Why does the Livia GP's temperature reading drop when I pull a shot?
Thank you for the interest and support since we launched the Livia GP. In this series we are taking a closer look at the design choices behind the machine, based on the questions you have been sending us.
One of the most common: "Why does the PID temperature drop once I start making an espresso? Shouldn't it be stable like other machines?"
The answer has to do with how the Livia GP heats water and where the sensor sits.
1. What a PID does
PID stands for Proportional Integral Derivative. In practical terms, think of it as a smart thermostat. It reads the temperature at one point in the machine and adjusts the heating element to hold a target.
On a conventional dual-boiler machine, the PID sensor sits in the coffee boiler. Water cools a little as it travels from the boiler to your coffee, so the PID is set up to predict what the boiler needs to be for the water to arrive at the temperature you chose. The number on the display is that boiler reading. It stays steady during a shot because the boiler holds a large volume of water, and the sensor never sees the fresh water coming in to replace what left.
It works like the thermostat in your hallway. It reports the temperature where it lives and estimates the rest of the house.
2. The Livia GP shows real temperature
The Livia GP has no traditional coffee boiler. It uses a heating block with a spiral channel cut through it, which we call SpiraFlow. Water enters one end of the spiral, passes the heating elements, and leaves the other end at your set temperature on its way to the group head.
This is why the Livia GP heats up from cold in about three minutes. There is no tank of water to bring up to temperature, only the block and the water moving through it.
It also changes what the display means. We placed the PID sensor at the entrance to the spiral, where water first meets the block. That lets the heaters react as quickly as possible to whatever is coming in. The number you see is the actual temperature of the water at that point, measured in real time.
3. The dip is SpiraFlow working
When you start a shot, fresh water begins flowing into the spiral. The sensor at the entrance sees that water arrive and reports it. That is the dip on the display. At the same time, the heaters are bringing that water to your target temperature by the time it reaches the end of the spiral and hits the coffee.
Because the block heats water as it passes through rather than storing it, there is nothing to run low and nothing to recover. Whether you pull one shot or ten in a row, the water reaching your coffee is at the temperature you set.
The moving number is the machine telling you what the water is doing.
Like the dual vibration pumps, this was a deliberate choice. Fewer parts and a faster heat-up, with a display that tells you what the water is actually doing. It is the same approach we have taken since the Livia 90: simple to service and built to last.