edited by sprezzatura; 18th May 2016 at 11:23 PM.

  6. #6
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    No the keypad lights are always perfect.
    I took out the group head and stripped and cleaned it as best I could. It seemed ok (not that I am an expert).

    So whats the best way forward? Can I descale the unit easily?

  7. #7
    Senior Member artman's Avatar
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    Check for scale build up and descale of necessary. There is a guide here on how to descale a hear exchange machine.

    Cheers

  8. #8
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    Thanks for the advise. Really helpful!

    One last newbie question, I cant find guides anywhere? Can you point it out to me?

  9. #9
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    All Good. Found it using a google search instead of coffeesnob search



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