Possible over heating of Linea PB

I’ve been running my take away only coffee hut for three months now and all was well up until two days ago. While I was making drinks order I noticed the red ring lights on both groups had turned off and that the boiler temperature has risen to 96 degrees. When I stopped using the machine the temperature dropped back to the preset of 94. It has been rather humid for the past couple of days. Was wondering if that could be a factor or if this is a sign of something more serious?

I’m usin a bottled water pump system with a bestmax XL filter.

Any ideas or help would be very much appreciated



Assuming you always leave your machine on, have proper water (130-160TDS) and electrical (proper ground and amperage) feeding the machine, It could be a handful of things but a few things I would check first is:

A - The great thing about the PB is that you can get into the programming and adjust/check the coffee boiler and steam boiler temps settings. If the temps are set properly (usually around 205F for coffee boiler and 255F for the steamboiler) it could very well be the temp probe isn’t functioning property.

B - Double check that the wire collar on the temp probes are snug. IF they were loosened it could send a false signal to the board.

C - Could be that the pump system your using isn’t supplying enough pressure. Meaning if you were busy the boilers wouldn’t stay full/fill quick enough and therefore could trigger the high limits which disable the buttons. Whats the water pressure on the gauge when not pulling shots? should be over 4bars.

D - If the temps and probes are good, you may want to unplug the machine and slide out the control board to inspect for water. If water hit the control board it can totally short circuit some things. This is very unlikely but I have seen it before.

*note. Try to minimize the use of the hot water spigots, especially without a plumbed machine.
You gotta good machine, if it was installed correctly and is maintained it should last a lifetime.

1 Like

Hi Spencer thanks for the reply.

When not in use the boiler temp is moving from 93.3 up to 93.9 and back.

Are the probes easily accessible to check the wiring as I’ve no experience with this?

I’m using a singflo pump and the pressure when not in use varies from 6-12 bar.

I work in a rather confined space so I’ve been using the hot water spigot for drinks as I’ve no space for a boiler

Also I have been switching the machine off on an evening as I was worried about leaving it unattended over night.

What are the issues with my last two points?

I know these might be a few noobish issues but any help would be appreciated.

This is a picture of the water that I am using.

Couple things:

The temp ranges you have said are actually right on. The temp will always fluctuate a bit as there are heating elements in each boiler that kick on based on your set points (in the programming).

water pressure seems very high (and can damage the coffee boiler). Did you have a certified La Marzocco tech install it for you? There are several steps that need to be done to get it set up properly the first time. Two boiler machines have some quarks to them. You are looking for a static pressure of 4-6bars.

Technically speaking, the TDS of mineral water is way too high for espresso (this will effect coffee flavor as well as equipment performance/longevity). Also will void warranty on day one.

As long as you have plenty of water, you should always leave the machine on 24/7. By shutting it off every day you may come into issues. Think about the seals and fittings expanding and contracting with temp fluctuations that occur when powering it down. You’ll also have a lower electric bill if you leave it on 24/7. I know it sounds crazy but I compare it to turning off your AC at home when its 100 degrees F out and then turning it on when you get home from work. It takes considerably more energy to bring the room down rather than kicking on occasionally throughout the day.

You should really have a tech come check it out. Give La Marzocco a call to find a certified tech to come check it out.

Hello, good morning!

We have the same problem in Hungary with the Linea PB 2AV.
The red ring lights on both groups had turned off and that the boiler temperature has risen to 97 degrees. The normal temperature is 92,5 degrees. We changed everything, wire, solid state relay, probe everything and nothings happened. And then we look inside and we saw there is a hole on the heater. And now is working. :slight_smile: Your machine is working now?
Have a great day :slight_smile:


Yeah everything is working great now. Needed to bleed the group heads and that seems to have worked.

Many thanks,