Wouldn't an E61 with dedicated PID brew boiler and steam thermoblock be better than HX? - Page 2

April 11th, 2018, 1:54 pm

Nunas wrote:Maybe. But maybe you would prefer a DB with a PID? You would achieve the exact temperatures you choose for both steaming and brewing. I wanted a DB, but budget forced me to an HX. Like you, I had a fairly long learning curve and thought I'd made a mistake. But, now that I'm used to the HX it seems second nature to me when using it. Sounds odd, but I sometimes kind of space out and not even think about what I'm doing. I don't worry about dumping water, as I have an RO with adjustable bypass in the basement plumbed to the espresso bar. On the bar I have a typical RO inverted-J spigot. Refilling is simple, as I slip a piece of poly hose over the end of the spigot, hold the other end over the reservoir fill hole and turn on the tap. If I had to lug 5-gallon carboys of water for my espresso then water waste might be more important to me .

Slightly off topic, but I are you not remineralizing the RO water? I thought straight RO or distilled is a no-no.

#12: Post by **bluesman** » April 11th, 2018, 2:30 pm

Tonefish wrote:Assuming that steam temperature, once high enough, isn't nearly as important as brew temperature, why wouldn't it be better to have a nice adjustable PID brew boiler and a thermoblock for steam rather than an HX arrangement?

Jim Schulman answered that question 8 years ago in a thread about the Pasquini Livietta (a machine I once considered and was talked out of by a Pasquini dealer at about that time):

another_jim wrote:The Pasquini is a dual thermoblock machine, one for heating the espresso water, and one for the steam. A thermoblock is an instant heater with relatively poor controls, and in the 110V US, inadequate heating capacity. Thermoblock machines usually cost around $120 to $250, are made by Krups or Capresso and make poor espresso and steamed milk.

Granted, this one is a rebadged Quickmill, is of higher quality, and makes semi-competent espresso. But the basic flaws are still there (Quickmill itself is loath to sell these dual thermoblock models in the US). You can buy two Krups machines, set one on espresso and one on steam, and save yourself $700. Alternatively, for $1K, you can buy one of four heat exchanger machines which make good espresso and have real steaming power, the Nuova Simonelli Oscar, the Expobar Office, and two Bezzera models. A few hundred more will get you the pick of a dozen or so machines.

That's why so bad.

The problem of pumping 200 degree water to the thermoblock has already been raised by Maurice.

#13: Post by **Nunas** » April 11th, 2018, 4:38 pm

Slightly off topic, but I are you not remineralizing the RO water? I thought straight RO or distilled is a no-no.

Yes, off topic, so if this spawns any volume of discussion lets start a new thread. Anyway, in response to your question, I used pure RO water in our motor yacht (from the desaliniser) and motorhome RO (both very low TDS) for years without trouble. Here in Oliver, we have very hard city water. So, the RO water generally exits at about 25 ppm. Sometimes they change wells and the TDS drops a bit, so I just open up a needle valve on the bypass line to compensate. Most of the time the needle valve is closed, as we find 25 PPM to be fine. Some people comment about this in several regards. First, taste...I've tried everything from less than 5 ppm to over 100 ppm and can't really detect much difference. Perhaps my taste buds are not the best

. The second is the sensor for boiler filling. I've never had an overfill. I think I'd know, as we make about 75% milk drinks and would have water in the steam. Even 5 ppm is detected in my machine. I hypothesize that while this often cited issue is a possible problem, in practice I suspect it rarely happens. It may be that it happened once, or someone opined that it might be a theoretical issue, but I'm unaware of any first-hand reports. Lastly, I'm told that I'll have leaching of my equipment. Again, that has not been my experience, although it is obviously possible in theory.

#14: Post by **tdusmoha** » April 14th, 2018, 1:43 pm

If we bottom line HX vs PID, one requires temperature surf and the other is near exact. The flush routine will is the temp surfing mechanism of the HX design. The desired temperature is achieved by playing with the duration of the flush and the 'wait' before brewing. With experience, the barista can master these timings and achieve very consistent temperatures. So both designs are capable of reproducing consistent brew temperatures, just that PID is less work and a bit more certain, although most PIDs are only accurate to 1deg.

The fact that with the experience both designs can produce similar results, what is the hype all about? Well I'm glad you asked

HX machines are known to produce a humped temperature profile across a shot, while PID produces a more linear profile. In other words, if you plot the water temperature during the shot against time, HX will give a curve that increases sharply at the beginning and decreases and smoothes after. Of course, there's an impact on the espresso taste. The question of which is better is a whole new debate!

Source: The Professional Barista Handbook by Scott Rao

Personally I choose the PID design as there's always the risk of hit & miss with temperature surf. Still waiting for my Bezzera Unica, so can't tell more yet.

April 14th, 2018, 4:33 pm

tdusmoha wrote:... HX machines are known to produce a humped temperature profile across a shot, while PID produces a more linear profile. In other words, if you plot the water temperature during the shot against time, HX will give a curve that increases sharply at the beginning and decreases and smoothes after. Of course, there's an impact on the espresso taste. The question of which is better is a whole new debate!

Good point Tariq. Thanks!

Curious though, as I see this is a single boiler you are comparing to (Unica) ... assuming you brew first, and then assuming that you steam afterwards, how long does it take when you switch the boiler to steam, to get the steam? And how good is the steam?

#16: Post by **tdusmoha** » April 15th, 2018, 1:56 pm

Tonefish wrote: Curious though, as I see this is a single boiler you are comparing to (Unica) ... assuming you brew first, and then assuming that you steam afterwards, how long does it take when you switch the boiler to steam, to get the steam? And how good is the steam?

Not sure about the Unica as i've not receive it yet. On the Gaggia Classic, you can check it out here: http://www.youtube.com/watch?v=RUbptX2wEgs

#17: Post by **henkc** » April 21st, 2018, 4:58 am

What I haven't seen discussed much is the one big advantage of thermoblocks. They heat up very quickly. The way they work - on demand heating - is also a great deal more energy efficient than keeping water hot and so on. https://onlinelibrary.wiley.com/doi/pdf ... 10.00971.x

I'm not a stranger to thermoblocks in other applications. I've used them a lot in laboratory applications, where we sometimes need to maintain temperatures to 0.1°C over periods of hours to days, create temperature profiles which respond to various sensors and conditions and so on. Here thermoblocks have made life much much easier. Granted, these devices cost a great deal more than a Breville or superautomatic and can't make coffee.

The problem I see here is that the comparison is always made between a thermoblock machine designed down to a price which is typically around a third or less of the price of an entry level HX. Are there any really high-end thermoblock machines?

April 21st, 2018, 2:54 pm

henkc wrote:What I haven't seen discussed much is the one big advantage of thermoblocks. They heat up very quickly. The way they work - on demand heating - is also a great deal more energy efficient than keeping water hot and so on. https://onlinelibrary.wiley.com/doi/pdf ... 10.00971.x
The problem I see here is that the comparison is always made between a thermoblock machine designed down to a price which is typically around a third or less of the price of an entry level HX. Are there any really high-end thermoblock machines?

I think you are absolutely correct! Between the stigma associated with being in the cost-cutting/corner-cutting machines, and the anemic performance of their steam production in some of those attempts, it can be hard to think they may be a positive option. I've been wondering if one of the most progressive new attempts at superior espresso making, the Decent, isn't using a quality thermoblock in a likely approaching optimal way. I also believe that there bay be a potential niche here to leverage the advantages of a dedicated PID'd brew boiler without the cost of a second boiler, if done well.

#19: Post by **Jake_G** » April 24th, 2018, 8:42 am

After thinking about this quite a bit, I think the ideal solution could be relatively simple. Obviously, stepping up to a saturated group is ultimate, but there is still room for E61 improvement without too much work.

Take a standard HX machine and install a dual channel PID controller. You use the "brew" temperature setpoint to maintain a steady boiler temperature that gives you ideal brew temp through the HX with minimum (or zero) need for cooling flushes, with no regard for diminished steaming performance at lower boiler temps.

You then take the "steam" temperature setpoint from the PID and use it to control a thermoblock style heater that is installed between the boiler and the steam valve, with a check valve installed between the boiler and thermoblock. You should be able to set the steam temperature as high as you like on the thermoblock for superheated, dry steam with the check valve isolating the HX brew boiler from back flow. When the steam valve is opened, superheated steam exits, dropping the pressure in the the steam heater. At the lower temp of the brew boiler, the steam being fed to the steam heater should be wet enough for a properly sized heater to get a significant boost in volume and velocity by vaporizing the water droplets, resulting in higher quality steam. This could also be managed by raising the water level in the boiler to ensure the steam entering the heater is wet enough to get the desired results.

A test would be needed to verify, but I believe the low pressure of the brew boiler should be sufficient to keep a system like this fed with wet steam without the need to run the pump when the valve is open. For safety reasons, you would probably want a microswitch that would lower the heater setpoint when the steam valve is closed to prevent boiling the heater dry over time, but I suppose as long as the heater is controlled based on its own internal temperature, and you dont exceed its rated temp, this might be a moot point... The same micro switch could also be used to inject a small metered jet of fresh water right behind the check valve when the steam valve is opened, as well. The introduction of water would initiate flash condensation of the steam on the heater side and a localized pressure drop, which would draw in steam from the boiler and keep the system fed if the boiler didn't provide enough oomph on its own.

Alternatively, you could install the heater in the tea wand circuit and feed it pure water, but this would require a larger steam heater.

How to test this...

Cheers!

- Jake

April 24th, 2018, 10:03 am

Yes, I like the lower pressure brew boiler feed approach, and if it works, no need for a pump for high temperature water to feed the steam thermoblock ... which would likely be a deal breaker. I would expect this could possibly compete with dual boiler performance at HX+ prices. Not looking to build it myself, just wondering why someone hasn't.

Jake, do you know if Decent is using thermoblocks?