Welcome to CS, cant help with your question but it will get answered soon enough. GREAT looking machine there though !
I purchased an old BZ40E (built 1996) some weeks ago.
After complete dismantling, cleaning and some repair its working fine now, but Im still trying for better results.
Is anybody here actually owing a BZ40 or has some experience with that machine?
Welcome to CS, cant help with your question but it will get answered soon enough. GREAT looking machine there though !
nice work stefan.
apart from the steam arm, looks brand new.
what kind of help were you after? perhaps non bezzy owners can help out?
Bz 40 is a great machine we usually sell this machines for offices.
It has 2 x 1450 Watt elements and a 3.4L boiler, rotary pump and the new ones come with bold join steam arm. In conclusion what you have in your home I will put it in an office any time.
If you need any help let us know, I was trained by Bezzera in Australia.
Hello and thanks for yr answers!
What Im still puzzled about is the heat exchanger, which is of the small type (abt. 16 cms) like in BZ99 or BZ35.
I got the information (from a serviceman), that these ones were installed in older series of the BZ40s but Im not sure if thats true (Can somebody confirm that???).
In fact, I found the boiler a little bit bent outside at the ends, most probably by former frost damage. So, a long HX wouldnt have fit (conflicting with the center pipe for the level probes). My suspect is, that a serviceman had installed that small HX as a compromise solution to avoid installing a new boiler.
I adjusted the boiler carefully with a car jack (which went pretty easy) and ordered a long HX.
Although the machine is working quite satisfactory, I sometimes have the impression that the brewing temp. could be slightly higher.
(What I get in my cup has abt. 60°-65°C depending on the flowrate).
I found an old thread on the same topic (http://coffeesnobs.com.au/YaBB.pl?num=1121576985/0) but I wonder why that short HX shouldnt work properly in a BZ40 if its doing well in the BZ99 and BZ35.
The nozzle at the outlet of the HX is the same part in BZ40 as in BZ40 thus having the same diametre.
The boiler temperature is the same in all machines and the flow rate as well.
So I cant really see the necessity for different HXs in those machines.
Can anybody help?
OK, after installing a the HX everything is working fine.
Temperature in the cup is 68-72°C which is quite optimal I think.
Yes I have this machine which I rebuilt completely. You "adjusted" your boiler with a car jack? :o The boiler is designed to be curved at the ends to strengthen it against internal pressure, you should NOT bend the boiler. I really hope I have misunderstood what you have written because if the boiler has been deformed either intentionally or unintentionally (through freezing) it may not have the strength it was designed for. When boilers are built they are pressure tested and certified as safe. I am not sure what the design certification is for espresso boilers, but somebody else may be able to help. At a guess I would say 3 bar. The BZ-40E is fitted with a 1.5 Bar pressure relief valve. If the strength of the boiler has been compromised it is possible the boiler will fail. I was hoping to find a picture of an espresso machine where the boiler has exploded but cannot find one handy. While the -40s boiler is "only" 3.7l I can assure you, you would not want to be around this machine if the boiler explodes.
Can you please clarify if i have misunderstood and possibly post any pictures of your "adjustments"?
Stepfan,Originally Posted by CaptHaddock link=1231353551/0#4 date=1231424038
The HX is designed for a specific machine.... the temperature of the resultant brew water is dependent on the diameter of the pipe.... the length of the pipe, the percentage in water as opposed to steam, the flow rate.... and a whole pile of other factors beyond my understanding.
A skilled thermal engineer (a rare breed of person) has designed it to work properly - that unit in that model machine..... and changing it in any way will affect the outcome.
So the brief answer is if you change any of these it will affect your brew temp (and the reason for this may not be immediately apparent).
Also deforming a boiler, even if only to supposedly restore it to the correct shape is a no no.... It is a pressure vessel (as Pete said above) and deforming it could well have reduced its ability to hold pressure. Failure wont be immediate.... but at some time in the future it might decide 1.5Bar is too much - and fail (even more likely if the pressure relief valve doesnt operate properly).
Good luck with your machine. Whilst disassembly, descaling, reassembly etc is within the scope of the home "mechanic" - repairing damage or modifying bits is something we shouldnt do IMHO. A boiler is a VERY dangerous device and should be treated with respect.
I think its worth reminding others that may lurk just how powerful steam is. I have an interest in simple machining (which I am woefully incompetent at I may add) and, while I have no interest in model steam engines, read related magazines as they often provide excellent articles to new "machinists" (and I use that term generously in my case). While the steam pressures they use may be considerably higher than an espresso machine, the power of these little model steam engines has to be seen to be believed. I have seen pictures of espresso machines where the boiler has exploded and it is quite unbelievable the power, it literally looks like a bomb has gone off. The bottom line is, dont screw with your pressure relief valve and if your boiler is damaged you have it tested or replace it. No ifs or buts about it.
Personally if i faced that situation I would try to contact the local model steam enthusiast club. I know model boilers are tested and the members there may be able to test the espresso boiler for no cost to help out an enthusiast.
Thanks a lot for your advice/warnings regarding my "boiler adjustment".
I add two pictures, first one is the boiler in the original state.
The slightly curved end is definetely not designed to be like that (I know it because I already have a new one here which is totally flat).
On the lower picture you can see the boiler after adjustment. I didnt push more than 3 mm (!) and I pushed very very smooth.
My idea was to keep that new boiler as a spare until next maintenance.
Maybe I will fit it soon but I really havent the impression that the old boiler has suffered any damage (That copper is so soft, you can nearly bend it with your thumb).
We dont generally have the issues of freezing boilers to contend with here in Australia and my BZ-40E has an identically curved boiler to your "before" photo. Judging by the condition of the machine when I received it and from what I know about boilers I believe mine is completely original and undamaged.
The area of weakness I would be concerned with is the welded seam between the boiler side walls and the end plate itself. They are already the weak point and would have been heavily stressed during the "adjustment" process. Its possible it MAY still be fine, but who knows? It will need to be tested or replaced Im afraid.
Its quite possible Bezzera dropped the curved end plate with the replacement versions and either decided it was unnecessary or constructed it from heavier gauge material. Flat faces on pressure vessels are typically avoided as they are weaker than curved faces, this will require thicker material for the same strength. This may be more expensive but would need to be factored into the cost of manufacturing the curved face to begin with.
You also asked about the heat exchanger, although its partially obscured in the photo, it appears to be the correct BZ-40 part.
Incidentally, it looks as if youre using a metal gasket to seal the HX. If you have trouble with this sealing there is a better white one available made from some form of plastic (ptfe??) that requires less torque to get a good seal.
at least you made me nervous, so I decided to replace the boiler (1st picture with new one installed).
But, there are some things that are still a bit strange. From the beginning on:
The first thing, that happened to me was, that the lower heating element was destroyed when I unscrewed it (when I initially started to overhaul the machine). That was due to the fact, that the boiler end was bent outside so that the HX and the heating element werent parallel but touched at the ends. So the heating element couldnt turn free, was blocked and destroyed!
So I think that although a slight curve maybe OK like in your machine, my old boiler was definetely more deformed than it should be.
As you can see from the second picture, there is a pipe inside the (old) boiler, protecting the level probes. I think this pipe was dismissed, when Bezzera changed the HX-design to the long version (my new boiler doesnt have it any more). Maybe there had been more occurencies where the new HXs came in trouble with that pipe when the boilers were slightly bent.
In the last picture you can see the old HX and the new one.
Which one is fitted in your machine?
The last item is, that I noticed that the new boiler, which was completey flat (even 1mm or so *bent inside!) in the beginning, after first commissioning came outside a little bit (maybe also 1 mm).
Maybe its normal with those Bezzera boilers, that they bend out a little after years of service!?
best regards Stefan
Hi Stefan, its possible that if the boiler was frozen the curve on the end was increased and has caused you problems. Im afraid I cant offer much of an opinion here as most of Australia has a very mild climate. Its also possible, as you mentioned, that the end plates are flat to begin with and curve out with use, however Ill be honest I doubt it. Both ends of my boiler have a definite radius and I believe they were designed that way. I think the point is that youre entering ?????land. Maybe it was designed that way? Maybe it expands on use? Maybe? Maybe? Unfortunately with something like a boiler I dont think its worth any "maybes", if its been deliberately bent or has frozen its trashed so I dont think youve wasted your money there. Its one of the hardest things to do, to throw away something that "looks ok", but is really a giant ??? The manufacturer or good agent are probably the people to speak to with this type of thing, maybe the boiler end plates do curve with use and can foul the elements.
Anyway, as far as the HX, I believe the top one is from a BZ-35 and the bottom one is from a BZ-40. Having said that I dont want to pretend Im any sort of Bezzera expert, its been a while since I had my HX out *and the only difference is length. If you measure both and send a message to Jack at Barazi http://www.barazi.com.au/Contact-Us/Barazi-Bezzera-Coffee-Machines Jack will be able to tell you which is the correct one for your machine. If you dont hear back within a couple of days send me a PM and Ill give you his email, just dont want to post it here due spamming. Im pretty sure the BZ-40 HX reaches almost to the bottom of the boiler, but this is interesting, as this is the second -40 Ive heard of where somebody has swapped the HX, and Im buggered if I know why as it completely changes the machine!! The -40 doesnt need much of a cooling flush (like most Bezzeras), to flush mine I push the double dosing button once and thats it.
Incidentally, nice job to get the boiler exchanged so quickly. How are you going getting the Serto fittings to seal again? They are surely the work of the devil in my opinion, sent upon us to test our collective patience *:) There is a trick to getting a good seal using Loctite in the correct places so if you have trouble with them let me know. On the other hand if youre always able to get a good seal first time let ME know as Id appreciate any tips on those rotters.
Good luck with the rest and let us know how youre getting on.
PS I am just in the process of replacing the pump in mine, wow what a difference. Unfortunately one of my delightful Sertos was leaking (surprise surprise) so I basically have to pull half the machine apart to clean them all and reapply the Loctite. Grrrr
thanks for advice abt. the HX but there is no doubt that the long version is the correct one. A Bezzera serviceman gave me the information that in old BZ40s the short version was used until they changed the design to the long one.
About those Serto Seals: Which seals did you have problems with? The tapered screwed connections on the boiler itself or those smaller screwed joints which we have for example on the pump or at the drain pipes underneath the boiler (with the flat sealing surface)?
Fortunately I had no such problems up to now.
Why are you replacing your pump? Is pressure too low?
I was considering an exchange as well because the pressure didnt raise more than 8,5-9 bars with fully closed pump bypass.
Then I dismantled the pumps bypass valve and found some corrosion on that small backflow valve inside which obviously caused a constant baypass flow. After cleaning and grinding of the valve seat the pressure of my pump increased to 10-10,5 bars which I find is OK.
Oh sorry, I thought that was your question.Originally Posted by 303D3136352D3D3B33580 link=1231353551/13#13 date=1231917427
I have trouble with the small (12mm) Serto fittings. They seem to always leak back up behind the nut and looking at the design its no wonder as they seem to rely just on the flat face for a good seal. Normally that isnt a major problem as you can apply thread sealer behind the nut before assembly however there is one thats on the pump outlet where that isnt possible and, of course, I cant get that one to stop leaking. This morning I spent some time making sure it was perfectly clean and straight before I assembled it, so now I will pull it apart yet again.
My pump had similar symptoms to yours but no amount of tinkering could fix it. It really did seem to be past its used by date. It seems to be the original so no surprise there. The new one is very good, stable pressure and easy to adjust.
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