HX vs DB

by **Juanjo** on Fri Jun 05, 2009 2:48 pm

Hi,

here is something I'm pretty clueless about..

FOR HOME USE.
the size of the boiler is more about steaming that for the espresso making... right!!

here is my question:

what's "better":
a DB let say 1.8liter for steaming / .8liter for brewing
or
a HX 4+ liter boiler?

in other words,
two small boiler or a BIG one?

thanks and sorry for my cluelessness

Juanjo

by **JohnB.** on Fri Jun 05, 2009 3:17 pm

One benefit of a well designed DB is that you can turn off the steam boiler when you don't need it so you are only heating a small brew boiler. Also the small brew boiler should respond quicker if you want to raise or lower the brew temp.

by **Juanjo** on Fri Jun 05, 2009 3:28 pm

Thanks John,

the water wand on a DB is connected to the brewer or steam boiler?

the raising and lowering the brew temp have a lot to do with the heat element..right!
I have a 4.5liter boiler with 1850watt heat element and the temp raise very fast.. within seconds.

anyway.. I'd like to know more about the two..

thanks again,
Juanjo

by **Bluegrod** on Fri Jun 05, 2009 3:36 pm

A big factor in choosing which to get is what kind of drinks you make more often. If espressos are your thing than a double boiler is really not that important. If you like alot of milk based drinks than maybe a double boiler is your best choice. Just for your information I like a combo and usually have 2 espressos and 1 cap per day. I currently have a quickmill vetrano which is a 1.6l HX and it's an excellent performer. We do have people over on a regular basis and during that time I might make 3 to 4 milk based drinks at a time and the vetrano will keep up with the pace for that many drinks with no problem. I guess you just have to decide what you drink more of and start to work from there.

by **MDL** on Fri Jun 05, 2009 3:55 pm

Every double boiler machine that I know of uses the brew boiler only for the group head to pull shots. The steam and water wands are connected to the steam boiler.

I don't know of any reason to want to regularly alter the steam boiler temperature. Different coffees taste different/better when shots are pulled at different temperatures. With a double boiler machine you can change the brew boiler temperature relatively quickly because the brew boiler is relatively small.

With HX machines the relationship between the boiler temperature and the brew temperature is more complicated.

I use a double boiler machine and love it. I don't have to do any temperature surfing and I can steam as long as I have ever needed to. As John said, you can also turn the steam boiler off if you don't need it.

Take care,
Mark

by **Juanjo** on Fri Jun 05, 2009 4:30 pm

thanks again,
so unless is something more than steam power, which in my experience with 4 HX machines from 1.2 to 4.5 liter boiler was endless.. the biggest plus of the DB is that you can switch off one boiler.. right!

Juanjo

PS.
if you don't steam a lot the water on the steam boiler doesn't get "old" causing scale..! do the machine rescale that or you have to do it manually (or NON and I'm talking out of my $#%

)?

by **JonR10** on Fri Jun 05, 2009 5:28 pm

Juanjo wrote:the biggest plus of the DB is that you can switch off one boiler.. right!

I would disagree. I'd say that the big advantages of the DB is more precise control over brew temperature and removing the need to purge an overheated HX tube. With practice on the HX, you can repeatably produce brew temps within a reasonable window but with a DB you can nail a specific flat-line brew temperature every time (a specific temp - like 201.5°F or maybe 194.0°F)

Juanjo wrote:if you don't steam a lot the water on the steam boiler doesn't get "old" causing scale..! do the machine rescale that or you have to do it manually (or NON and I'm talking out of my $#% )?

Since there is very little need to refill the steam boiler, many folks I know use very soft water (or maybe even distilled) so scale isn't a problem.

by **Vad** on Fri Jun 05, 2009 5:36 pm

I agree about steaming. If you will do a lot of milk drinks, go for a 4 liter HX. I myself own one, and it is great (after I got to know it well).

by **timo888** on Fri Jun 05, 2009 5:37 pm

juanjo wrote:the biggest plus of the DB is that you can switch off one boiler..

No.

The biggest plus of the DB design is that brewing is independent of steaming. Steam requires superheated water. If the brew water is drawn from, or through, the same boiler that produces steam, the water is much too hot for espresso and needs to be cooled, using a large brass heat-sink. With a DB, the brew water can be heated to the desired brew temp (or just a couple of degrees above it to compensate for loss) and so there is no need for a heat-sink. The lack of a heat sink and the typically smaller volume of the brew kettle on a DB means the temperature can be changed readily, because there is no large thermal mass to deal with. Changes can be precise, too, whereas with an HX, whose temperature is regulated by flushing, there is far less precision, and moreover, the HX is only at that desired temperature range after flushing for a brief time, as it will quickly rebound.

by **Juanjo** on Fri Jun 05, 2009 5:48 pm

did a little search and find this..
http://blog.seattlecoffeegear.com...double-boiler.html

my HX SanRemo Capri is RIGHT ON with the temperature.. espresso after espresso, cappuccino after cappuccino.. maybe I'm lucky but never had a temperature problem with my HX machines.. (well, maybe a little with the first one, livia90)

by HB on Fri Jun 05, 2009 5:56 pm

Also see Some thoughts on heat exchanger vs. double boiler espresso machines for an interesting discussion of many of the same points raised in this thread.

by **JonR10** on Fri Jun 05, 2009 6:18 pm

Juanjo wrote:my HX SanRemo Capri is RIGHT ON with the temperature.. espresso after espresso, cappuccino after cappuccino..

First question - What does "RIGHT ON" mean to you? What temperature do you brew at?

Second question - What if you are using a blend that brews best at 201-202°F this week, but next week you switch to something that brews best at 185°F and the following week you need 196°F? Can you accurately and repeatably hit all of these temperatures with your HX?

After a few years of practice on my machine, I can get "high" and "lo" easily but precision switching requires alot of effort (with practice and measurement).

by **Juanjo** on Fri Jun 05, 2009 6:26 pm

"RIGHT ON" is the perfect temperature for ME to enjoy my espresso to the fullest..
don't think I got to the point of one bean for this and one bean for that temperature..
AND to be honest doubt I'll EVER be.. :oops:

by **JonR10** on Fri Jun 05, 2009 6:40 pm

Dude

Lighter fruitier blends brew better at higher temperature (in general)
Deeper chocolate comfort blends brew better at lower temperature

Example:
I have a lovely DP Ethiopian that I roast light to keep it's fruity notes. This makes a lovely fruited espresso at around 201-202°F. At 192°F it's terrible (sharp and ascerbic, sour)

Some of my favorite espresso is chocolate bomb ristretto made from Yemen beans roasted into second crack and rested at least a week. I prefer to brew this coffee at around 192-194°F, but at 202°F it loses the sweet-chocolate-bomb effect.

Honestly, you may not really even know if you are enjoying your espresso "to it's fullest" until you can accurately measure and repeat different brewing temperatures and understand how this affects the taste of your shot. There is a wide flavor spectrum across a 10°F spread of brewing temperature.

by **1st-line** on Fri Jun 05, 2009 6:40 pm

Juanjo wrote:Hi,

here is something I'm pretty clueless about..

FOR HOME USE.
the size of the boiler is more about steaming that for the espresso making... right!!

here is my question:

what's "better":
a DB let say 1.8liter for steaming / .8liter for brewing
or
a HX 4+ liter boiler?

in other words,
two small boiler or a BIG one?

thanks and sorry for my cluelessness
Juanjo

In general, the HX machine will have more steam power AND capacity which helps in cases where more milk-based espresso beverages are made. In the double boiler scenario, the machine will have an increased stability in the espresso brew temperature control which helps in cases where more espresso only beverages are made.

It is subjective whether one will see the improvement in consistency of the espresso in a milk-based beverage when using a double boiler machine as the quantity of milk can dilute the espresso.

On the surface, the double boiler should save energy. However, I do not see any studies proving this point. The reason is that the PID controller is constantly assessing the temperature and sending power to the heating element more often than the HX machine. Yes, maybe there is less wattage being consumed, but IF the double boiler is sending power 'double the time of power on' to keep a constant temperature, this may be a wash. I do not have any evidence to prove either way.

Finally, distilled water can not be used in a HX or double boiler machine where there is a water autofill probe that relies on 5 volts of electrical current to run through the probe, through the water, and to the boiler wall (ground). The auto refill circuitry senses that when electricity passes through to ground, there is enough water in the boiler. When the water level drops, there is no electricity passing through, and it activates the pump and electrovalve to get more water to the boiler. With distilled, the auto refill circuitry will overfill the boiler.

by **malachi** on Fri Jun 05, 2009 6:43 pm

I'd suggest using the Search function.
This particular topic has been covered at length.

As commented on above - by dedicating a boiler to brew water (and divorcing it from the needs of steaming) it is easier to run a range of set, specific and stable brew temperatures while also having a steam boiler at optimal pressure, water fill, etc.

by **timo888** on Fri Jun 05, 2009 6:54 pm

Juanjo wrote:did a little search and find this..
http://blog.seattlecoffeegear.com...double-boiler.html

my HX SanRemo Capri is RIGHT ON with the temperature.. espresso after espresso, cappuccino after cappuccino.. maybe I'm lucky but never had a temperature problem with my HX machines.. (well, maybe a little with the first one, livia90)

You do not encourage detailed responses to your inquiries when you communicate in vague generalities such as "had a temperature problem".

No one's talking about "problems". We're talking about the differences in the two basic designs, double-boiler and HX, and their respective strengths or benefits. If I were a caterer who served guests at corporate retreats, where the throng had to be served milk-drinks back-to-back, I'd pick an HX machine. If I were a home-barista, who liked to try different roasts and blends and SOs, I'd choose a DB. If I were a home-barista with no desire to experiment with the effects of temperature on the beverage, well, I'd probably say that my machine never gave me any problems, whatever machine it was.

by **Juanjo** on Fri Jun 05, 2009 7:17 pm

Dude..

fullest to ME...

I roast my beans weekly, and grind them seconds before the extraction...
believe me, so far non of my friends or anyone who try me espresso have any complains about it.. actually I get very good complements..
sorry if I'm not geek enough for some people standards..

anyway..
THANKS A LOT for all the replies..

Juanjo

by **JmanEspresso** on Fri Jun 05, 2009 7:21 pm

What was said about certain coffees liking much different temps, is where the DB shines, I THINK.

I have a HX, setup with Erics grouphead Therm. With that, it is definatly easiER to hit "low" temps and "high" temps, but, as Jon said.. Hitting the exact temperature you want is no easy feat, even with the grouphead therm.

Most, if not all, HX machines, whether it be the smaller Quickmill/Vibiemme etc, or the larger Elektra/La Cimbali HX's, are all dependent on the Pressure-stat.. Which controls boiler temps. At any given setting, the machine "wants" to run in a certain temp range. So for pressure-stat setting "x" you can hit shot temps in a certain range, maybe of 4-5 degrees. It IS possible to hit temps higher or lower then the "range", but then you run the risk of the temperature profile becoming wildly distorted, as the machine doesnt "want" to pull shots at that temp. IE: Yes, you can just flush a WHOLE LOT of water, have a short rebound, and pull the shot, but the temperature isnt going to be nearly as stable, the grouphead can be too cold/too hot, the HX water can be too cold from the tank, and a whole mess of things that Im not qualified to truly discuss because of knowledge, or lack thereof, can happen.

BottomLine: The pressure-stat setting of an HX machine determines you're "range" of temperatures that you can easily and consistently hit. Going much higher, or much lower, with any consistency/repeatability, would really require a pressure-stat change.. And everyone knows thats not something to do multiple times a week.

And this is why, to me, Dual-Boilers really shine. **Pretty much all the DB's that are popular on the market today have the BREW boiler PID'd. Some have the steam boiler PID'd as well**. That means, NO Pressure Stat. The temp you set in the boiler, is the temp you want to pull your shots at. No "flushing methods" are required, other then a quick, say 2-4oz flush after a long idle to bring the grouphead to temp. Changing temps also does not require long flushes either.. Just plug in the temp you want on the PID controller, wait roughly 5mins+/-, and you're ready to go. Need to change it again? Plug it in, wait 5mins+/- Pull/taste/evaluate.

Now, this is just my personal opinion, but I really think that in the next few years, double boilers are going to become the standard in the "pro-sumer" and "semi-commerical" market. They are more or less standard in a commercial cafe setting.. Yes, lots of places still use HX systems with great success,, But I think we could all agree that the margin of error, and amount of training goes down, while repeatability and consistency go up. In the home setting, DB's translate to less sink shots because of temperature.. Allowing us to somewhat eliminate one variable from the equation.. which is always nice.

In the "for what its worth" area, Ive owned my HX for roughly four months..ish. I do really like my machine, but I already have passed the thinking stage, and am currently on the researching/shopping/saving stage of upgrading to PID'd Dual Boiler machine.

**Not ALL Dual Boilers are PID'd. The new VBM Junior DB isnt PID'd

by **1st-line** on Fri Jun 05, 2009 7:47 pm

What was said about certain coffees liking much different temps, is where the DB shines, I THINK.

On the flip side, certain coffees 'may' like the small swing in temperature during a shot. The following could be examples:

a) Start with a lower temperature and graduate to a higher temperature
b) Start with a higher temperature and graduate to a lower temperature
c) Have a bell curve temperature change

I have experienced a and b with positive results. C is the one I have a challenge accomplishing.

As a sideline... today I had a potential customer call regarding PID DB machines and HX machines. She was a cafe owner who had her commercial machine PID'd. So, I asked her if her customers noticed an improvement in the espresso after the change. She quickly stated an affirmative. I then asked if the customers who positively responded KNEW the machine was changed or did not know. She said that she did not know and would have to ask her barista. The reason is that if the customer knows, it may be in 'their head' to see an improvement in the cup. HOWEVER, the true test is if they did not know the machine was changed and they commented an affirmative without any predication.

My case to justify.... at our last warehouse 4 years ago, I had a customer who only desired the best espresso - freshly roasted, freshly ground... the whole 9 yards. This custoemr roasted his own coffee and he knew his stuff. So, he was waiting up front in the office, and I prepared an espresso in the back for him. After he swooped it down, he stated that it was one fine cup of espresso and wanted to know what was in the blend. I advised him that it was an espresso pod made on a 110 volt pod-only machine with a vibe pump.

**Pretty much all the DB's that are popular on the market today have the BREW boiler PID'd. Some have the steam boiler PID'd as well**.

Although a good idea on paper, this should be further examined as my experience has shown that a quality commercial pressurestat will not fail whereas PID thermal sensors can be limescaled and become less effective over time. I think time will tell if this is a good idea.

With no data to prove either way and this does not need to be answered, how responsive is the PID to a drop in the steam pressure in a steam boiler.


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