Hello,
I have Bezzera Unica almost two years now (i always use resin filter and one week ago i cleaned it with durgol - decalcifier).
However, today i noticed a really strange behavior:
https://drive.google.com/file/d/0B6-5FQ ... sp=sharing

does anyone know what the problem could be? and if i can, how to fix it?

I'm not sure, but maybe a small chip of lime got loose by your decalcifying of last week and is now hindering the pump.
I would try and decalcify the machine some more and see if that helps.

This is usually caused by a piece of grit in the OPV (overpressure valve). Unscrew the part with the hose back to the tank, clean off the seal and screw it back in.

If the problem persists, it's usually bad news -- the seals inside the pump are failing and the pump needs to be replaced. You can try disassembling and cleaning the pump, but that mostly doesn't work.

There are posts on HB that give pictures and instructions, use the site-google option in the search function to find them.

Lots of possibilities:

Descaling the machine may very well have left some obstructing debris in the grouphead . . . see this:
Checking an E61 Espresso Machine for Scale

Is this Unica fitted with the factory PID? Do the pump pressure fluctuations coincide with power application to the heating element? While it would be unusually coincidental, it seems as though the pump is losing voltage. Depending upon your mechanical/electrical capability, this would be easy to confirm.

In addition, I would adjust the OPV such that the maximum pressure on your brew pressure gage is 9.0 bar while pulling a shot.

so the technical man called me the told me he wants to replace the pump and one of the valve.
he said it is going to cost around 368 USD which is a lot for me (around 25% of the original value of the machine). = the machine is just two years old so it is kind of weird that i should already change the pump, moreover, he said the pump is working, it is just weak.
so i've decided to take the machine back and to try to fix it myself.
thus, i have some questions:
1. descaling again might solve the problem? if it might, which solution should i use?
2. can you address me to a guide for cleaning the OPV or even the way to adjust it?
3. if i need to change the pump, can i just order one through the internet and do it myself? i mean, is it really complex that even if i will be really careful i won't succeed?

thanks a lot...
if you more things that you think i should consider let me know...

erics:
no, the pump is it coincide with the power application.

another_jim:
where the opv is? how should i clean it?
any info would be great

thanks again!!!!

hutorihunzu wrote:another_jim:
where the opv is? how should i clean it?
any info would be great!

another_jim wrote:There are posts on HB that give pictures and instructions, use the site-google option in the search function to find them.

some updates:
i opened the machine:
https://drive.google.com/file/d/0B6-5FQ ... sp=sharing

we took of the problematic part :

https://drive.google.com/file/d/0B6-5FQ ... sp=sharing

and here is the pump:

https://drive.google.com/file/d/0B6-5FQ ... sp=sharing

so now i have a few more question:
1. in this picture:
https://drive.google.com/file/d/0B6-5FQ ... sp=sharing
which one is the opv and which one is the check value?
while operating the machine we saw water coming from the right part (the one make of akulon ) going back to the reservoir tank and also this part has a Spring. moreover here is the manual of bezzera:
http://i62.tinypic.com/2e307eb.jpg
the left part is number 1 while the right part is number 16.

2. we cleaned those parts and put them back and it still didn't work. do you think that just after two years of using the valves can be pulverized?

3. the problem might be in the headgroup? maybe a lot of Limescale in it?

and in general what should i do next? should i order all those parts and pray it will be solved or should i just start from the akulon part (this specific part is what the technical man said to be the problem) and order one and replace it? (by the way there is the same part just made of Brass??)

thanks a lot!!!!

See below -



Two years would seem a short time but a lot depends upon usage, water quality, etc., etc. Disconnect one of the wires to the heating element and operate the pump with a blind filter in place. Adjust the OPV such that the gage reads 9.0 bar. Does the machine still exhibit the pulsating pressure behavior ?

I would also suggest (as previously) that you check the grouphead for scale.

The nylon hoses from the pump priming valve (your Akulon) and the OPV are joined with a "Y" prior to their return to the reservoir. If you run separate hoses, there should be NO FLOW from the priming valve at brew pressures and certainly some flow from the OPV.

ok, so i checked the grouphead there was little scale, i cleaned it but it didn't helped.
i've checked another thing, i turn on the pump mode (which is used to pour hot water, it is done by turning only the pump to fill the bolier) and i saw the pressure goes to 10 (usually the pressure should be 13) and then silence until i release some water and then i pump turning on again.
thus, i suspect it might be the OPV.
anyway i will try and disassemble the OPV and adjust it + i will check the flow from the OPV and from the Priming valve
some more questions:
1. how comes that this thing has changed? i didn't do anything special so how it is possible that the OPV changed so dramatically (or is it the pump which is weak?)
2. i saw this pic that you posted and i wonder, why the plastic valve does not run water to the reservoir at brewing level?




3. and just for me to know, if the priming valve is faulty what should i see? i mean i guess it's purpose is to maintain the water until it goes to specific pressure, but what should happen if i would disconnect it the turn on the machine?
thanks a lot!!! i am so glad that you are helping me!!!

But you are not doing what I asked and that is to:

Disconnect one of the wires to the heating element and operate the pump with a blind filter in place. Adjust the OPV such that the gage reads 9.0 bar.

. . . i wonder, why the plastic valve does not run water to the reservoir at brewing level?

Because it is designed to close at a pressure of 6 to 8 bar.