HI;

I'm reading lots of different things and am slightly confused. Do all types of machines have to be flushed before pulling a shot?

I member told me in a thread about buying advice that the Bezzera BZ02 needs to be flushed about 2-4 seconds, which sounds easy enough to manage.

Then I read this http://www.home-barista.com/hx-love-manage-brew-temperature.html and it makes it sounds much more complicated to hit the right temp.

I though a big part of the reason for using a HX machine was that the brew and steaming water are kept separate so the brewing water doesn't over heat.

My fiance has to be able to use the machine as well, and she is not going to be willing to do much timed flushing / temperature surfing.

So if my fiance doesn't flush long enough or forgets to flush between shots, are the shots going to be totally ruined? (the way they are on a single boiler machines is you try to pull a shot after steaming without flushing).

Hope that makes sense.

Thanks

Jamie

jamiedolan wrote:I though a big part of the reason for using a HX machine was that the brew and steaming water are kept separate so the brewing water doesn't over heat.

Brew/steaming water separate = double boiler machine

A HX machine uses one boiler, hence the need for flushing. A double boiler machine may or may not need a flush, depending on grouphead design (supposedly my GS3 has a saturated grouphead and is always at temp, while an E61 double boiler isn't fully saturated and could use a flush to equalize everything).

For what it's worth, I typically flush on the GS/3 just to get the portafilter all hot and clean - it's fun .

With an HX machine, yes, water used for brewing and that which is heated for steaming, ARE kept separate. But, not in the same way as a dual boiler is.. which is simply two different boilers.

In an HX machine, there is one boiler. Most of popular choice HX machines have a boiler that is under or around 2.0liters. Larger HX machines, like the Elektra A3/T1 or the Cimbali Junior have bigger boilers. But, the design is the same. The boiler is kept about 2/3rds full of water. The water is heated to steaming temps, ~240F. Once the boiler is hot, it can steam all the milk you need for daily use in the home. Water used for brewing, comes from the reservoir tank, OR, direct from your homes water supply, depending on whether or not the machine uses a reservoir, or is plumbed in. When you brew espresso, water is pumped from the reservoir, through the heat exchanger(the HX), and out the grouphead/through the portafilter. The HX is a tube which runs through the boiler, and is immersed in the water. The water which is heated to ~240F in the boiler, heats the water running through the HX to brewing temp.

When the machine is on and left to idle, the water sitting in the HX tube will heat to basically the same temp as the water in the boiler. So, after a long idle period(like the hour that the machine sits while it heats up), you need to flush about 8oz or so through the group. This refreshes the HX tube with water from the reservoir which is roughly room temp. Now you can make espresso.

Yes, before you make espresso, you need to flush water through the group. And this part right here is what we have spent MANY, many threads discussing. It is also one of the main points brought up in the debate of HX vs. DB machines. Basically, you can get as technical as you want with this. You can install the thermometer in the E-61 group to monitor water temp, you can time and measure your flushes, and much more. OR, you can simply flush the group while counting to say, 8, and then make your coffee.

When you first get your machine, if its an HX, you will need to learn the machine. You will need to figure out how much water you should flush and how long you should wait after flushing(if at all) before you pull your shot. Once you have that figured out, you can alter it for "hot" "medium" or "cold" shot temps. IF you desire precise knowledge of your brew temp, you wont get that with an HX. However, what you WILL certainly get from an HX, is great espresso.(Granted you use a good grinder and high quality, fresh roasted coffee)


All this sounds real complicated Im sure. But trust me, as a former HX owner, once you get the machine in front of you and figure out a couple simple flushing routines, it can be a piece of cake. Many people simply flush water out of the group while counting to, say, 5seconds(or whatever), wait 10seconds(or whatever) and pull their shot. Describing how to make espresso using an HX machine is the most complicated thing you could think of when it comes to brewing coffee. Actually USING an HX machine is far simpler.

Is using a Dual Boiler simpler? Yeah. Is it better? Depends on you. However, Dual boilers still need to be flushed, some cases more so than HX machines. However the flushing with a Dual Boiler is mindless, whereas the HX, in the beginning at least, requires a little thought.

Jeff brings up a lot of good information in his post, but I don't think he answered one of your questions. On a lot of HX machines, you do not need to flush in between shots if you pull them back to back. I guess the more technical answer is that you can adjust the temperature so that you don't need to flush between shots. After a long rest, a shot might not be totally ruined without flushing, but it would be very bitter.

Commercial and semi-commercial espresso machines are typically designed so that one shot can be pulled from each group each minute. The heaters, boilers, heat exchangers, and groups are all sized for this routine. How they will behave after longer idle periods depends.

In a traditional HX machine, the design goal is for the group to cool off at the same rate as the HX water heats up when the machine idles, so shots can be pulled without flushing. In most home HX machines, they cut corners and this level of tuning is not achieved. Even if it is, the shots will taste slightly different, and consist taste requires some flushing.

In a double boiler machine (and an old style lever), the group cools off while the boiler water remains the same. This will mean that these machines should be given a quick flush. In the most recent DB machines, the feed water to the brew boiler is preheated, and some use tricks to keep the head very stable, or to run the brew water a tad hotter after a long idle.

But while this answers your questions; it does not help you. Beginners tend to obsess about machine temperature, when they should obsess about their own skills instead. Skill in espresso means getting a few dozen things roughly right, not two or three things completely perfect. So once you have any sort of reasonable flush, 99% of your lousy shots will be due to ignoring all the other things to which you should be attending in the quest for perfect temperature control.

A big Thank You to everyone here for the excellent explanations.

JmanEspresso wrote:Once you have that figured out, you can alter it for "hot" "medium" or "cold" shot temps.

This is the one part that I am not following; once you have run the flush, wouldn't the temperature be stable as it continues to pull water through the heat exchanger? I was thinking of the heat exchanger like a instant hot water heater (only with the boiler acting as the heating element), where once it is on and running, it keeps giving you water at the same temperature.

I don't quite follow how you can alter it to "hot" "medium" or "cold", Does the heat exchanger act more like a mini-boiler where it has a capacity, then once emptied needs to re-heat?

JmanEspresso wrote:IF you desire precise knowledge of your brew temp, you wont get that with an HX.

I don't care if I know the precise brewing temperature, that really isn't important to me. I'm much more concerned about it being reasonably easy to operate and reasonably easy to produce fairly consistent results. When I have time, I don't mind playing with it, and adjusting things to improve my shot quality, but there are days where I just want it to work and make me a reasonable quality drink without a lot of hassle.

JmanEspresso wrote: However, what you WILL certainly get from an HX, is great espresso.

That is what I needed to know, that this will work well.

JmanEspresso wrote:Describing how to make espresso using an HX machine is the most complicated thing you could think of when it comes to brewing coffee. Actually USING an HX machine is far simpler.

From the things I read, and some of the videos I watch, they can make the process seem extremely complex; it's hard for me to know if they are adding some of these complexities out of necessity or if it is just them trying to tweak out the perfect shot. I'm starting to gather that it is more of the latter.

JmanEspresso wrote:(Granted you use a good grinder and high quality, fresh roasted coffee)

another_jim wrote:But while this answers your questions; it does not help you. Beginners tend to obsess about machine temperature, when they should obsess about their own skills instead. Skill in espresso means getting a few dozen things roughly right, not two or three things completely perfect. So once you have any sort of reasonable flush, 99% of your lousy shots will be due to ignoring all the other things to which you should be attending in the quest for perfect temperature control.

I have a Mazzer Mini E doserless for a grinder. I've used it to pull quite a few shots on the cheap-o espresso machine I have now. I think I've got a pretty good feeling for grind adjustment, tamping, dosing. With the machine I have now, it was pretty much a "guess n' pull" in regards to the temperature, with times the shots would turn out quite well and (many) other times now so well. I wanted to make sure this new machines gave me enough stability, that I wasn't going to have to play guessing games with the temperature.

I was at SCAA a couple of years ago, so I got to watch a lot of people making espresso and steaming milk correctly. I do hope once I have a good machine, I'll be able to start pulling (reasonably) good shots pretty quickly, assuming I understand the little "quirks" of the machine I get.

I've roasted with the Iroast with most of my beans from Sweet Marias. I also have a RK drum that I use on the grill. I'm thinking about getting a Behmor when I can; I'd really prefer to roast inside in the winter months, and the Iroast has seen better days.

Thank You;

Jamie

jamiedolan wrote:I don't quite follow how you can alter it to "hot" "medium" or "cold"

You just have to keep in mind that the difference between hot and cold is only ~6 degrees F.

Water runs through the middle of the boiler to pick up a lot of heat. The group head has a lot of thermal mass, so it "fine tunes" the water temperature after the primary heating inside the boiler. But obviously this system wouldn't work for any incoming water temperature - ice water still wouldn't get hot enough with one pass, for instance.

So, if you flush a fair amount water, the components inside the boiler all start to cool off (a relatively small amount), and the fine tuning of the group head isn't quite enough to get the water to 200 or whatever you are shooting for. If you flush a lot, even the group head starts to cool off a bit, and exiting water is even cooler.

jamiedolan wrote:Does the heat exchanger act more like a mini-boiler where it has a capacity, then once emptied needs to re-heat?

Yeah, kind of. In its intended use of pulling a series of shots, however, it has "infinite" capacity.

It states in my La Cimbali manual that my machine is rated at 120 shots/hour, so you could say that it's almost an infinite supply of hot water. That said, in the morning, it's a good idea to flush some water to heat up the group head and portafilter holder, and after it's sat idle for a while, it's a good idea to do a bit of a cooling flush to get the hx water down to brewing temperature.

You have done the right thing by reading the HX Love article. If you do end up getting an HX machine, re-read it again and try out its suggestions. Then practice them for a while. It's really just not that difficult. Time your flush after the water dance ends and dial in your temperature. It's like dosing your shots. At first you get all anal about weighing each shot, but after a while you just get a feel for it. For your wife, you can just write the procedure down (turn on machine, wait x minutes, flush for x seconds, dose, short flush for x seconds, lock, load and pull for x seconds - not that difficult - of course, I just spent 15 minutes on the phone walking my wife through sending an email at her work place, so if she's like my wife, this might not work!)

darilon wrote:I just spent 15 minutes on the phone walking my wife through sending an email at her work place, so if she's like my wife, this might not work!

LOL

This is the reason I'm going to order the automatic model. If it was just me, I'd get the semi, but she is really bad at timing shots, and I doubt she will bother to use a timer. I'll likely just use it in manual most of the time.

I'm placing my order this afternoon. Really looking forward to this.

Thanks
Jamie

My addition to this is that a lot will depend on her tolerance for what good espresso is. I am unfortunate in that I have a very small window of tolerance for what I consider "good" yet I'm unable to properly discern bitter from sour. I only taste bad or good. Erics's thermo adapter has made adjusting somewhat easier, however even when my routine ducks are in a very nice row I still only rarely taste "good". I know I'm not doing anything particularly wrong because I get about the same frequency of good/bad shots at many of the local, world class espresso houses. What kind of drinks is your other half making? If she's into espresso shots and wants a low "fiddle factor" then this may not be a road you want to go down. If she's making milk drinks I think she'll probably be alright. Who knows, maybe like me she'll enjoy the challenge of constantly chasing the perfect shot. Or perhaps not.