Hi,

I descaled my Expobar Office Lever (HX machine with vibe pump) yesterday and the pump seems very sluggish now. Ran durgol through the group as well as boiler. Everything seemed fine, I did a backflush as well and no issues. This morning the pump is having issues getting past 5 bars.

Tank pressure is solid at 1.1 bar.


Here's the symptoms I'm having:

Before descaling:
Pressure gauge goes to 10 bar (supposedly means 9 at the grouphead).
When using a backflush insert the pump will work really hard and start to squeal if left on long enough (stays at 10 bar also).

After descaling:
Using backflush insert again the pump sounds normal to 5 bar and return line is pumping out water.
At the 5 bar mark, the pump goes really quiet and the return line stops returning water, it very slowly gets to 10 bar but there is not longer any struggling of the pump just a faint hum. When I stop the shot, the OPV sprays water into the drip tray like it should but the pressure gauge stays at 10 bar. When I pull the lever again the pressure drops back to 0 and the return line sends water back into the reservoir and the process starts again.


Any ideas? Should I descale again? Is this problem on the HX/group side - should I just descale that portion and skip descaling the boiler?

Thanks,
Mike

Often the descale cleans and loosens up the OPV. Try tightening it up util you hit 9 par again.

Thanks I'll adjust the OPV and see what that does.

Maybe I'm missing something here but it seems like my OPV is working backwards?
Water is flowing to the return line at < 5 bar. (OPV is open?)
Water stops flowing from the return line > 5 bar - the pump get real quiet at this point but it slowly inches to 10 bar.

If the OPV was too loose, wouldn't water the water return flow at < 5 bar instead of stopping?

I can't explain what you are decribing. OPV's should only open when the pressure is above their setting.

Thanks.

I ran some descaler through again just in case there was some dislodged scale mucking things up.

I played with the OPV but here's what I'm getting:

OPV at original setting: Gauge maxes out at 8 bar (but slows and pump is quiet after 5 bar). Once I stop the pump and the 3 way valve releases the excess, the pressure gauge starts to climb to 10 bar and holds. I can adjust the OPV and the slightest turn will adjust the pressure gauge's needle either direction.

When the pump is on and finally gets to 8 bar - I can do several turns of the OPV screw and it gets to 10 bar. Once I stop the pump, the pressure increases to about 13 bar.

The pump always squeaked and groaned when after a few seconds of max pressure when backflushing - the pump just gets quiet now. So this makes me doubt the gauge is having a problem.

Your pump has probably experienced heat death. Did you pump hot water, or leave it on too long without giving it a chance to cool, two common mistakes when descaling?

Most vibe pumps are rated for 1 minute on 1 minute off, or in some cases (like the 52W ulka's) 1 minute on 1.5 minute off. And that is for 25C water. There is no official rating for hotter than 25C water like what will be in your espresso machine tank, but I try to avoid running for much more than 30 seconds, and leave it off for at least as long as it was on.

When descaling, let your descaling solution cool before using, and be mindful of how long your pump has run.

On the upside, pumps aren't that expensive and are fairly easy to replace.

While I didn't run any hot liquid through the pump, I definitely ran it beyond the 1 min on / 1 min off spec.

I took the pump apart looking for any descaling debris and it looked fine.

I couldn't find any instructions online for replacing the pump. I'm not sure how the pump's brass fitting connects to the OPV it doesn't look like a threaded or compression connection. It looked like they are just screwed together with some red paste (Loctite?) at the connection.

Thanks

Loctite is not food grade, I just use teflon plumbers tape when I need to make a seal. I've only personally done the pump swap on a quickmill anita, hopefully the place you bought from can give you any pointers you need specific to your machine, but from my experience it really is as simple as unhooking everything connecting to the old pump and putting the new one in its place. The only tricky bit is priming the new pump, you need to force some water into it to initially get it going. One of those ear syringe bulb things works well for this, force some water into it when you first turn it on and then quickly drop the intake line into the tank.

Thanks for the advice on priming the pump - I probably would have missed that step!

I looked at the connection again this morning and I can see two locations for a hex wrench to unscrew them - not nuts but a location to grab onto. It should be obvious once I get the replacement pump.

I ordered the same pump and teflon tape from amazon so I can try tomorrow. I already ordered some food grade loctite from grainger - when I looked at the connection it definitely had some sort of colored paste applied. You're right it's probably not needed - I figured it would help with the constant vibration. I'm learning here.