Hey all,

I wondered if anyone can help me fix my coffee machine.

Recently my coffee machine water flow has slowed down. I figured it must be the pump as I could hear it buzzing differently. The water flow was almost non existent, it would still brew a coffee, but getting to the right pressure would take considerably longer, and had to dial down the grind.

Anyway, I bought a new pump as old one was 13 years old and replaced it, but nothing has changed.

Now I'm trying to figure out whats wrong. Steamer works fine, as well as the hot water through the steamer (for making T), so the pump is doing its job, but no water comes out through the head group (or whatever is this called). I thought it could be a block but I can see the water flowing through the tubes (when using steamer for T). Thinking now if I should disassemble the head group and see whats inside, but this is gonna be bit awkward, so thought perhaps someone knows what else I could do before doing that.

Any thoughts?

Happy to post some pictures to show what's going on, but all I know, if I press the button for constant water flow through steamer (for making the T), but close the steamer valve - the pump makes the same noise as when trying to brew coffee (slightly different sound as the flow is closed, but the pump is pushing it), but no water comes out when trying to brew the coffee, so it kind of sounds like blockage.

This machine was periodically descaled and cleaned (thought every time I would not find any bits of scale in the waste water...)

Cheers.


M

Do you know if that machine has a 3-way solenoid for a brew valve? (Ie. you can back flush it and it drains excess pressure to the drip tray when it's done brewing). Or is the brew valve just a rubber plug on a spring in the dispersion screw behind the shower filter?
Chances are that that's where the blockage is.

You cay you see water moving in the tubes, so where is the water going? Is the pump moving the water, but the blockage is forcing it to all escape over the OPV and flow back to reservoir through a return hose? If so, does opening the steam valve allow it to all flow out the steam wand?
With the steam valve open, can you block the water from flowing through the wand with your thumb over the steam tip? You can easily block up to about 4 or 5 bar with your thumb. It's really hard to block more than 10 bar with your thumb (just a guide for those who don't have a means to measure fluid pressure but want to).

So: If your pressure is fine, can flow from wand but can't flow from head, clean the blockage out of your brew-valve.
If your pressure is pathetic and you can stall the pump with your thumb over the steam tip (no flow over OPV), replace the pump.
If your pressure is pathetic and it flows fully over the OPV with your thumb over the steam tip, your OPV is stuck open.

Hey JRising,

Thanks for replying.

I will post some pictures tomorrow, as its late on my end right now, but there is some 3 way valve mounted into the boiler (I think, or could be the one connected to the steam wand?),
I can see the water moving when I open the steam wand, otherwise its pretty static (as the circuit is closed/blocked)
This is how I figured the pump I installed works - hey!

Tbh it was the first time I opened this coffee machine (had it for around 10 years now - and this is the 1st coffee machine I opened).
I'm not familiar with the types of valve, but if you (once I'll post some pictures) could point out which one is the one you think I should try cleaning/removing I'd very much appreciate that

No water is being pushed via the back hose to the reservoir (there is a hose going down to the waste drawer at the back).

I will try the thumb tricks tomorrow, and will come back with some pictures, and a video if that helps

Whats OPV?

Regards,
Michal

Hello Michal

there's no OPV (over pressure valve) and no 3 way solenoid valve. This is a kind of Rossi type group. I don't think the problem is about electricity. Did you descale the machine?

Hey all,

I didn't descale the machine, done it not too long ago, but not since I noticed the problem 2-3 weeks ago.

Below I recorded video of the issue and one showing what happens when I hold the button for hot water via steam wand (which seem fine)
Please don't have a go at me for the dirty steam wand








Any thoughts?

Regards,
M

Mik8282 wrote:Hey JRising,
Whats OPV?

OPV is over pressure valve.
La Pavoni Domus Bar is "modified clone" of Lelit Anita. Anita have OPV, so I expect OPV also in your machine.
This video may be useful:

Okay... So there's the machine in pictures.

I'm going to assume that it's clogged somewhere. If you have thoroughly cleaned everything in the grouphead (shower screen, dispersion disk, etc), then I still suspect the clog is in the three-way solenoid brew valve... It's in the picture, so I expect it is working but partially blocked. Perhaps descaling will help, that's a fragile little machine that will as happily break fittings off rather than let them be re-used.



And again, there's your OPV in the picture (Over Pressure Valve). It limits the maximum pressure that can be contained in the circuit by relieving some when pressure forces it open. Again, those OPVs are cheap little things, I would have the replacement in hand before trying to adjust it because those prefer to disintigrate rather than adjust nicely.

Hey Jrising,
Many thanks again for all your wise words.

I will try descaling and see what happens.

I was trying to figure out which way the water is supplied to te group head.
Am I correct saying this goes via that solenoid valve through the tube going up directly to the group head?
If so, how does this thing withstands all that pressure (with this small rubber tube )?
I'm just curious here as I thought that main supply.of water when brewing coffee goes via that OPV valve and it may be blocked at the place where it connects to the group head, and thats why it goes kind of in circle (joining back the circuit via the Y shape rubber tube) , and its where I first wanted to check - by removing the group head and opening it.
I also wanted to give it a good clean once opened.
Anyway, I'll try descaling first, but idk why since I opened it I have a weird urge to disassemble some of this parts and check for limescale (main focus being on group head)
For some time I had a feeling that the steam nozzle doesn't produce as much steam as it used to so I often struggle with latte or cappuccino, but I blamed my milk frothing skills.
Thanks again
M

Hey, I have a ekhm small update on this thread.

It is a bit weird one, but today I figured that first advise here usually is to descale the machine.
I prepared the solution using not 1 but 2 tablets for stronger solution.
I dissolved the tablets, and started the flush via steam wand.
After maybe 20 seconds, I closed the steam valve, then thought I'll do the same for brewing coffee cycle (not really expecting anything but to get the descaling solution as far as it can get).
Then bam, to my surprise water started flowing through the group head like there was no issue...
Would the descaling solution do such a good job straight away ?
Anyway, I will do a 'deep' cleaning over whole day - moving the solution every hour or 2 to flush it properly and later on will check how is the pressure when trying to brew the coffee (fingers crossed).

Thanks all for your help, I will send an update once I check the outcome

Regards,
M

Hey all, thought I'll post an update, after descaling twice it seems that all is good.
Thanks for all your help, I will try descaling more often to avoid this kind of stuff in the future.

BTW, is it safe to descale with clear vinegar undiluted ? I do this to my kettle every now and then and undiluted vinegar does the job in minutes, I understand that because of rubber tubes in washing machine this may not be advised, but I was thinking to basically do that over 15-20 minutes with eg.half litre of vinegar, and then flush it all with water thorougly.


Regards,
M