Choosing the right grinder for your coffee business is an important decision.  If you are looking for the best coffee grinder for espresso and you find this blog useful, you may benefit from reading all of the articles in the series, click here to start at part 1.

Function – Temperature Stability.  Fan Vs Thermal Block Vs No Temperature Stability Device

Every time an espresso grinder is used, the motor and burrs create friction and generate heat.  One coffee at a time, the temperature of the grinder and burr chamber increases, most dramatically when the grinder is used continuously.  If the grinder is pushed further and further, it will eventually overheat.  If this happens the grinder will stop working and the barista will have to wait for up to an hour for it to cool down, before it can be used again.

As well as this, the colder a coffee bean is, the more brittle it is.  Brittle beans break into smaller pieces when they fall into the grind chamber even if the grind setting has not been adjusted.  Remember, the smaller the grind particles are, the more compact they will be after tamping and the slower the extraction will be.  The right extraction time is fundamental to a well-balanced espresso – If you would like to swat up on this, it’s a good idea to visit the opening paragraph of Part 3 of this blog – Adjusting the grind size.

For these reasons, grinders with fans and thermal blocks are more reliable at higher volumes, and they make it easier for the barista to consistently serve well balanced, sweet espresso.

Grinders Available with our Full Care Rental Service


Burr Diameter/Type



Thermal Block

Mazzer Mini





Mazzer Super Jolly





Mazzer Major





Mazzer Robur





VA Mythos 1 





Grinders with no Temperature Stability Device

By this I mean the coffee grinder has no fan or thermal block.  Our Mazzer Mini and Super Jolly on-demand and manual grinders fall into this category because they are the smallest two grinders in our range. They are designed for low to medium volumes, so do not need temperature stability features as much as the larger grinders in our range.

Positives of no Temperature Stability Device

Price – If you are opening a small coffee business then there is not much to be gained spending extra money on the fans you find in the larger Mazzer Grinders.  The infrequency of use will keep the grinder cooler so it will not overheat, and the grind size will be less effected by temperature fluctuations.

Negatives of no Temperature Stability Device

Overheating – The Mazzer Mini and Super Jolly espresso grinders cannot be used to continuously.  As discussed, the grinder will overheat and simply stop working.  Quite possibly when you need it the most.  If you serve medium to high volumes for any part of the day, it is worth considering a grinder with temperature stability devices.  Turning away customers is much more expensive than spending an extra few pounds each week on better grinder.

Extraction Time Consistency – When you grind the first dose of the day the grinder will be cold, as will the beans that fall into the grind chamber.  This will mean a slower extraction because the beans will be more brittle and therefore break into smaller pieces.  Effectively giving you a smaller grind size, even though you haven’t adjusted the grind ring.  In-experienced baristas will not understand this and may blame the cleaner or the grinder fairy for sabotaging their equipment overnight, (unlikely if you think about it) causing friction between employees and un-necessary stress.

Then, if the grinder is frequently used to serve your customers it will gradually heat up.  The heat from the grinder will slowly heat up the beans in the hopper and they will gradually start to break into larger and larger pieces, as they become less brittle.  This will result in your extraction time gradually reducing, and your coffee potentially being under extracted, until a grind size adjustment is made.

Throughout the rest of the day the grinder will heat up and cool down depending on how busy you are, meaning more grind size adjustments are needed to stick to the target extraction time recommended by your coffee roaster.

Temperature Range of Grinders with No Temperature Stability Devices

Temperature Range of Grinders with No Temperature Stability Devices

Grinders with a built in Fan for Cooling

The espresso grinders in our range that have a fan but no thermal block are the Mazzer Major and the Mazzer Robur.

Positives of a Grinder with a Fan

The grind size is less affected by the grinder heating up – When the motor and burrs create heat because they are working hard the fan is ready to help.  The fan increases airflow in the grind chamber to help keep it cool.  This saves the barista the trouble of having to move to grind size finer and finer as the coffee and the grinder continue to heat up.  As discussed, the more consistent the grind size is, the more consistent the espresso will be.

The grinder is less likely to overheat – Another benefit of keeping your grinder cool is it is less likely to stop working altogether.  This inevitably happens when you are busy, and the half hour or so you will need to wait for it to cool down before it starts working again can go very slowly.  Especially if you are having to turn customers away.

Negatives of a Grinder with a Fan

Price – The cost of renting a Mazzer Major or Mazzer Robur is more expensive than the Mazzer Super Jolly grinder that does not have a fan.  But for many of our customers it is a price worth paying to make sure their grinder is up to the task.

Suitability – The Mazzer Robur is not suitable for small coffee volumes.  With 71mm conical burrs, the Robur is the most high-volume coffee grinder in our range.  As the Mazzer grinders do not have a thermal block, all of the extra metal used to build the grinder, needs to be heated up.  This lengthens the process of heating the grinder up in the morning (or after any period of light use) and making the necessary adjustments.

Temperature Range of Grinders with a Fan


Grinders with a built in Fan & Thermal Block

For those who want the best protection possible against temperature instability, the Victoria Arduino Mythos 1 espresso grinder is a great option.  Firstly the Mythos 1 has 2 fans, which are strategically positioned to maximise airflow through the grinder.  Obviously, more effective than using just one fan.  The grinder also has a thermal block which connects the bottom of the hopper with the entrance to the grind chamber.  As the beans slowly pass through the block, they are gently heated to minimise the effect of the grinder cooling down when not in use.  The thermal block and fans work together to minimise temperature fluctuations, making the life of the barista easier and the coffee you serve better.

Positives of a Grinder with a built in Fan & Thermal Block

The grind size is not affected by the grinder being cold – When your barista arrives for his/her shift in the morning they are less likely to find that the first coffee they make is over extracted.  This is because the beans and grinder are already heated and therefore significantly less brittle than if the grinder and beans are cold.  But the thermal block is not only useful for the first few coffees, it continues to work with the fans throughout the day for a much more stable grind temperature.  Your baristas will not need to make as many grind adjustments, which means less interruptions to service and a more consistent espresso for your customers.  

The grind size is less affected by the grinder heating up – The Mythos 1 has 2 powerful fans to cope with the busiest of baristas.  The Mythos one can grind approximately 7-8 kilos per day without overheating.  That’s at least 350 double espressos per day.  For businesses who need to grind more coffee than this a popular choice is to have two Mythos 1 grinders to spread the workload.  Another reason for this, is there is a spare grinder should one stop working.

Less coffee and time is wasted making adjustments – Because the temperature of the Mythos 1 grinder is more stable, the barista does not need to make as many adjustments to serve consistently well-balanced espresso.  This means less coffee is wasted purging the grinder and more time can be spent making coffee and interacting with your customers.

Negatives of a Grinder with a built in Fan & Thermal Block

The thermal block needs time to heat up the grinder and coffee beans – It will take at approximately 20 minutes for the thermal block to heat up and transfer that heat to the beans and grind chamber.  Therefore, to benefit from the thermal block the grinder needs to be turned on and left to heat up before use.  Leaving the grinder on overnight is expensive and a waste of energy, so most baristas will arrive in good time to heat the grinder up before serving.

Price – If your coffee business is serving medium to high volume espresso the upgrade price for a Mythos 1 is insignificant when compared to the benefits it provides.  However many new coffee businesses overestimate coffee sales and end up with a grinder that is a little too pricey for their requirements.  With our Full Care Service, we include free grinder changes as and when required, so there is little risk in starting with any grinder in our range.

All grinders can overheat – Like with all other coffee grinders, if pushed beyond approximately 8 kilos per day, it is possible that the grinder will overheat.  As discussed, it is generally favoured to have a second grinder rather than another upgrade at this stage.

Temperature Range of Grinders with a Fan and Thermal Block

Fan Vs Thermal Block Vs No Temperature Stability Device Summary

Due to their output requirements, larger coffee grinders are generally equipped with more temperature stability devices.  So simply choosing a larger grinder will protect the grinder from overheating and the time wasted making un-necessary adjustments.  This is what the Mazzer Major and Robur do with the fan they use to cool the motor and grind chamber.  As well as this, larger grinders have a more powerful motor and bigger burrs, so even without the additional cooling power of a fan they are capable of grinding more coffee before overheating.

It is the Victoria Arduino Mythos 1 grinder, with it’s two fans and thermal block that raises the bar in grinder temperature stability.  But this does not mean that if you are using a Mazzer Super Jolly Grinder and the grinder overheats sometimes you need a mythos 1 grinder.  The Mazzer Major has a bigger motor, larger 75mm burrs and a built-in fan to keep it cool.  This is significantly cheaper than upgrading to the Mythos 1 and will probably solve the problem.

The Mythos 1 is popular in coffee shops that serve high volume, and/or want to serve their speciality coffee to its full potential, so it is often favoured by baristas because of their personal aspirations to serve great coffee. To use the Mythos 1 effectively, the same fundamental knowledge of brewing espresso is required. The advanced temperature stability simply reduces the adjustments needed to keep the recipe on track throughout the day.  So if you have a knowledgeable, and interested barista they are sure to manage, and serve great coffee with a simpler, more affordable grinder.

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