My coffee maker doesn’t heat

The lack of water (or milk) heating in electric coffee makers is a common issue that users face. Several factors can be responsible for this inconvenience.

The origin of the problem can vary depending on the type of coffee maker and the technology used. For example, espresso machines typically use one or two boilers, with one dedicated to the steam wand if there are two. On the other hand, coffee pod machines employ the Thermoblock system.

Conducting a detailed analysis to identify and effectively resolve the issues is important. In this article, we will focus on the most important aspects so you can enjoy a hot cup of coffee again.

How does a coffee maker heat the water?

Let’s review the two main methods that coffee makers use to heat the water and gain a better understanding of how the machine operates:

Thermoblock system: This is the most common method in modern household coffee makers. Instead of storing water, the Thermoblock system heats it as it passes through the device. It is an efficient and cost-effective system.

Water boiler: This is the traditional method. In this case, water is stored in a boiler and heated using an internal heating element until it reaches the ideal temperature for coffee extraction. Temperature precision is crucial, as all the water in the boiler is maintained at the same temperature.

The main difference between the two systems lies in the boiler being a component that can be disassembled from the coffee maker for repair or replacement. In contrast, in the case of the Thermoblock system, when it malfunctions, it is usually replaced with a new one that includes the built-in thermostat.

Now that we know how coffee makers heat the water let’s analyze the problem and its possible causes.

Why doesn’t my coffee machine heat up?

Many of the problems related to water temperature involve several elements. For example, a faulty thermostat can cause a hot melt to melt; even if you replace it, it may melt again because of the faulty thermostat.

  1. If your coffee maker no longer heats, it is obvious that something is wrong with the Thermoblock or the boiler. In the case of the Thermoblock, there may be a blockage or a defect in its thin internal circuit, while in the boiler case, the internal resistance may be broken.
  2. Another possibility is that the hot fuses protecting the boiler and the Thermoblock have melted. However, the machine will likely not work in modern coffee machines for safety reasons.
  3. The thermostat could also have a fault (which controls the temperature). It is possible that the thermostat switches off the boiler heater or Thermoblock at a lower temperature than appropriate or does not activate these heating elements at all.
  4. The most common cause is limescale build-up in the internal circuits. When scale builds up, it creates an insulating layer that prevents the water from getting hot enough.
  5. In some cases, in newer brewers, I have observed that faults in the control board can cause the heating element to malfunction. However, diagnosing this is often quite difficult and is usually done by eliminating other possibilities.

What happens when a coffee maker doesn’t heat up?

The situation varies depending on the type of coffee maker. In the case of an espresso machine, the operation is usually normal, meaning that water continues to flow through the circuits, and the pressure pump keeps working. However, the resulting coffee comes out cold, as the water used for extraction is at room temperature.

On the other hand, if it’s an electric drip coffee maker or a coffee pod machine that doesn’t heat up the water, it generally won’t function properly. However, the responses to this issue can vary widely depending on the specific brand and model of the machine.

A similar issue: the coffee maker is not hot enough.

It is more likely for a coffee maker that uses the Thermoblock system instead of a boiler not to heat up properly. This refers to point 4 we mentioned earlier.

In these cases, the heating element generally functions correctly, but the circuits are obstructed by sediment and limescale. As a result, the water does not flow with the necessary fluidity, and the heating process does not occur properly as the water passes through the Thermoblock.

Therefore, if you notice that your coffee maker is not reaching an adequate temperature, you should first initiate a descaling process.

What to do when a drip coffee maker does not heat

Drip or filter electric coffee makers are very popular in countries like the United States. These machines typically operate with a heating element that generates heat in the water that will be filtered through the ground coffee in the cone.

In more severe cases, the heating element itself may become damaged, although this is uncommon. The electric voltage reaches the heating element through one or two thermal fuses. These thermal fuses operate based on temperature (not voltage, like regular fuses), and one of them often breaks.

Thermal fuses tend to be damaged due to excessive temperature, for example, when the coffee maker is left on for a long time or several years. As a result, the electric voltage does not pass through the fuse or reach the heating element, causing the coffee maker not to transmit heat to the water. Replacing the thermal fuse with a new one is sufficient in these cases.

As you can see, the process is not complicated, but it requires specific knowledge and knowing how to open and reassemble your coffee maker. Another option is to take it to a service technician, of course.

If you do it independently and at risk, you can purchase thermal fuses on Amazon. They are very affordable, but ensure they have the same capacity as the one you are replacing. The thermal fuses used in coffee makers are usually rated at 240°C.

How to repair a coffee maker that doesn’t heat up?

The most common way to repair an electric coffee maker that doesn’t heat up is by replacing the Thermoblock or boiler entirely, including the thermostat.

However, this should only be done after verifying that the thermal fuses and control board are in good condition. Thermoblocks and boilers can be purchased on Amazon, but installing and connecting them correctly inside the coffee maker can be complicated, especially depending on the brand and model of the coffee maker.

As I mentioned before, it’s important to perform one or multiple descaling processes before replacing any physical component of the coffee maker.

My coffee maker heats up, but the water doesn’t rise

This is a different situation that occurs in electric drip coffee makers.

In these coffee makers, cold water descends from the reservoir to the heating element to be heated, and once hot, it rises to mix with the coffee in the cone where the filter is located.

These are two independent paths, but these machines have a check valve at the bottom of the reservoir that prevents hot water from returning to the reservoir. In other words, it forces it to follow the correct path.

If this check valve (usually a ball) doesn’t function properly, the water will heat up, but it won’t reach the filter, and therefore, you won’t get any coffee.