Announcement

Collapse
No announcement yet.

Magister E61 Head - Backflush weekly causes overpressure issues.

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Magister E61 Head - Backflush weekly causes overpressure issues.

    Im giving my machine a weekly back-flush and have noticed an issue.

    After ive been through the cleaning process whenever the head gets stressed (i.e. pulling a shot...) my boiler pressure meter shoots up and if left running the OPV vents.

    Im thinking that the cleaning is exposing a problem with a sticky valve in the E61 head, exposing the low pressure plumbing to the high pressure flow allowing the water flow to complete the loop back to the boiler at high pressure through the pump action.

    Does this seem feasible?

    Alternatively the pressure-stat could be fault but I cant fathom how that would result in the over-pressure scenario when pulling a shot, surely it would just vent through the puck more than back to the boiler?

    Give it a day and it settles down, albeit ive noticed once that if the head gets choked it happens from time to time (sorry im new at this game... im still experimenting with tamping, grinding etc.).

    Going to pull the head apart sometime soon, need to try get some seals first though - maybe a seal is the problem...

  • #2
    Re: Magister E61 Head - Backflush weekly causes overpressure issues.

    Originally posted by 0633282A2E2400352820470 link=1328519638/0#0 date=1328519638
    After ive been through the cleaning process whenever the head gets stressed (i.e. pulling a shot...) my boiler pressure meter shoots up and if left running the OPV vents.
    Im no expert - but since the pump puts out 15bar, the OPV must vent... unless youre running crazy amounts of water through..

    Originally posted by 0633282A2E2400352820470 link=1328519638/0#0 date=1328519638
    Im thinking that the cleaning is exposing a problem with a sticky valve in the E61 head, exposing the low pressure plumbing to the high pressure flow allowing the water flow to complete the loop back to the boiler at high pressure through the pump action.
    The OPV should open on the cold water feed before the boiler and dump excess back into the tank..

    /Kevin

    Comment


    • #3
      Re: Magister E61 Head - Backflush weekly causes overpressure issues.

      Took the top and bottom assemblies off the head, to be honest was amazed how clean it was inside.. some darkening of the brass components and a couple if very minor buildups on the mushroom were the only evidence of use. We dont have much by way of scale buildup here in sydney but I suspect the machine hasnt done much work. The only minor point to call out was the bottom seal looked as though it could do with a replacement it was still very serviceable.

      Thanks for your comments KJM, I probably described the wrong release valve then. The one venting seems to be related to the boiler and it happens when the boiler pressure exceeds 2.5 bar and is followed by a release of steam inside the machine... not nice, but ive yet to do this with the cover off to see which component it is.

      Comment


      • #4
        Re: Magister E61 Head - Backflush weekly causes overpressure issues.

        Digging away at this.

        Looks like the pressure stat is sticky which isnt good but at least its replaceable. Its a Ma-ter XP110 going by its markings.

        I tested this by repeatedly purging the pressure and looking to see when the pressure stat switched on and off. It consistently detects low pressure around 0.9 bar but doesnt switch down until somewhere between 1.2 and 1.7 bar. Its adjustable but the huge variance seems to remain.

        Whats more worrying is the expansion valve, it seems to constantly leak. It spurges water a little as the machine starts (is this normal? It might be - it has a water catcher built in) but it never completely closes - I can hear a constant hiss even when the tank is up to pressure.

        Ive included a picture below, but it looks like the middle one on the coffeeparts page (http://www.coffeeparts.com.au/misc/expansion-valves) - sorry for the commercial link.

        Any thoughts? Should this be constantly venting (albeit a small volume...)?


        Comment


        • #5
          Re: Magister E61 Head - Backflush weekly causes overpressure issues.

          That is the anti vac valve. It spits a bit when the boiler startes to get pressure, then the positive pressure inside the boiler forces it shut. It should not continually leak. You can easily replace the entire valve or take yours off and clean it/replace the sealing o ring.

          Cheers

          Comment


          • #6
            Re: Magister E61 Head - Backflush weekly causes overpressure issues.

            Originally posted by 0D382321252F0B3E232B4C0 link=1328519638/2#2 date=1328707440
            Thanks for your comments KJM, I probably described the wrong release valve then. The one venting seems to be related to the boiler and it happens when the boiler pressure exceeds 2.5 bar and is followed by a release of steam inside the machine... not nice, but ive yet to do this with the cover off to see which component it is.
            OK - so that is the primary safety device - the boiler over pressure (aka "anti-bomb") valve. Seems like it is doing its job, and the fault is as you have diagnosed - the pressurestat not doing its job. Im not sure what the deadband for that pressurestat actually is, but replacements can be got from Pedro at CoffeeParts <----. I do know that the adjustment screw on those is pretty sensitive.

            As artman said regarding the anti-vac valve - you can take it apart and clean or just replace. Theyre not expensive - you just need to know what thread to buy. They seem to scale up pretty easily!

            /Kevin

            Comment


            • #7
              Re: Magister E61 Head - Backflush weekly causes overpressure issues.

              Cheers guys. Would prefer to repair than replace the anti-vac but I typically have find problems getting hold of the correct o-rings etc...

              Im slowly building up a parts list... not an ideal situation after buying something but at least I know afterwards its been serviced and is fully functional.

              Theres a few other things Id like to do to the machine, time and cash willing, things such as:

              . Add a boiler indicator (to see when the heat is on).
              . Add a water level indicator, and ideally plumb the machine into the mains.
              . Dual meter - Both Boiler and head pressure.
              . Naked porta.
              . Head temperature sensor.
              . Timer.

              A lot of it is fantasy

              Comment


              • #8
                Re: Magister E61 Head - Backflush weekly causes overpressure issues.

                I got my o ring from a bearing supplier, they normally have a huge range.

                Cheers

                Comment


                • #9
                  Re: Magister E61 Head - Backflush weekly causes overpressure issues.

                  Churned out 8-9 mugs (sorry its a brit thing I think...) of flat whites this morning. Once I got over the initial leakage phase of the anti-vac all was good. Everyone was more than happy, me especially.

                  Not sure how much impact the varying boiler pressure has on the actual extraction process, im assuming its likely to affect the steaming more as being a HX machine it has an independent flow. Only thing that sticks in the back of my mind is that the water temperature will rise in the boiler as the pressure increases which will affect the heat exchange process.

                  Orders a fair list from Coffee Parts - Head seals, set of seals etc. to refurbish the inside of the E61 assembly, new Anti-vac, new pressure stat, a dosing spoon (my current dosing process is woeful, and a few other minor items. Hope it turns up soon, cant wait to fit it all...

                  Comment


                  • #10
                    Re: Magister E61 Head - Backflush weekly causes overpressure issues.

                    Yep, the higher the boiler pressure, the higher the temp of the water in the boiler and hence hotter brew water via the heat exchange process.

                    Cheers

                    Comment


                    • #11
                      Re: Magister E61 Head - Backflush weekly causes overpressure issues.

                      Originally posted by 4D786361656F4B7E636B0C0 link=1328519638/6#6 date=1328867012
                      Theres a few other things Id like to do to the machine, time and cash willing, things such as:

                      . Add a boiler indicator (to see when the heat is on).
                      . Add a water level indicator, and ideally plumb the machine into the mains.
                      . Dual meter - Both Boiler and head pressure.
                      . Naked porta.
                      . Head temperature sensor.
                      . Timer.
                      Heat is on? - get a Neon indicator (couple of dollars for one with a nice bezel).

                      Water level (I assume you mean the tank) - can be done - and there are lots of ways.

                      Dual meter? Hmmm - that depends on space! I was going to put one in the Oscar I have but there is precious little space to actually fit it in. Theyre also not all that accurate, BTW! Check CoffeeParts for pricing and the sorts available.

                      Head temperature? You can put a probe down the bolt hole in the front of the head pretty simply (Swagelok have an adaptor thatll seal around a standard probe type thermometer. Google "E61 temperature Probe" for lots of information..).

                      So all do-able. Sounds like my kind of fun, actually ;D

                      /Kevin

                      Comment


                      • #12
                        Re: Magister E61 Head - Backflush weekly causes overpressure issues.

                        Added a new (used) grinder to the setup, thanks to a very generous price from a neighbour whos in the coffee business.

                        Ive essentially gone from one extreme to the other with a Rancilo MD50 AT. Not sure how ill manage the waste with it., maybe ill just use it on Saturday mornings when I have to make 1/2 dozen coffees at a time.

                        Comment


                        • #13
                          Re: Magister E61 Head - Backflush weekly causes overpressure issues.

                          Fitted new internal seals to the E61, new pressurestat and group head gasget.

                          Bought a 3/8 anti-vac valve but oddly the original has a slightly smaller thread, somewhere between 3/8 and 1/4 bsp - possibly metric. Will check again at the weekend, might just be an optical illusion, if not ill take some measurements.

                          Net effect -

                          Boiler pressure is much more stable, heater starts at around 1.05bar and switches off around 1.15bar. Is this optimal? should I go up/down? looks like i can calibrate to within 0.1 bar give/take.

                          Portafilter has a nicery insert feeling - not surprising, the old seal was hard as nails and had cracks 1/2 way through by the time i removed it for the 3rd time.

                          Internal seals were less ideal than I orginally thought... was totally bemused for a while though when trying to replace them, really wasnt expecting the seal assemblies to unscrew.

                          1st shot... cant say I can see much difference, not surprised... crema looks better but thats probably me wishing it to look better. Had to run a few mins of water through though and use the lever a bit to ensure that theres no residual rubber taste from the seals.. hopefully i wont get any.

                          Oh and many thanks to CoffeeParts - sterling delivery service

                          Comment

                          Working...
                          X