About Espresso Machine Types

This is a post I wrote for a coffee forum in September 2013
I thought I would start this for those who are thinking about buying an espresso machine, or have just purchased their first espresso machine, or have a machine but are thinking of upgrading to something else.

This is not intended to be an all encompassing document, only to provide some basic information about how the different types of espresso machines out there work. I encourage other B&B members to add to the information in this post.

Just like with anything, it is the person operating the tool that makes it happen. Don’t get discouraged if the first 10 or even 20 cups you make taste like mud. You need to understand the concept of making espresso and how your machine works before you can get a perfect pull time after time just like you need to understand how any job is performed time after time.

Patience. Practice. Consistency.

Do the same things consistently over and over will get you a perfect espresso pull every time.

Espresso Basics: (basics that will be the same no matter what type of machine you have.)

  • It takes time for your espresso machine to come up to a stable temp. It may only take 60 seconds for the water to get hot enough but it may take as long as 1 or even 2 hours for the entire machine (boiler, head group, and portafilter) to get to a stable temp where your pulls will be perfect and consistent so BE PATIENT. Each machine is different and will require a different amount of time to come to a stable temperature based on the size of the boiler and the construction of the head group. Learn now long your machine needs to be turned on before you can make good pulls and always wait until your machine is ready before you start. If you want espresso before you go to work, get an industrial timer and have your machine come on at least an hour before your alarm goes off.
  • Find a local coffee roasting house near you and buy your roasted beans in small batches. The “flavor window” on roasted beans is between 3 and 14 days so don’t buy more than you can consume in a week or two, even if you have to buy a half pound at a time. Beans younger than 3 days are going to be gassy and need time to rest after roasting to be at their peak flavor. After 12 days the crema produced will start to decrease and the taste will start to change shortly after 2 weeks pass so use ONLY freshly roasted beans. If you do not have a specialty roaster near you, you can buy online but shipping will make this more expensive. You can buy green beans and roast at home in small batches in a frying pan on your stove top if you don’t want to invest in a coffee roaster. The beans you buy at the grocery store have been treated for long shelf life and will not have the flavor and taste that beans you get from a local specialty roasting house will have.
    Coffee has what is know as the rule of 15’s. Fresh harvested beans are good for 15 months after harvesting before they must be roasted. Roasted coffee beans need to be consumed within 15 days after roasting. Ground beans need to be brewed within 15 minutes of being ground. Espresso needs to be drunk within 15 seconds of being brewed.
  • Weigh your beans and always use the same weight of beans for each volume of water you use. Typical weights and volumes are: 7 grams of ground beans to 1 oz of water is considered a “single shot”. 14 grams of ground beans to 2 oz of water is a “double shot”. There are larger baskets that will allow you to make triple shots which would be 20-22 grams of grounds to 3 oz water. This is just a “rule of thumb”. Personally I like heavy shots so my double is 18 grams of ground beans to 2.25 oz water. Start with the “rule of thumb” beans/water ratio and work up or down to YOUR taste.
    When you first start out, use a 2 or 3 ounce shot glass (marked in 1/2 oz graduations) and pull your shots to volume in the shot glass. After time and with some experience you will know when your pull moves from crema to blond and you will know when to stop but until you are to that point…. weigh your beans and measure your water (remember, be consistent)
  • Use good water. If your local water supply is high in mineral content or does not taste good, your espresso will not come out as well as it could. Use a water filter and softener if you are on a well or your local water supply is not good. I won’t go into what to use as there are so many options available but find something that will give you good tasting water and a reasonably low mineral content, or use bottled water. Remember you are only using a few oz of water so even if you must use bottled water you will not be spending a lot. Don’t use distilled water as you need some mineral content and distilled has none of the good things you want in your brew water.
  • Get a GOOD espresso grinder. Your espresso will only be as good as the ground coffee you use. If you are going to spend big, do it on the grinder. A good quality espresso grinder and an inexpensive espresso machine will make better tasting shots than an ok/average “coffee” grinder and a very expensive espresso machine will make so DO NOT skimp on your espresso grinder. If you can’t afford several hundred dollars for a high quality espresso grinder get a high quality hand espresso grinder and spend 2-4 minutes grinding your beans by hand.
  • Espresso machines brew under a pressure of 9 bar (130 psi) so treat your machine with respect. If your machine does not have a 3 way valve to release pressure at the portafilter when the shot stops, WAIT 1 to 2 minutes before removing the portafilter from the machine to avoid getting sprayed with very hot water and coffee grounds.
    The steam in the boiler is produced by super heated water (300 +/- degrees) and the steam coming out of the wand tip can be over 1200 degrees. Always remember this and don’t get lax around your machine. Keep children away and keep the machine out of reach of small children (and some adults)

Types of Espresso Machines (what’s inside)

Single Boiler Dual Temperature: This type of machine makes up the typical entry level home machine range and more than likely, this is the type of machine you will end up purchasing for your first espresso machine. As the name implies they have a single boiler that is dual purpose (brewing and steaming). Typically these type of machines have smaller boilers which helps them switch between the brew and steam function faster as both functions require different temperatures. There will be a switch or button to engage either the brew temp or steam temp function. Brew water should be between 195 and 205 degrees and steam water can reach up to and sometimes over 300 degrees when under pressure. You can see the conundrum. Water in the boiler cannot be 200 degrees to brew coffee and 300 degrees to produce steam for frothing milk at the same time. Each process required to make a latte or cappuccino (brewing and frothing) with a dual temperature machine needs to be dealt with separately. This can be done by either making your pull first then switching on the steam function and waiting for the boiler to reach steam temp then frothing your milk OR frothing your milk, turning the boiler back to brew function and running some of the boiler water through the empty portafilter to lower the temp back down to brew temp (below where the boiler needs to turn back on to get back to brew temp). Either method should work but you will find those in the espresso world who will argue that one way is better than the other. Use which ever method is the most comfortable and quickest for you and you will be fine.

Pressure Basket Machines: Some of the entry point single boiler machines will come with what is known as a “pressure basket” or “enhanced pressure portafilter” These machines use a rubber or metal disk/gasket and plug or springs in the portafilter to help slow down the extraction time and to develop enough pressure to make the extraction. Machines with pressure baskets can use standard grocery store drip grind coffee all the way to espresso grind. They do not require the coffee to be tamped so what is said in here about espresso making technique and methods will not pertain to this type of machine. This is not said to talk down about this type of machine and in fact someone new to espresso will get much better results with a pressure basket machine than they will with a machine that requires barista skills as they take “the espresso grind quality and the tamp pressure” required by standard espresso machines out of the brew equation. They are a “bullet proof” way of making espresso which just requires dumping in grounds, attaching the portafilter, and pushing the button to make espresso. They will constantly make half way decent espresso with any type of coffee and with almost no knowledge or assistance from the operator. Unfortunately you will not develop coffee making skills with this type of machine. Most pressure basket machines are set up so that the disk/gasket can be removed, then the machine can operate like a normal espresso machine as this type of device is an add on to the portafilter, not a modification of it. The purpose of the enhanced pressure portafilter is to eliminate the requirement of using an espresso grind coffee and properly tamping of the grounds so that the machine can be used with any type of ground coffee and give the same results.

Single Boiler Heat Exchanger (HX): Heat exchanger (HX) machines are your typical commercial type machine and are found in most espresso bars, coffee shops, and restaurants. They have a single boiler to make steam for frothing milk. The brew water runs through the boiler in a separate tube or chamber (the heat exchanger) where it picks up heat from the boiler before being sent to the brew head. These machines have pluses and minuses. They usually have a large boiler and can continuously provide steam for frothing milk at the same time the brew water comes through the boiler in its separate pipe to be heated so the operator can brew and steam at the same time with near perfect temperatures in both functions. HX machines are geared for larger production such as a coffee shop where 100 cups an hour are typical and demands of 150 and more cups an hour at rush times are not uncommon. These type of machines can keep up with this demand and are only limited by the size of their steam boiler and how many group heads are on the machine which will only effect the number of cups per hour the machine is capable of producing.

Heat exchanger machines have become very popular in the “prosumer” line of machines. These are machines that are for home use but have larger boilers, larger water reservoirs, use commercial parts, and have a commercial look. Home HX machines are designed to run on normal house current (110 volts) instead of the 220 volts that commercial machines are designed for. They will normally have a larger refillable reservoir, a 15 bar vibration pump, a 2 way valve for refilling the boiler, and a 3 way valve to send brew water to the head and relieve pressure from the portafilter after the shot is completed. Some HX machines come in direct plumb models (water piped in and the drain piped out) with rotary pumps. These type home machines are identical in design to a 220V commercial machine.

The draw back to HX machines is that the brew water will super heat if pulls are spaced out more than 3 or 4 minutes apart. This is not a terminal failure but the operator must preform a “flushing” pull to purge the exchanger of the overly hot water and flow cool water from the reservoir into and through the exchanger to the brew head so that the temp stabilizes back to the 195-205 degree level for making espresso. A typical cooling/flushing pull is 1 -2 minutes. With my HX machine I wait until I see the “happy dance” (where the water comes out uniformly all around the group head screen), then attach the portafilter and make my pull.

Dual Boiler Machines: As the name implies, these type of machines have separate boilers for producing steam and for producing brew water. This would appear on the surface to be the best of the best as each process has its own boiler. Well it is. If there is a draw back it is the higher current demand of these dual boiler/burner machines. A typical single boiler “prosumer” home HX machine will draw between 1200 and 1500 watts whereas a dual boiler machine if it is to be effective must draw more which can tax household wiring. Some dual boiler machines need a 20 amp circuit. Some even “suggest” a dedicated 20 amp circuit for the machine alone. Many dual boiler machines for the home market are compromises and have a large steam boiler and smaller brew boiler so that they draw a reasonable (and safe) amount of current and do not over heat home wiring. Some of the newer home dual boiler machines have separate switches so that either boiler can be turned on/off independently.

Unlike an HX machine or a dual purpose single boiler machine, dual boiler machines are two separate machines in a single housing so brewing and steaming can be done simultaneously without any special “dancing” by the operator. You do pay for this as dual boiler machines are some of the more expensive type of espresso machines on the market.

Styles of Espresso Machines (how they work)

Manual Espresso Machines: The manual machine is easily spotted as they will typically have a lever sticking out the front of them. They do not have a pump to provide portafilter pressure or to refill the boiler. The pull and boiler refilling are both manual tasks and the responsibility of the operator. The boiler must be stone cold before removing the top to refill it which can be a problem if you are making shots for a group and run low or out of water. The manual machine is the most difficult to master as the operator is charged with every aspect of running the machine from maintaining water levels in the boiler, to selecting the boiler function (brew or steam), to applying the proper pressure with the lever for a perfect extraction. You may not get one of these machines as your first espresso machine so I will not go into detail about their operation other than to say they are almost always single boiler dual temperature machines. You must be a true barista to know how to “feel” the pull. Some people spend years with a lever machine and only get an OK pull. Others fall right at home with one and would never consider anything else.

Semi Automatic Espresso Machines: Semi automatic machines have a pump to both fill the boiler and to provide brew pressure to the portafilter. They will feed the boiler from a reservoir (or direct plumbing) and when the brew function is switched on will pump water under pressure to the brew head for as long as the switch (or lever) is engaged. Semi automatic machines will have some form of “computer” to control the boiler temperature, boiler pressure, boiler fill level, two way and 3 way valving, and pump on/off function. The operator is tasked with watching the pull and knowing when to stop it. This allows for someone with experience to get a perfect pull just from watching the brew coming out of the portafilter. If you do not know what you are looking at, use a shot glass and measure until you get to the point of knowing what each stage of the pull looks like.

Automatic Espresso Machines: These are semi automatic machines with one difference. The duration/volume of the pull is computer controlled and programmable. The internal operation of an automatic is identical to the semi automatic. There will be a control panel with buttons for single shot, double shot and manual on/off (some have more program options). The shot buttons are programmed once and every time one is selected the exact same amount of water flows through the portafilter. Once set up to the correct water volume an automatic machine will perform exactly the same pull time after time as it is only running its program when started. All the operator is tasked with is attaching the portafilter and selecting the correct button. The machine does the rest. An automatic machine can operate like a semi automatic by selecting the brew on off button instead of one of the programmed options

Super Automatic Espresso Machines: The super automatic does everything. Grinds the beans, makes the pull, froths the milk and adds it to the cup. All the operator is tasked with is making sure that the machine has coffee beans, water, milk, and a cup under the spout to accept the finished product…. The only thing you need to do is select the type of drink you want to have (single or double espresso, latte, americano, cappuccino, risotto etc) and press the start button. The machine does everything for you, grinds the beans, tamps them, pulls the shot, froths the milk and assembles it all in your cup. Super automatic machines are perfect for someone who wants a great cup of espresso or a frothy cappuccino but does not want all of the bother associated with making one.

This is just the tip of the iceberg. There is so much more that needs to be known about water quality, coffee beans, grinding, tamping, frothing, and extraction time. Make sure you tamp to 30 psi. Make sure your tamp is level. Remember to flush the condensation out of the steam wand before you start to froth your milk. There are other tricks you can work into your routine once you get the basics down like pulling a short 1-2 second pre-infusion shot before you pull your full shot.

I’m off to make another americano so ya all have fun, keep at it, stay constant, and enjoy your experience with espresso making

Oh and don’t forget to practice your latte art when you have a little free time