At the time of preparing a perfect espresso coffee, although there is no exact formula defined, there are some generalized parameters that should be followed to obtain an excellent espresso coffee with a classic espresso machine, such as the following:
- Use 7 grams of ground coffee.
- The coffee should have a relatively fine grind.
- The infusion should be made at 187 degrees Fahrenheit.
- The coffee in the cup should be at 160 degrees Fahrenheit.
- A ratio of coffee to water between 1:1.5 and 1:2.5
- The preparation should last 5 seconds of pre-infusion and 25 seconds of infusion.
- The final amount of coffee extracted should be 25 milliliters.
- The water pressure during brewing should be 9 bar.
Altering these reference values too much when preparing an espresso will take us far from obtaining the ideal espresso. Then, the temperature of our Nespresso coffee machine is essential for coffee preparations, so you should intervene if the temperature drops too low.
The thermostat or heating element of the Nespresso is failing
The Nespresso coffee machine stops heating water when there is a malfunction in the thermoblock or thermostat. Our coffee maker communicates this to us through the espresso and lungo button lights; these will start flashing with three flashes every 2 seconds.
In our article on the meaning of the lights in Nespresso coffee makers, we mentioned that in this case, the machine goes into failure mode and will block the preparation of any coffee. That said, if there is a malfunction in the thermoblock or thermostat, there will be no change in the temperature of the coffee simply because the coffee will not be able to be prepared.
However, when the temperature of the coffee begins to vary, either lower or sometimes higher, it will be a sign that something is wrong with the machine, and you can act immediately to avoid major problems that could lead to the definitive failure of the thermoblock or the thermostat.
Suppose, during the preparation of your coffee, the temperature drops below 181ºF. In that case, it could mean a build-up of lime inside the machine, for which we recommend one or more descaling operations to solve the problem.
How to diagnose a Nespresso thermoblock or thermostat failure
The maximum capacity to which a standard thermoblock of a Nespresso coffee machine can heat is up to 221ºF due to its design. But in normal conditions, it can heat to about 187ºC because the thermostat opens and closes the circuit at 181 and 192 degrees Celsius, connected in series.
With a continuity test, with the coffee maker turned off, you can check the correct operation of the thermostat. If there is such continuity, it can be assumed that everything is fine; however, on rare occasions, it may show continuity and operate in an inadequate temperature range.
- If there are faults in the thermoblock or the thermostat, the coffee maker will not only detect it but also prevent the preparation of coffee.
- In the majority of cases, the decrease in the coffee temperature will be a direct consequence of the accumulation of lime inside the machine on the internal walls of the thermoblock.
- If the problem persists after descaling several times, it is recommended to replace the thermoblock and thermostat, although this can be a bit costly. A new thermoblock can cost up to 90 dollars and is not easy to obtain, but you also have the alternative of getting a second-hand coffee maker with the thermoblock in good condition. On eBay, you can find them for about 20 dollars.
You may be interested in: Meaning of the lights on the Nespresso VertuoLine coffee machine.