ULKA pump humming and not pumping at times (intermittent) - Page 3

Equipment doesn't work? Troubleshooting? If you're handy, members can help.
JRising

#21: Post by JRising »

havenoclu wrote: So there is a chance that all of these pumps are good and something is not always letting the right amount of power get to the pumps to do their job?
All your pumps seem to be electrically okay, the actual resistance of the coil doesn't matter, the inductive load of the metal inside being drawn through the coil is what counters the "movement of the electrons" in the coil, not actual resistance. But the pumps are stalling, you still hear them hum, they're electrically okay. If you can test them against a known backpressure and prove they're not stalling at less than 11 Bar, then you'll prove the pumps are fine. (I also don't think there's anything preventing power from getting to the pump, your machine is almost certainly electrically fine). As previously discussed, your machine is not relieving pressure at some set point, so by stopping the output from the pump it is physically stopping the pump.

Like a car tied to a tree. You can put it in gear and try to drive but either the wheels will spin (if they can, like the OPV relieving) or the engine will stall. The car's not going anywhere, but there's nothing wrong with the engine.

havenoclu (original poster)

#22: Post by havenoclu (original poster) »

Thanks again for all of the assistance here!

Update: It doesn't look like it was the priming valve, but hey - now it has a brass one! I may take a stab at drawing out how everything is hooked up and post it here to give you more perspective, but I did disassemble the brew solenoid (Parker ZB09, 2-way), and everything looked very clean. I also measured the resistance across the coil and got 237 ohms...which I think should be a positive thing - meaning the coil is ok? It's still a mystery to me as to what could be not letting the pressure release - but maybe it's an intermittent issue with this Parker solenoid coil. The hunt continues..

JRising

#23: Post by JRising »

havenoclu wrote: It's still a mystery to me as to what could be not letting the pressure release - but maybe it's an intermittent issue with this Parker solenoid coil. The hunt continues..
Well, look at the whole circuit. Is there anything in there that WOULD relieve pressure?

The ulka pump has no bypass.

If you look over the entire brew circuit and find any sort of OPV, then you might want to measure the pressure at which it opens, but with your pump so weak that it is stalling, you might not be able to do so without replacing the pump.

If the spring in the three-way valve is supposed to be weak enough to allow the brew valve to function as the expansion valve (picture it, the center port is the inlet from heat exchanger, so the expansion of the water will force the valveface to open and the valve will prevent the fittings from blowing off) then that's just the way that machine was made. The pump is too weak to hit the 15 or 16 bar required to force that valve open so the pump stalls.

So long as it is still able to brew at the pressure you want to brew at, then go ahead and consider the pump to still be okay, but you keep replacing parts and ignoring the fact that your pump is weak enough that it is stalling.

havenoclu (original poster)

#24: Post by havenoclu (original poster) »

I guess I should mention that I've replaced the pump three times. The one currently in the machine is brand new. Let me take a stab at articulating the brew path:

Reservoir -> rubber hose to a plastic T -> one hose coming off the T goes to the pump inlet, the other hose goes to the de-aerator/priming valve outlet. From the de-aerator/priming valve, PTFE tubing goes to a copper T with a Norgren branded solenoid in the path to the top of the boiler - U240315-1353, 110V (boiler fill solenoid?) with the other outlet of the T heading, via copper tubing, to a T on the bottom of the boiler, through a check valve. The other side of the T at the bottom of the boiler is connected via a copper tube to the brew head outlet (I believe after looking at e61 brew head diagrams and the lower orifice being the outlet). The inlet coming off of the brew head is a short copper tube run straight to the top of the boiler.

I realize that may be very hard to follow! Maybe I'll try to draw a diagram. Thanks again for the continued help JRising!

Another thing that befuddles me is that - when the machine is working - I almost always get drips of water coming down the sides of the portafilter during a shot. And this is with a brand new brew head gasket and portafilter basket + cranking down the portafilter. It's almost like there is too much pressure when things are "working".

havenoclu (original poster)

#25: Post by havenoclu (original poster) »

Well, look at the whole circuit. Is there anything in there that WOULD relieve pressure?
I guess no, not really? Only thing would be the solenoid driven exhaust valve maybe?

Nunas
Supporter ♡

#26: Post by Nunas »

havenoclu wrote:<snip>Another thing that befuddles me is that - when the machine is working - I almost always get drips of water coming down the sides of the portafilter during a shot. And this is with a brand new brew head gasket and portafilter basket + cranking down the portafilter. It's almost like there is too much pressure when things are "working".
This is most likely to be a separate issue. Possibly you are not quite turning the portafilter in firmly enough, or when the gasket was replaced it didn't go in correctly, or the new gasket is defective. I doubt it's due to any increase in pressure. I've often marvelled at how the portafilter gasket will not leak at nine or ten bar, even when not firmly twisted into the machine.

JRising

#27: Post by JRising »

havenoclu wrote:
I realize that may be very hard to follow! Maybe I'll try to draw a diagram. Thanks again for the continued help JRising!

Nope, I followed it perfectly... I guess my head is in the zone right now. :)

So your machine has no OPV. The only thing acting as an expansion valve is the three-way that is forced open when expansion exceeds 15 or 16 bar or whatever it may get too... And yes, if your coffee is ground finely, you're brewing at some serious pressures. It sounds like your pumps are fine, your machine is working as intended. It does not have things that other machines have like a bypass or OPV, hopefully it cost less than machines with more.

The one thing that does catch my attention is that your priming valve is feeding the bubbles right back to the pump-inlet... That's either a weird way to take too long to prime the pump, or... Are you the original owner? Is there a chance that someone once replaced an OPV on the pump outlet with that priming valve? There are OPVs that look a bit like priming valves that could be put right there on the nice cool water coming out of the pump, maybe that's what the manufacturer did and someone mistakenly replaced it with a priming valve when they saw its location.

This one is an OPV out of old Saeco machines.

(Yes, I'm really grasping at straws now)

sketcher88

#28: Post by sketcher88 »

For the Ulka EAX5, there's some good rebuild information around, if needed (though unlikely):

https://www.instructables.com/Rebuildin ... so-machin/

In Section 8, there's a discussion on adjusting output pressure, which isn't a pump adjustment on this pump (unlike some bigger pumps), it's on a downstream valve. If you're not getting what you need on the output pressure, I'd suggest you look at the OPV. Call that what you will, there's usually a device on the pump discharge that sets what pressure is enough to get things flowing. If I had my way, it would just be called an adjustable spring check, not an OPV, but that's me just being petty now!

On a different machine I got about a year ago (one with integrated discharge set screw), I received it from the seller with the set screw all backed out, so that rotary pump just recirculated the same fluid from the inlet to the discharge and back. A few turns to increase set pressure did the job. When my seller shipped me the machine, they did their best to fully drain it and fully opened this screw and so I initially didn't think that could be an issue until I thought about it a bit and screwed in, cutting off a recycle loop to the pump inlet which was basically robbing my pump of it's effort.

On a different application with an equally finicky setup, I've had pressure set screws and adjustments move over time, primarily from vibration. That said I'm not 100% sure it's that easy, the OPV might just be stuck open (a spring check with a spring pushing on a ball to close it) and have some debris in it, so it's not quite the same as a set screw drifting but the overriding comment is that the pump might be okay, it might just be that the OPV is stuck open or (and this is worse), it's stuck closed, so there's some potential damage to happen over time. One other thing you might be able to do is disconnect the pump discharge and see if it'll pump into a bowl, or even against your thumb on the discharge, if there's no pressure gauge. if so, the pump might be just fine.

havenoclu (original poster)

#29: Post by havenoclu (original poster) »

Thanks for the continued replies! I think my approach will be as follows:

1) Measure the pressure at the brew head by modifying a backflush disk with a pressure gauge. I've wanted to do this anyway.

2) Remove the priming valve and add an OPV (unless anyone thinks I should keep the priming valve with the OPV. If there is a diagram on how to properly introduce an OPV after the pump, that would be excellent!

Thanks again

havenoclu (original poster)

#30: Post by havenoclu (original poster) »

Alright, here's an update: The portafilter with pressure gauge showed around 14 bar - maybe a little above. I guess an OPV could take this down to 9 bar, which would be ideal but would this solve:

1) Water escaping between the portafilter and gasket during brewing? I'm guessing probably not, but I can't quite explain it. The gasket appears to be seated properly and I CRANK the portafilter down - to the point where it is very difficult to remove after pulling a shot. It's overkill and nothing like my old Gaggia Classic.

2) The pressure build up that stalls the pump out?

If not, I'm not sure how to proceed and I might have to find something else. This has definitely been a labor of love, but the love part is waning quickly (or has waned?). I just want awesome espresso every time!