JohnB. wrote:Bingo!! What could be easier?

Can't argue with that.

Next question is what should I be watching for and how should I be adjusting to make sure that I have proper adjustment.

By closing the expansion valve (clockwise) I'm essentially allowing a higher Bar of pressure to be reached, so I should be able to completely close the valve when the machine is off, then as it is heating up, adjust it open, as it reaches ~12bar and continue to ensure that it does not exceed this.

If I see that the pressure never goes about 9, with the valve completely closed, one could assume: Faulty Expansion Valve. Correct?

Just making sure I have my thinking correct, I appreciate everyones help, and I apologize for the ignorance.

allon wrote:If the expansion valve exhausts into the drip tray, you could run the pump against a blind basket a la backflush; if the expansion valve doesn't drip, then it isn't limiting the pump pressure.

This assuming the pump limit is set higher than the expansion valve, correct?

I wouldn't get hung up on the 12 bar setting as that is your upper range. I have mine set so that it seals shut just over 11 bar but anywhere between 10.5-12b is fine. Mine adjusts with an allen wrench & a small tweak can move you 1 bar so don't go overboard tightening it up. Also do not expect to see the machine idling at your chosen setting every time you check on it.

I agree, I'm not worried about the 12bar but what I'm worried about though is if the expansion valve is set lower, it could be inadvertently lowering my brew pressure due to the max pressure correct? Or is this something that I would see when brewing/looking at the gauge? I do know that as set at ~9bar my rotary pump is a bit high pitched, if I crank it down, to like 8, the noise starts to dissipate, not completely but its less annoying.

So i'm really just trying to figure out the best way to test the expansion valve, get the pressure in the boiler higher than ~9bar so I know the expansion valve is working, and limiting correctly, then adjust my brew pressure to ensure that it is not being limited by the expansion valve. The noise is separate issue... well, it may be.

From Page 22 of the Linea Maintenance Manual:

CHECK EXPANSION VALVE - Run 1 liter of water from groups by activating brew switches. This should cool the brewing boiler slightly. As the water reheats it will expand, thus creating excess pressure. At or near 10 bar the expansion valve should begin to relieve this pressure. The expansion valve should open to prevent the pressure rising above 12 bar. Adjust or replace expansion valve as necessary.

I'm trying to think whether there is any downside to simply jacking up the pump pressure to a high value (obviously above 9.0 bar) with a blind basket in place but nothing comes quickly to mind. Adjust the expansion value such that you get some drips under this condition and then reset the pump to your chosen brew pressure.

The LM procedure obviously tests the valve under the conditions at which it is designed to operate so this could be a very valid "double check".

erics wrote:From Page 22 of the Linea Maintenance Manual:

I'm trying to think whether there is any downside to simply jacking up the pump pressure to a high value (obviously above 9.0 bar) with a blind basket in place but nothing comes quickly to mind. Adjust the expansion value such that you get some drips under this condition and then reset the pump to your chosen brew pressure.

The LM procedure obviously tests the valve under the conditions at which it is designed to operate so this could be a very valid "double check".

Thanks, Eric. I must have overlooked that, I was reading through all of the manuals and I guess I missed that part. I'll give this a shot tonight when I get home.

erics wrote:From Page 22 of the Linea Maintenance Manual:

I'm trying to think whether there is any downside to simply jacking up the pump pressure to a high value (obviously above 9.0 bar) with a blind basket in place but nothing comes quickly to mind. Adjust the expansion value such that you get some drips under this condition and then reset the pump to your chosen brew pressure.

The LM procedure obviously tests the valve under the conditions at which it is designed to operate so this could be a very valid "double check".

Eric,
So I basically did what you said:

First thing I did was your double check test, I did this first because I wanted to make sure the expansion valve was in range first, and not low.

I put in my blind basket, pulled the shot, adjusted the pump up around ~11bar, I noticed the water was running through the expansion valve freely, so I tightened it up to a "Drip per second" and then relieved the pump pressure back to ~9bar, the dripping stopped.

I then flushed the system of 4 cups of water, which dropped the temp (according to the PID) to around 180F, it then rose back to 200 where I currently have it set. During this time the gauge fluctuated a small amount, got up "maybe" to 10bar, but this is the first time I've actually noticed it rise that high, so thats a plus.

So now I feel confident I have things where I want them, so to speak.

Next question, which may or may not be related is the sound of the rotary pump. I've attached a video I took this evening, hopefully it clearly resonates the sound. Can anyone tell me if this high pitch, is typical of rotary pumps? I only ask, because while I was adjusting the pump and the expansion valve, I was actually able to get this pitch to stop, and the only sound that was audible was the vibration of the pump. Im not sure if this is a good thing or not.

Sounds like a table saw that has a motor with bad bearings running next to a jackhammer! Hopefully most of that was the way it was miked but something isn't right there. The quiet vibration sound you described is closer to normal.

Yeah, I never thought to ask anyone, because I heard rotary pumps could be really noisy. I had the pump rebuilt professionally by JC Beverage when I was restoring the machine. I've been doing some more research and found someone saying the expansion valve and pump should be adjusted in tandem, but I'm not sure if that noise has anything to do with this or if it's just a pump issue.

The jackhammer sound is just the fact that I have no foam or feet under it, so it vibrates on the ground. The high pitch noise is really the issue that I have.

That noise would drive me nuts. Adjusting the expansion valve changes the portion of the pump flow going into the system (obviously) and hence the change in noise. What is the noise level when pulling a shot or filling the steam boiler? What is the complete nameplate data on the pump; what is its pedigree?

I realize the motor is resiliently mounted at both bearings with a sorta rubber "surround" but the clamping arrangement for same looks a little strange - just going by memory. Likewise on the clamp arrangement holding the pump to the motor - perhaps a little less so.

The inlet for the pump should not be such an abrupt 90 ell but rather a smooth radius bend even though the flow is relatively low as compared to the pump's capacity. Likewise the discharge hose should have a support of sorts to avoid being self supporting. The motor/pump assembly itself should also be resiliently mounted to a solid structure.