I recently acquired a pre owned, and very well maintained Livia 90. It's fully functional and will pull a shot reasonably well.

That said, when I turn it on, it will get to pressure at about 1.2 bars (1/4 of the way into the "green zone"). However, after this, it will slowly bleed pressure back down into the "blue zone" at which point the light turns back on and it builds pressure again.

I'm new to espresso home brewing, but this seems like it's likely a malfunction. Shouldn't it maintain pressure the entire time?

This process happens whether I am leaving it idle, pulling a shot, or back flushing.

If this is a malfunction, and guidance on what might be causing it?

Many thanks!

I don't think you have a problem, it is normal for the pressurestat to control within the range you describe.
The actual values are ~0.9 on, and ~1.3 bar off.
A Livia 90 heater has on-off control, not PID.

Thanks for the reply.

I'm about to replace the group gasket, as it likely needs it. One other question, though. When I brew espresso, or even when the machine is just holding pressure between brews, the "blow off valve" (I don't know what else to call it - it's the spout in the lower left that emits water when you back flush) slowly drips water. Maybe 1 drop every 5 seconds or so. Is this normal?

I continue to feel like something is wrong with my machine. As I watch this video, I notice that the pressure valve actually stays within the green area, and maybe even builds a little. Again, note that mine dips down into the blue as I pull shots (or don't do anything...it just bleeds pressure, and then turns back on every ~30 seconds or so). Also, after I pull the shot, I don't get the pressure release like in the video. When I put the cleaning disc in the basket, I can get the pressure valve to release, FWIW.

Any ideas?

Sounds like it is working but not up to par.
Do you hear any steam leakage when up to pressure?
If so, you might want to pull off the top cover and sides, then replace the water tank, and run it so you can track this down.
Possible future (or, present) exercises could be cleaning the 3way valve, fixing or replacing the vacuum breaker valve, or considering the pstat and the piping leading to it.

I have had a Livia 90 for 20 years. It sounds to me like you need to adjust the pressure stat. Take the cover off. The pressure stat is on the right-side. It has a slot on top for a screwdriver. If I remember correctly turning the screw counter clockwise will increase the pressure. You can quickly see which way works as the light will come on when it's heating. It only takes a small movement of the screw to make a rather big change. Mine stays in the green when I am pulling a shot or steaming milk.

I've got a Livia 90 and agree with the suggestion about adjusting the pressure stat. On my machine, it will pressurize up to the top end of the green zone. Before pulling a shot, I always bleed off enough hot water to have the machine cycle on and make sure that's it's got enough pressure margin to not drop out of the green zone while pulling a shot.
Regarding the pressure relief valve leaking water, I had something like this happen to me about a year ago. I heard an intermittent hissing, which turned out to a slow leak from the pressure relief valve. A drop of water would leak out from the pressure relief valve and vaporize when it heat the hot boiler, which led to the hissing sound. Taking off the top and sides of the machine and then running it made this obvious. I removed the pressure valve and then used some teflon tape on the thread and reinstalled it and that fixed the problem.

@Flahertb and @garyb

Thank y'all so much! I turned that screw and it made all the difference.

Still struggling to get a good whirlpool in a way that creates the "latex paint" texture, but I suspect that's user error. Out of curiosity, do y'all use the "turbo tip", or the standard steam tip with 4 holes?

It is normal to see the pressure slowly rise when the heating element is "on" and slowly fall when "off"-red lamp not lit.
When brewing, the cooler water running through the heat exchanger tube will cause the boiler water to cool and lose pressure, and will increase the pressure fall or slow or even stop it as appropriate.
However, if the water in the boiler has been replaced by scale, there will be a greater cooling effect from brewing, as scale has less heat capacity than does water.
My Livia typically stops, but does not reverse, pressure rise when brewing.
Significant fall when brewing even with the heating lamp lit would indicate a need to descale.

Hi Texas Bill: I got a 4 hole steam tip from espresso parts.com, for $19.80(pricey yes?), the holes are extra micro small or something. All I know is it makes the silkiest micro foam with ease, definitely the best, other than my Cremina. I have my Livia 90 machine from 1996 that has no pressure gauge, set to turn the element on at about 0.9 bar, and then it goes up to about 1.1 bar, maybe a bit more as it rides the heat wave.

With no pressure gauge on my machine to see what is going on, I hose clamp a pressure gauge onto my steam tip (brake hose between the pressure gauge and the steam tip. I also use this to check to see if machine gauges are accurate. Anyway, once I adjust my P-stat (a little goes a long way in adjusting), I let the machine cycle a few times and then remove the brake hose and put my steam tip back on.

So when my machine cycles without a pressure gauge to look at, I just know that when my element light turns on, my boiler has cooled off to about 0.9 bar, and when my element light turns off, my boiler is at about 1.1 and slightly rising over that with momentum, to maybe 1.15....

These two measurements are just what the boiler temperature is doing, so, how hot and dry your steam will be, and how "super charged" hot water will come out of the water tap(notice how it spits and makes a lot of noise). 0.9bar=245.84F. 1bar=248.76F. 1.1bar=251.53F

That's a lot of heat, heating up the heat exchanger tube in the middle of the boiler! That little HX tube only holds about 5 ounces of water, just shy of it, because that is how much citric acid solution I can fit in the tube to soak the scale out.

Scale build up just impedes everything(think of it like LDL cholesterol, yeah, I just had my blood work done.)......, from the pressure relief valve on top of the boiler, which was being held in the open position on my machine, because of scale, to the water level probes. Once the water level probes are coated with scale they have a hard time sending signals(calling for water, or telling it to stop). Also, scale build up on the element makes it work harder, spending more energy(i.e. Money$$), time, and making things work overtime.

The worst part about scale building up, is that little flakes can come off and float around and partially block your pressure gauge and could give it a false reading, or a flake can give your p-stat false measurements, making them act wonky, or it can inhibit the 3-way valve.... Lastly the scale build up on the HX tube just delays recovery time of heating the water that is actually going to get to your ground coffee in the portafilter.

With my machine all clean, and freshly descaled, I watched and timed the heating cycle of my boiler element. With the cover off, and no insulation around my boiler, my Livia cycles every 34-36 seconds..... meaning it takes that long to loose heat, from the top of my temperature cycle 251.5F to the bottom of it at 245.8F.

During the rise or fall of the temperature in the boiler, my cooling flush only depends on how long the water in my 4.95 oz HX tube has been sitting there idle. Normally for my routine in the morning, it takes about a 3-4 second cooling flush until the water stops spitting and becomes a nice stream. If your P-stat is set higher, then your cooling flush times will be different. Now on an old Livietta HX machine I have from 1985(aka Fire Breathing Dragon, it takes a cooling flush of about 8-12 seconds depending on how long the water is sitting idle.