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Thread: Getting my Bezzera BZ35 to work

  1. #1
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    Getting my Bezzera BZ35 to work

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    Rather than have lots of question threads, ill just post in here as I go...

    I bought a BZ35 at a garage sale - condition unknown and looking like it had been unused for some time - tho left connected to water and vlaves closed up.

    Pics here.

    Its going to live in a ceramics workshop for the next year or two so on the shopping list is a good vinyl/canvas cover.



    First problem: safety valve stuck leaking

    Not having a manual or anything helpful I decided to plug nad plumb the unit in and see what power would do to it. I figured that if it went horribly wrong, the earth-leakage switch should save me ;)

    As soon as it got temperature in the boiler, the safety valve on top would leak and full up the small bowl with water.

    The pump would operate when getting water from the group, id get steam from the steam head but no water from the hot water spout... in other words - mostly working.

    Safety valve fixed by replacing the two-o-rings in the valve (probably not the 100% right sizes but close enough to work). I also added a small spring to ensure the vacuum/suck-back ball-valve inside it stayed shut while the boiler was heating up.

    fwiw: these safety valves are much like an air-compressor over-pressure safety valve.

  2. #2
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    Re: Getting my Bezzera BZ35 to work

    Problem 2: pump trying to refill boiler, boiler then running out of water/steam and heater+pump shutting down.

    (sorry if this rather long winded)

    Now that ive sorted out any visible leaks, the unit doesnt want to keep the boiler full for steam and hot water.

    I power it up and the heater and pump start - with the pump staying on for a considerable period of time. I open the steam and hot water valves to vent any air in that system, and pull on the safety valve to allow any air to escape from the boiler.

    I can hear water flowing thru a valve somewhere at this point.

    After a few minutes, ill start to get some pressure showing on the gauge but the pump is still noisily chugging away with what sounds like little success. Eventually, ill get just over 1bar on the gauge and the heater will start to turn on/off - this is the pressurestat working as designed.

    If i turn on the group to pull a blank shot, the pump turns on and when i turn the switch off, a small amount of water comes out the back-wash tube (name?) - this makes sense.

    If i try to pull a shot with the blind filter, nothing comes out the tube and eventually, i get a small leak of steam/water at the group seal and a bit more water out the tube when i turn off the pump.

    I can do these two things for as long as I like without loosing water supply to the head.

    But, after pulling water thru the steam and/or hot water valves, the pressure starts to drop on the gauge, and even tho the pump is now going again it seems to run out of fluid and both the pump and heater eventually turn off suggesting the tank is now low in water but high in temperature?

    Im now working my way thru the various bits of plumbing from water supply to boiler looking/inspecting for blockages.

    Ive found some small bits of plumbers tape inside but of most concern is the pump.

    I can easily rotate it (a good thing) but there seems to be very little suction on the inlet side and if i block off the outlet with my thumb, very little pressure builds up behind it.

    The anti-vacuum valve inside the pump works as designed - tho i havnt yet worked out if its sealing between the inlet/outlet.

    My experience with vane pumps is only with big vacuum pumps as found in diary/milking equipment but i figured that these are positive displacement pumps so you should get pressure building up in the outlet with some hand rotation of the pump?


    ... or maybe im not priming the boiler correctly?

    anyway, any advice on pump behaviour when hand cranks would be most welcome.

  3. #3
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    Re: Getting my Bezzera BZ35 to work

    It seems like fixing pumps is much like repairing a TV - give it a few good wacks, threaten to pull it apart without reference to a manual ... and it will suddenly start working.

    I put the pump in a soft-jaw vice, removed the back cover with some deft use of a brass drift and hammer to turn it, removed a small amount of scale and figured that any further disassembly required special tools, so I re-assembled it figuring I was up for a new pump.

    Out of curiosity, I re-fitted the anti-vacuum valve and the outlet/inlet brass fittings, attached a cordless drill to the shaft and then held the inlet under a slow running tap while i spun up the motor and held a thumb over the outlet - low and behold a whole lot of pressure built up and it was squirting water across the workshop (much to the delight of my canine supervisors).

    So the pump wasnt fubared but momentarily clagged up with something (im still to get some cleaning stuff from Pioneer Coffee at Yandina) so I figured that was the problem so I re-assembled the machine.

    Except now i get no steam or hotwater (but plenty of water from the group) and the heating element is open-circuit.

    Bugger.

    Im guessing that when it wasnt pumping correctly earlier, the boiler water-level got way too low and the element has failed. Ill also remove and clean the water level sensing rods incase theyre badly encrusted with scale.

    The boiler did have some grit and gunk in it so itll do it good to have a proper flush and drain.

    The heating element has a section that looks like newly heated copper (so its definately stuffed) so Ill have to order one from Coffee Parts and see what else is borked (or broken by me) on this machine.

    As I spend much of my time working on cars, its been pleasant to find fittings that havent been tightened up by idiots with air-tools at max torque. Im also having to re-think my opinion of italian engineering - their cars are pretty crap, but not their coffee machines it seems.

  4. #4
    Senior Member Koffee_Kosmo's Avatar
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    Re: Getting my Bezzera BZ35 to work

    You can get the schematic from the Barazi site

    http://barazi.com.au/content/view/44/141/

    Hope it helps

    KK

  5. #5
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    Re: Getting my Bezzera BZ35 to work

    Hi there. A lot of info there, but from a quick read it sounds like your boiler is running low. Id be checking the auto fill solenoid, and that there are no blockages along that path. If you have it plumbed in I would have thought that the boiler would still happily refill without the pump working.

    Good luck!

    Damian.

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    Re: Getting my Bezzera BZ35 to work

    I installed a new heater from Coffee Parts (fwiw: it arrived very quickly!).

    The element needed a bit of a bend to completely screw into the boiler (the element was hitting the heat exchanger) but Im guessing that theyre really for models with larger boilers?

    I took the opportunity to re-check and clean the auto-fill solenoid and the two one-way valves attached to it.

    Heater now works famously and pressurestat works over a wide range. At the moment ive wound it up so its off at about 1.4-1.5 bar and on at about 1.1 bar to try and force any bad joints to leak. So far nothing.

    I had to back off the bypass valve in the pump - when pumping thru the group, the small vent that drips into the tray area would flow.

    Ive left it running for a day at a time now and at first (e.g. within 5-10 minutes of power on), taking steam out of the boiler results major pressure drop, but from then on, it copes quite well with it. Group water temps are not fantastic but the workshop is exposed to the weather and its been windy lately. Am considering lining the inside of the covers with reflective insulation.

    Ive also been tinkering slightly with the height of the auto-fill sensor to get maximum steam production without quick changes in water levels. I cant remember how the sensors were positioned when I got it and Im guessing that this is a bit of black art?

    Next stop is Pioneer Coffee for cleaner and some decent grounds.

  7. #7
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    Re: Getting my Bezzera BZ35 to work

    "Ive left it running for a day at a time now and at first (e.g. within 5-10 minutes of power on), taking steam out of the boiler results major pressure drop, but from then on, it copes quite well with it."

    Hi!

    It shouldnt perform any differently first time you open the steam valve to how it responds later. Have you checked your anti-vac valve?

    Damian.

  8. #8
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    Re: Getting my Bezzera BZ35 to work

    Damian,

    by anti-vacuum valve, do you mean the safety valve on top of the boiler? Mine seems to be a combined over-pressure and anti-vacuum valve in one.

    If so, then I did have to put a spring in the inner section (anti-vacuum) as the ball wasnt seating correctly and it was leaking pressure when i first got the unit.

    Both o-rings inside it were replaced by generic items that i found (ashamedly...) in the o-ring collection in the workshop. Ive used the o-rings for all kinds of agricultural things (petrol, hydraulic fluid, water) so i am hoping theyre good for hot water. The over-pressure part of the valve seems to be healthy.

    Its fairly easy to get to - ill put it apart and have a 2nd-look.

    cheers,
    Charles.

  9. #9
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    Re: Getting my Bezzera BZ35 to work

    Hi, I dont know where it is located on your machine. I wouldnt bother pulling it apart. You can see if it is woring on by listening as it starts up. As pressure builds, you should hear steam escaping from the anti-vac valve for a second or so, then it will close. If you dont hear it close, then i may be stuck closed.

    Maybe there is no problem, if you are jut opening the steam valve before everything is heated up properly?

  10. #10
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    Re: Getting my Bezzera BZ35 to work

    update ... I decided to pull the machine apart ... it wasnt getting fully warm in the group head and I did remember when I replaced the heater that the boiler internals looked fairly ordinary.

    Boiler was utterly coated with baked-on scale and the heating path in the grouphead was completely blocked up.

    I went thru all my hydrochloric and citric acid descaling the boiler and all the metal parts. The crud in the bottom of the citric-acid bath is revolting. The hydrochloric is likewise polluted and diluted beyond re-use.

    Some pics are at the bottom of this page.

    Ive nearly completed re-assembly but have broken the small connecting fitting between the 3-way connector and the safety valve (bit circled in green)


    The broken bit look like this now (but with better focus):


    Is most frustrating as I cant see anything resembling it on coffeeparts.com *... and I dont know whether i should try someone more engine-oriented like Pirtek or Enzed to get them to fabricate something.

    The machine is looking better now that the crud is gone off most of the piping... but Im now at a stand still.

    I could start a wanted advert for old, broken Bezzeras but the Ministry of War and Finance may take issue with me collecting more stuff.

  11. #11
    Senior Member Koffee_Kosmo's Avatar
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    Re: Getting my Bezzera BZ35 to work

    Try Barazi as they are the importers
    It may be inexpensive as its a brass fitting

    Does not hurt to ring and ask

    KK

  12. #12
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    Re: Getting my Bezzera BZ35 to work

    Quote Originally Posted by 776B66616A64606B76606870776671030 link=1217288703/0#0 date=1217288702
    Safety valve fixed by replacing the two-o-rings in the valve (probably not the 100% right sizes but close enough to work). I also added a small spring to ensure the vacuum/suck-back ball-valve inside it stayed shut while the boiler was heating up. *
    Quote Originally Posted by 776B66616A64606B76606870776671030 link=1217288703/5#5 date=1220491361
    I installed a new heater from Coffee Parts (fwiw: it arrived very quickly!).

    Heater now works famously and pressurestat works over a wide range. At the moment ive wound it up so its off at about 1.4-1.5 bar and on at about 1.1 bar to try and force any bad joints to leak. So far nothing.

    Ive left it running for a day at a time now and at first (e.g. within 5-10 minutes of power on), taking steam out of the boiler results major pressure drop, but from then on, it copes quite well with it. Group water temps are not fantastic but the workshop is exposed to the weather and its been windy lately. Am considering lining the inside of the covers with reflective insulation.
    i was having a read, great looking little machine and good to hear your bringing it back to life. :)

    to me it sounds like your antivac is not working properly, if your building pressure when 1st powering on and pump kicks in that does not sound right. When you say you 1st let of some steam and the pressure drops off then comes back up, seems to me its really not working. You want the antivac open during heat up untill it hisses a bit then closes, this stops the false pressure building up.

    if the pump is making pressure and then turns off via pstat, it may not be filling enough and may fry another element?. (false presure)

    might be better if when you 1st turn on open the steam wand untill you hear real steam then close wand again. I do this on my old Carimali as it needs a new antivac. Life is better if they work well but :).

    good luck with the broken part, i have some brass elbows like the one in your picture and a few other bits and pieces but not sure which bit of yours is "broken" they are not off a coffee machine just in my "pipe bits" box. but i cant get to them to 22-23 aug.

    Leeham


  13. #13
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    Now to get my BZ35 working like the factory intended!

    Epic thread dig (or is it a zombie thread? the machine has come back to life)

    So I have this in my kitchen now:


    After several years of neglect (and being used as a shelf for plunger-coffee & hot-chocolate hardware and supplies) I replaced the seals for the heat-exchanger and the heater (from coffeeparts.com.au - awesome service folks), so at last I have a leak-free machine

    The broken part mentioned previously was fixed ghetto style: broken bits replaced by two brass fittings, hose clamps and some thick-wall silicon hose pinched from my brother's home-brewing parts bin.

    Water supply is a 20litre drum or rainwater atop cabinet behind the machine (so no issues with water supply to the pump).

    It's happy to spend hours idling at 1.1bar and after warming up, it steams up a warm jug of milk faster than the microwave and the boiling water outlet is handy for plunger coffee and tea. Boiler refill seems to occur when required and no strange sounds or issues happen when it does.

    But..... after being pulled apart numerous times, I am unsure of where the water-level sensors should really sit in the boiler (I understand how it and the low-water sensor work, but getting the right height is obviously something of a black art) ... and to make matters worse, the flow rate from the pump has been cranked right down (probably from me disassembling the relief valve on the pump and not remembering the settings previously) or is this an indicator of the mesh filter in the head being borked?

    So can anyone point me in the direction of a thread/reference that can help me dial this thing in WRT pump flow rate and low/high water levels for the boiler?

    ...


    and totally off topic, I saw these two cool looking machines at the antiques market in Paddington (Brisbane) early in the year. In hindsight, I should have bought at least one but that day I was on a mission to get shoes and a gift. Anyway, thought someone might find them of interest.

    Electric percolator (complete tho probably electrically unsafe).


    Stovetop unit (at least I think so, the base and stand was quite solid/heavy and I couldn't see any other way for heating the engine). Was missing parts (around pressure/refill seal at top and shower & seal in the head).

  14. #14
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    Not a huge amount of luck on flow rates and water level info, but I did find this on coffeegeek:
    The flow rate was set at about 60 ml in 30 seconds
    which gives me something to aim for when adjusting the pump relief valve and re-inspecting the filter/jet in the group head.

    Also, that thread did have a handy time/temp graph of filter basket temps when looking at flush times and temp stability during shots.



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