Hello all,

Long-time lurker, first-time poster. Forgive me if this question has been asked and I missed it in my review.

I direct plumbed my Linea Mini last night and was getting proper brew head pressure on the first couple shots I pulled:

3 bars with the PF engaged
~1.5b briefly during preinfusion
Sharp spike to 9-11b during extraction

I gave the head a good cleaning, including removing and cleaning the diffuser screen, but I'm quite certain I didn't overtighten when returning it.

This morning my brew head pressure was low. I pulled four shots, each of which went approximately:

3b with the PF engaged
~1b for a while during preinfusion
Slow build to 6b during extraction

I tightened the brew head pressure nut behind the drip tray and got the same result. Here's an extraction video: The strange thing is, the flow through is much faster than pre-plumb. I pull 20g shots (40g output) and usually have an extraction time in the low 30s range, but my extraction time here was ~15s. I'm also getting weaker flow through when engaging the paddle and letting hot water flow through.

If anyone has had this problem before or can suggest where to start for troubleshooting, I would appreciate it!

Look on page 11 and 12 on your owners manual to adjust the pressure and expansion valve.

None of the behavior you are describing sounds normal, you should not have to adjust anything after plumb, if anything you would need to reduce pump pressure to not go over 9bar(which is done in the pump itself, not behind the drip tray). I would certainly not have started messing with the expansion valve.

I can say with a high degree of certainty that your water flow rate is not magically higher now through the group, your flow rate is dictated by the flow restrictor in the boiler and the amount of pressure pushing through that .8mm jet, it's not possible to suddenly have a great increase in flow without changing that or without MASSIVELY higher pressure.

What is your incoming water pressure, what is the full setup from wall to machine? What fittings, what size, what size lines, what filter (s) please post a full end to end description.

It aost sounds like there is a restriction or blockage, did you flush out the setup before connecting to the Linea?

You should have your expansion valve (under the drip tray) set at 12b, your line pressure at 3b from your filter. You then need to take off the housing on your machine like you did when you plumbed it and adjust the pump pressure just below 9b. The key is to adjust brew pressure at the pump, not the expansion valve or line pressure. Fill your portafilter with coffee, start an extraction and adjust the pressure up to 9b while pulling a shot with a puck. You should be good to go after that.

Hmm, that definitely doesn't look right. I'm not direct plumbed, but you should definitely be seeing higher pressure.

Is there any chance your incoming line is restricted, or perhaps some bit of contaminant is blocking things? Sometimes the pipes aren't clean and some junk clogs up things. If the water flow is restricted, you won't reach full pressure.

Machine sounds funny too, but very hard to judge on a youtube.

Thanks for the feedback, all. I spoke with the La Marzocco Home customer service line yesterday, and have the tech who sold me the Linea Mini coming by Thursday to take a look at it. I'll post back here if/when we get this issue sorted out.

@sluflyer06: My ambient water pressure (i.e., the pressure from the plumb feed) is between 3 and 3.5 bars. My setup from wall to machine is a 1/2" PEX line, which is run into a 1/2"-to-3/8" T-split valve. The T-split feeds my kitchen sink faucet and the LM via the 3/8" line that came with the official plumb kit. I'm not running the faucet and the LM at the same time, so I can't imagine the split is having any impact on my water flow or pressure. (I don't use a filter -- both the La Marzocco tech and I have tested the water and it's exactly where it should be for the Linea Mini. All the plumbing in my house is also PEX.)

On the pressure adjustment tip, the LM rep explained that the adjustable nut behind the drip tray only changes the expansion valve's output and won't change what I see on the pressure gauge. He made the same comment as sluflyer06 that, if anything, I should be seeing a spike in pressure following the direct plumb.

I agree that there has to be a restriction or blockage somewhere, but I can't imagine it's in the plumbing from the water line to the LM since that's simply a T-split and the LM plumb kit line. Hopefully the La Marzocco tech can provide some insight. Thanks again!

I'll preface my remarks by saying I don't own a LMLM but do have a plumbed in machine.

I seem to notice that there are at least 2-things that strike me as odd. The main one is that as soon as the pump is engaged the water pressure level seems to drop below static line level pressure. I never see that at home except when our washing machine is filling, as they share the same line. This also gives me the opportunity to experiment with preinfusion at a significantly reduced line level pressure but this should not happen in your case. Your pump pressure gauge should be sensitive to and register any change of water pressure in your house but not drop as soon as the pump engages.

The other thing is that either your grind and/or dose is off in that there seems to be too much flow and blonding too early. The pump sounds like it's straining; it just doesn't sound right.

You absolutely should be running a basic particulate filter, if only to protect the machine from debris, it doesn't matter if the water at your house is perfect, should still be installed. A generic 10" filter and housing from Chris Coffee is sufficient, with miniscule yearly cost.

I agree the blockage would not be in your supply line, if there is one, it will be somewhere in the machine, possibly at the flow restrictor.

Reporting back:

The water supply line, where it plugged into the boiler, was at too sharp an angle, causing a kink and preventing water flow. I feel like an idiot, but the tech said it happnens more than you'd believe. I installed a particulate filter, which extended the supply line another few inches, so the problem is resolved.

Dumb error on my part aside, it was good timing. I was grinding a shot for the tech when my grinder stopped working, and he happened to have a spare Mazzer in the van for me to borrow until my grinder is repaired. What luck(?)!

Thanks again to everyone for the help and advice!