Choose the right espresso machine

Differences between groupheads

BZ Thermal Efficient

Produces espressos with sharper clarity.
Less space for remnants to get retained, which can cause a “dirty” taste from stale and decaying coffee.
Faster startup and recovery time.
More reliable with a better engineering design.
Affordable long-term repair.

Classic E61

Slightly smoother extraction with a period of pre-infusion.
Components are easily available worldwide.

Spring Lever

Dynamic pressure profile that releases a wider spectrum of aromatic notes.
A larger amount of preinfusion for smoother extraction.
Highest durability
Affordable long-term repair.

Simplified E61

Has the pre-infusion found in E61.
Less wearable components.

 

 

Difference between E61 or BZ?

The BZ grouphead can be seen as a redesign of the E61 which was invented almost 60 years ago. The main idea is to create a machine that is smaller, more serviceable, safer and reliable. Particularly important when it comes to industrial usage. BZ is also a little less pricey as E61 utilizes a lot of metal used for its grouphead.

E61s are easy to use, easy to pull a nice looking shot mainly due to its inherent process of forming a pre-infusion. Pre-infusion is to allow water to spread evenly above the coffee powder before pressurization for extraction takes place. This can reduce channelling issues happening during extraction. However, it does come with some shortcomings. Remnants are often retained in the compartments where pre-infusion builds up. Such retention of remnants can gradually accumulate and what’s left there and ignored can eventually go rancid. These remnants of decaying and stale coffee, mixing with your freshly made espresso, can cause a “dirty” taste to your coffee. As such, it is more important that grouphead flushing is regularly done.

N.B: Spring lever machines won’t have the same issue despite the huge amount of pre-infusion that it has, as it forces out most water and remnants during extraction.

The E61 grouphead circulates hot water from the boiler to stabilize its grouphead, this is called a thermo-siphon system. It can stabilize the temperature to match closer to the temperature of the water in the boiler, especially for single boilers or double boilers, not much help for heat exchangers. This feature does come with some disadvantages. The flip side is there’s a much higher chance of metal leaching into the water from the large amount of metal used in the E61 grouphead, especially with the continuous circulation of water around it.

N.B: Bezzera is a century old brand that is probably the most forward in the espresso machine industry for material engineering. One thing that consumers can’t observe just from looking at the specifications is they are using the most advance “no-lead” or extremely “low-lead” brass. Which are also additionally plated with a coating for extra protection. They are currently the best in this aspect among similar tier of espresso machines, weighing huge emphasis on product safety as well as on good engineering design. The reason why brass has remain to be the choice of metal is because of its inherent strength, durability and thermal conductivity.

Despite the reputation of the E61’s thermal stability, this stable condition will only be true if the machine idles for a long time. Else the displacement of water in the boiler, or using the steam wand can lead to a drop of temperature in the boiler followed by the grouphead. This explains why some E61 users felt frustrated with its temperamental stability. As such, E61s with heat exchanger boilers should use a much bigger boiler of at least 2 litres to reduce such displacement effects. Since it alway requires a larger boiler, and it requires the water to heat up, circulate around to warm up the huge chunk of metal in the grouphead. The start up time required is almost 70 percent longer compare to the BZ.

Both E61 and BZ are overall both considered reliable.
This is the exploded view of the E61 grouphead, which was invented in 1961, that is almost 60 years ago.

One thing to note about the E61 is despite the grouphead is solid with its huge mass of metal. There’s actually a lot of wear and tear happening in it, as the gears rub against each other during usage. As well as a lot of gaskets and lubrication applied in it that can go wrong over time. There are in total about 25 of such loose parts inside that can be worn. Normally a few worn parts might not cause any alarming issues, but they will have to be replaced sooner or later.

Now look at the BZ grouphead below which was invented only in the past few decades.

As you can see, the BZ is a much simplier design using two electrical components to replace dozens of loose parts to control the flow of water and heating of the grouphead. The amount of parts that can be worn, is now reduced to about 5 pieces, that’s almost an 80% reduction. Although it sounds like there are more electronics, but from our records, these two electronic components are pretty reliable and rarely fail. Also note that almost the entire grouphead(Part 38 to 43) can be removed for thorough cleaning. There is also very little space space for remnants to possibly retain. That is how it gets its “clean” taste with good clarity from all the coffee notes.

From our service records, the cost to service the E61 should be higher as it requires much more time and there’s also a higher chance of the components needing replacment.

E61s do have its advantages. As mentioned, the pre-infusion reduces the likelihood of channelling issue in the extraction, they are a little less picky on the grind setting. These two issues can be mitigrated by the user, by calibrating the grinder. In term of user-friendliness, we still think that the E61 might have a slight win over the other two systems. For users who love to fix their machines, the E61 has a lot of technical material found online for reference. It is also easier to find a technician to fix an E61, although it is actually easier to fix a BZ grouphead.

Are the material used in the machine safe??

Bezzera has their own factory to fabricate most parts of the machines, they craft their own boilers. As such, they have full control over the type of material used.

They are known to be the most forward in term of food material safety and had been using eco brass which has no lead or low lead. Brass has to be the preferred material for many parts of the machine due to its excellent heat conductivity, strength, corrosion resistance and natural anti-microbial properties. However brass is normally added with lead, else the material is very brittle making them hard to fabricate. Bezzera only use the highest quality brass that has insigificant amount of lead, almost considered no lead in the fittings and groupheads. All groupheads and most fittings are plated for extra protection, this means contact with lead is kept to the minimum. The newer models even have their solenoid switches, valves and pumps all made with the new material .

Most importantly, the boiler which has constant contact with hot pressurised water, is made of copper. Copper is an essential nutrient for the human body and the material has excellent anti microbial properties as well as one of the best thermal conductivity. Welding of parts are done with silver, which has no toxicity.

There are no toxic material, example aluminium, used in the machine.

Difference between boiler systems

Single Boiler

Smaller boiler for low usage.
Unable to froth milk and brew at the same time.
They are not recommended for drinkers who prefer to do mostly milk recipes like lattes or cappuccinos.
More affordable for repairs.

Heat Exchanger 

A boiler in a boiler system.
Able to froth milk and brew at the same time
Strong steam power due to the single larger boiler.
Water used for espresso is always fresh.
Better clarity in espresso.
Good for making any recipes.
More affordable for repairs.

Double Boiler

Two boilers, one for brewing and one for frothing milk.
Able to froth milk and brew at the same time.
More consistent temperature profile.
Good for any recipes.
More costly long-term repairs.

Summary

Heat exchanger should be the ideal choice for most users.  Heat exchanger can froth milk and extract coffee at the same time and is a lot more reliable than double boiler. Double Boilers have a longer water network, and requires a lot more electronic and mechanical components to handle the two boilers. Heat exchangers only has one boiler and it has an inner compartment to form another “boiler” in it. Cost to service the machine for an heat exchanger should cost closer to a single boiler, with even better reliability.

Technically, the more complicated the machine, the more parts it has, the less reliable or durable it becomes.

The way the temperature descends as heat exchanger extracts, can be a positive thing, especially for dark roasts. It can reduce the astringents pulled at the end of the extraction. In any case, there’s no clear evidence of which boiler system can produce a better espresso but reliability and serviceability is something that everyone has to deal with.

Where to learn how to use the machine?

To know how to use the machines, please refer to the Newbie Starter Guide or make an appointment to visit the Experimental room.

There’s no particular training required, but do note that spring piston espresso machines like the Bezzera Strega, will require some strength, height and physical capability to pull the lever down. It has to be handled with prudence to avoid injury and they are not suitable for petite users. Please follow the video guides closely on the Bezzera Strega product page before usage, particularly paying attention to how the handle can spring back without a loaded portafilter filled with sufficient coffee at the correct grind size to retain water in the chamber.

If you are going for a commercial or high traffic environment, you will require machines with rotary pumps which are rated for heavy duty usage, one exception is the Bezzera Strega TOP that doesn’t depend on the pump for extraction. For a huge traffic and think that one group is not sufficient, you can adopt having a couple of units and add-on modularly.

 

What’s a PID?

PID stands for Proportional, Integral, Derivative. For the espresso machine, it’s a digital component to control heat.

Imagine your boiler heats up, how can the machine detects that the machine is too hot and stop heating or heats up further if it’s getting cold?

In most cases, a pressurestat controls the temperature of the boiler by detecting the amount of pressure it has. When it’s too high or too low, it will send a signal to the heating element to react accordingly.

A PID is a digital temperature controller that replaces the pressurestat. It measures the temperature of the water in the boiler directly and switches on and off as needed.

A PID has two additional features over the pressurestat.

1. Full control of the temperature
2. Narrows the deadband of temperature fluctuation

The user can have more accurate control over the temperature and tune to his preference. This might be useful for exploring different flavours coming from the same coffee at different temperature, as well as controlling the intensity of its bitterness and sourness. It might be more noticeable if the user tunes by at least 2°C.

The pressurestat will create a fluctuation of temperature in the boiler, as it switches on and off according to the measured pressure. The PID is more reactive and will keep the deadband smaller, so the temperature is more stable.

Here is an example of PID versus Pressurestat.

If 90°C is the set temperature, a PID may sway around 0.2°C up and down, a pressurestat may sway approximately 2°C or more.

Which is more durable?

Pressurestats by itself should last for many years depending on the water condition, power stability and the ambient temperature. In some models, they come with a version with a heavy duty pressurestats with higher resistance, with longer expected longevity. We normally see pressurestats failing from limescale blockage than the component malfunction by itself. As such, it’s important to have the water properly softened to last it longer.

Pressurestat does not work alone, it works with a power relay which cycles power to the heating element. The relay also has a lifespan as it switches on and off all the time to regulate the temperature of the machine. Over time, the relay’s contact points can be corroded which makes them no longer effective. The lifespan of the relay largely depends on the ambient temperature, the duration of usage and stability of power. It is good to replace it regularly if you want to be more assured. They are not that expensive. It is also not a good idea to have them switched on all the time.

PID, like the pressurestat, does not work alone. It usually works with a solid static relay, a display, a water probe and a regulator.

Some may deem that having more electronics increases the risk of failure. The big advantage it has is the solid state relay can last much longer. The regulator and display may be more susceptible to damages from moisture or power surge, and the water probe can malfunction from limescale buildup. Overall, we still think that PID is a safer choice which should last longer especially if the user intend to switch the machine on for a prolonged period.

For PID espresso machines, you must not set the temperature above the boiling point of 100-degree celsius. As it may trigger the safety control to trip and shut off the power completely, and you will have a problem. As you will need to remove the hood to rest the safety or send it back to the service centres.

What’s the difference between Rotary and Vibration pump?

Vibration pumps are used in places where consumption level isn’t heavy.  They are about the size of your palm. They push water by having a piston that moves very quickly using electromagnetism. Vibration pumps can’t tune the flowing water pressure by itself, they always work at maximum efficiency, normally producing 15-19 bars of pressure, which is too high for decent espresso extraction.

For prosumer machines like the Bezzeara, vibration pumps work with an over-pressure valve aka OPV. The valve can be tuned to limit the pressure to flow at lower pressure. For Bezzera machines, they are usually tuned to work at around 12 bars. The other purpose of the OPV is to dampen the pulses of pressure from the vibration pump, so the flow will be smoother and creates less channelling issues.

Rotary pumps are used in places where usage level is high. They weigh several kilograms, slightly bigger than the size of two fists. They are split into two parts, the pump and the motor. 

Rotary pump moves water by rotating the vanes in the pump, similar to how a fan moves air. They are capable of transferring a larger volume of water very quickly and are set working at lower pressure of about 10 bars. If you need to make adjustment of pressure, normally there’s a control which you can access externally from the machine that tune the pump directly. User should not tune the pressure above 12 bars

There is still an over-pressure valve for the rotary pump, which should not be tuned. It is not for controlling the pressure but as a safety to vent off excess pressure and regulate water flow. 

Difference in extraction?
There shouldn’t be much difference in the extraction or the taste. If we want to pinpoint to something. The vibration pump has a slower ramp-up of building pressure. This can unintentionally increase a bit of pre-infusion which can be good or bad depending on the type of coffee used.

Difference in durability?
Vibration pumps have a duty cycle, that is how long they can work before you need to off it and let it cool down. For prosumer machines sold by us, it’s 2/1. For every 2 minutes of work, it has to rest for a minute. The typical lifespan for vibration pump is usually 5 years and are normally damaged by users who let the pump work for too long for various reasons. They are not recommended to be used in environment where usage is high or with users who may abuse the machine. One big advantage of vibration pump is they are much cheaper to replace so it won’t pinch as hard when you decide to breathe a new life in them.

There’s almost no duty cycle for the rotary pump and they can last much better with lesser issues, partly is because they are not as dependant on the over-pressure valve to regulate pressure. They are the best choice if you are intending to use it in an environment with heavy usage. This does not mean that the pump is indestructible, rotary pump can overheat and burn itself out if the supply of water is cut and it runs empty loaded. Rotary pump cost at least 3x more than vibration pumps when they are needed for replacement.

In both types of pumps, they can be damaged by limescale so using an efficient water softener is always the most important step.

Using harsh chemicals to descale the machine can sometimes cause erosion and does permanent damages. This is especially so with vibration pumps, that’s why we see a higher tendency of machine failure after descaling. Also, both types of pump may have to be primed after a period of idling or for a new machine.