One of the most common problems encountered by users of electric coffee machines is that the coffee maker does not heat the water (or milk), and this may be due to various factors, but we will analyse the most important ones.
First, we must specify that the reasons why a coffee maker does not heat water can vary depending on the type of machine. Those that make espresso work differently from filter machines.
What to do if your coffee machine does not heat the water (espresso)
Let’s review the two main methods that an espresso machine must heat the water (a little bit of coffee mechanics, to put us in the situation):
- The Thermoblock: is the most common system in any modern domestic coffee maker. It doesn’t store the water but takes it from the tank and heats only the water needed to make the coffee. It is a cheaper and more efficient system.
- The water boiler is the traditional method. The boiler stores the water and has a resistance inside that heats it. This precision is necessary: all the water in the boiler is always heated.
The same applies to automatic coffee machines and capsule coffee machines. They all mostly make espresso coffee.
One of the differences between the two systems is that the boiler is a separate part that can be removed from the coffee machine, repaired, replaced, etc. The Thermoblock, on the other hand, when it breaks down, is usually taken to the technical service and replaced by another one.
Once we know the two ways in which espresso machines heat water, let’s analyse the problem and its possible causes:
Why is my coffee maker not heating up?
If your coffee maker no longer heats, it could be because the Thermoblock has broken, or the resistance in the case of boilers, or more commonly, one of the thermal fuses.
Another possibility is that the fuses have been damaged by a malfunction of the thermostat (which does nothing but control the temperature). If this happens, it is most likely that even if you replace the damaged fuse soon after, the new one will blow again as well. You will need to replace the thermostat so that excess temperature is warned and managed correctly.
When replacing your thermostat, you should ensure that the voltage and operating temperature are the same as the one you are changing.
What happens when a coffee maker doesn’t heat? If it is an espresso machine, the operation is regular (i.e. the water continues to pass through the circuits, the pressure pump continues to work). Still, the coffee comes out cold at the end, as the water used in the filtering will be at room temperature.
If it’s a drip coffee machine that doesn’t heat the water, then it usually doesn’t work. But there are almost as many answers to this as different brands and models of machines.
A similar problem: the coffee machine is not very hot
The coffee maker not heating up well is more likely to occur in Thermoblock coffee makers than in those using a boiler.
The heating system is usually working correctly in these cases, but the circuits are blocked by sediment and lime. The water, therefore, does not circulate as smoothly as it should, and because the Thermoblock heats the water as it passes through it, the process is not carried out correctly.
Therefore, the first thing you should do if you notice that your coffee maker is not very hot is to start a decalcification process.
What to do when a drip coffee maker does not heat
Then there is the drip, or filter, coffee makers, which are very popular. These coffee machines usually work with a resistance that generates heat in the water that we will filter in the ground coffee cone.
In the most severe cases, the resistance itself is damaged, but this is not the norm. The voltage reaches the resistance through a thermal fuse (usually three). Thermal fuses work by temperature (not by voltage, like standard fuses), and many times it happens that one breaks.
Thermal fuses are often damaged by excessive temperature (for example, when the coffee machine is left on for a long time or several years).
Consequently, the voltage does not pass through the fuse and does not reach the resistance, so in the end, the coffee machine does not transmit heat to the water. It is sufficient to replace this thermal fuse with a new one in these cases.
As you can see, the process is not complicated, but you must have specific skills and also know how to open and reassemble your coffee maker. Another option is to take it to technical service, of course.
If you decide to do it at your own risk, you can buy your thermal fuses at Amazon. They are very cheap, although you should ensure they have the same capacity as the one you are replacing. The ones that are used in coffee machines are usually 240 ºC.
How do you repair a coffee machine that doesn’t heat?
To repair an electric coffee machine that does not heat is most common to replace the Thermoblock (complete), a hot plate or the thermostat.
It makes sense to take it to a service centre and have it fixed there in the first case. The entire part must be dismantled and replaced with a new Thermoblock. Thermoblocks can be bought from Amazon but mounting them and connecting them correctly inside the coffee machine is another matter.
Replacing a thermal fuse is easy, as you can see in the videos. What is more complicated is detecting which fuses are damaged or blown.
Here’s an example of a (Mr Coffee) coffee maker that doesn’t heat up. This is a filter coffee machine in this case.
My coffee maker heats but does not turn up the water
It is a different situation, and it happens in filter coffee machines.
In drip coffee machines, the cold water goes down from the tank to the heating element to get warm, and then when it is already hot, it goes up to mix with the coffee in the cone where the filter is. There are two independent paths, but these machines have a non-return valve at the bottom of the tank, preventing the already hot water from going back into the tank. That is, it forces it to follow the right path.
If this non-return valve (usually a ball) does not work correctly, the water will be heated but will not reach the filter, and therefore you will not have coffee.