Could 0,2BAR be the cause of today's good coffee or was it just temp surf coincidence?

Need help with equipment usage or want to share your latest discovery?
marteccino
Posts: 26
Joined: January 27th, 2018

Postby marteccino » Feb 11, 2018, 9:06 am

ok, since i still don't have any thermometer to measure the temperature of the group head, nor I am too familiar with rebound time between shots and flushes and doing on average 5-7seconds long flush post hissing water, while running 1,2 BAR upper cycle range boiler pressure, I noticed that coffee sometimes tasted a bit aggressive in terms of bitterness, so yesterday evening i was trying to search whether lowering the pressure in a boiler can help to decrease the temp of water in a group head and also decrease the amount of water flushed that in my opinion is a waste of both energy and resources
but based on some discussions I read, I found that it won't help much and that the water is gonna be about the same temperature in the brew head due to the heat exchanger regardless what the pressure/temperature is in the boiler....
nevertheless, today I tried and adjusted the pressure stat just a tiny bit left and I could see pressure lowered by about 0,2BARS (the lower cycle is 0,8 and upper about 1BAR) and the result was less bitterness and much more nutty flavour of the coffee with only short flushes (2-4seconds) where I had 4 shots of espressos in the morning and I was still craving for more....

but the question is, was I just lucky with temp surfing and hit the right temp, or did the lowering the boiler pressure really lowered the temp in the brew head resulting in a less bitter shots?
PS:I had few shots tasting like this before, but it was hit and miss even tho it was still very much acceptable and always liked the taste, but just today after lowering the pressure was just much more smooth

PS2: I don't do milk drinks, hence I am even contemplating to go to the single boiler with pid such as bezzera unica, once HX will require too much flushing or fiddling with temp, so therefore, I am trying things I can minimize it

pizzaman383
Posts: 729
Joined: May 14th, 2011

Postby pizzaman383 » Feb 11, 2018, 9:37 am

That 0.2 bar difference translates into a 5-6 degree F difference in boiler temperature. I am very sensitive to sour and bitterness so I can definitely taste the difference 5-6 degrees of change in temperature brings to the espresso. That might be the difference.

Because of my sensitivity (and I'm not saying it's a good thing it just is what it is) I prefer a PID-controlled double boiler and group-head temperature displays so that I can get the exact temperature I'm looking for as I pull a shot.
Curtis
LMWDP #551

marteccino
Posts: 26
Joined: January 27th, 2018

Postby marteccino » Feb 11, 2018, 5:49 pm

yes that's what i am trying to establish, whether to get a single boiler with PID (i don't do milk drinks, so not sure double boiler would make any sense)
also, i will be adding a thermometer to the group head too, but i am also interested to reduce the cooling flushes as much as I can, so the question is WHAT IS THE BEST BOILER PRESSURE TO ACHIEVE DESIRED TEMP AT GROUP HEAD WITH MINIMUM FLUSHED WATER, and whether there is such a thing, because as I said, people claim heat exchanger will be sending the same water temp to the head regardless of the boiler pressure, and since I have nowhere to measure it, I am trying to find out if some people here are running specific boiler pressure solely for that reason while preparing only espresso shots...


ps:i am still kind of shocked that almost everybody is more concerned with power of steam than the things that i talk about tbh

Nunas
Posts: 533
Joined: June 4th, 2015

Postby Nunas » Feb 11, 2018, 7:50 pm

Could 0,2BAR be the cause of today's good coffee or was it just temp surf coincidence?

Yes, it is coincidence. While the boiler pressure affects the temperature of the boiler directly, the duration of the cooling shot has far more effect in the PF. Your plan to get a thermometer onto the E-61 is definitely the right way to go IMHO.

Turning to tuning the machine to your needs, your instincts are correct. Given that you do not use the prodigious steamer (reviewers report it is one of the best for a bargain HX), turning down the boiler pressure will definitely reduce the amount of time for the cooling flush. I bet that even at 1-bar, you still have plenty of steam; I'd try it another 0.2 lower. You can always turn it back up :).

I think you already have the right machine, once you get it tuned. Different coffees need different temperatures for optimum results and surfing the curve once you have a thermometer would be child's play. Single boiler with a PID would also work, especially if you do a lot of shots in a row. Going DB would not net you anything since you only pull shots and don't steam.

My 2-cents :D

User avatar
HB
Admin
Posts: 17169
Joined: April 29th, 2005

Postby HB » Feb 11, 2018, 9:12 pm

marteccino wrote:...people claim heat exchanger will be sending the same water temp to the head regardless of the boiler pressure

That's somewhere between misleading and flat-out wrong. From the Newbie Introduction to Espresso:



Ideal brew temperature management by HX espresso machine type covers the same topic as in the video above. TLDR: You need to know what kind of HX espresso machine you have before following a particular flush regiment. In my experience, new owners typically forget to flush, flush way too much, or don't allow enough recovery time. Then they blame the equipment. :wink:
Dan Kehn

marteccino
Posts: 26
Joined: January 27th, 2018

Postby marteccino » Feb 13, 2018, 3:46 pm

oh well, i have seen that video and it's a great discussion, but as a newbie i need to listen to that again and I am not sure what kind of HX I have, only that it has 2liter copper boiler and 1300Watt heater....vibration pump and the usual mater xp110 termostat...

and nunas suggest i further reduce the pressure to 0,8BAR, well, I might try that, and so what kind of recovery time I should expect with that kind of pressure?

Nunas
Posts: 533
Joined: June 4th, 2015

Postby Nunas » Feb 13, 2018, 8:24 pm

and nunas suggest i further reduce the pressure to 0,8BAR, well, I might try that, and so what kind of recovery time I should expect with that kind of pressure?


I'm not sure I can answer this question properly, as I've never tried 0.8 bar. But, I think with the nice big boiler in your machine, recovery time at any reasonable pressure would be very quick. I run my machine at about 0.9 bar because the Magister needs a long cooling flush. Even at 0.9, to get the temperature down to around 85 to 90 in the PF (about 3 degrees higher on the EricS thermometer), which is the range I like for most of my coffees, the flush takes about 20-seconds. Unlike you, I do a lot of steaming, or I'd also drop the pressure. Of course, every brand/model of HX is different in this regard. Once I flush to get the temperature right, it will drop a bit more on the first pull, but after that, subsequent pulls are quite stable. That is, I don't have to wait any appreciable time for any recovery...just the amount of time to grind and tamp a new PF full. Usually, I pull only two or three doppios in a row; so I can't say how stable it would be if I pulled more. I'm guessing that it (and yours) will be very stable. We heat such low volumes for our shots that the reheating process through a large boiler full of >100-degree water has to be quick. Also, bear in mind that no water exits the boiler, as the brew water comes from the reservoir, through the HX to the group head. A typical 1300 Watt element, if asked to boil a couple of ounces of water would do that nearly instantly. But, this is all conjecture. Please let us know how it goes at 0.8 bar :)

marteccino
Posts: 26
Joined: January 27th, 2018

Postby marteccino » Feb 15, 2018, 5:44 pm

oh wow what 20 seconds!!??that would be way too long for me and waste of my expensive packaged water along with the filter that i need to change asap omg....anyhow, it is a news to me that water flows directly from reservoir through HX to the head and not from the boiler....it seems i still don't understand the HX architecture, i thought it is some pipe inside of a boiler that will change the temp of the water that flows there from the boiler....

last thing, i haven't done backflush yet after about hmm 40-50 coffee??? i just don't have the blind basket omg...i need to get it asap, because today i remove the portafilter and there was a water inside, unlike before when it was nice and dry, so i hope I didn't shot the three way valve....

btw, that water thing softening is pain in the b...considering we have very hard water here.....

marteccino
Posts: 26
Joined: January 27th, 2018

Postby marteccino » Feb 15, 2018, 5:47 pm

Ideal brew temperature management by HX espresso machine type covers the same topic as in the video above. TLDR: You need to know what kind of HX espresso machine you have before following a particular flush regiment. In my experience, new owners typically forget to flush, flush way too much, or don't allow enough recovery time. Then they blame the equipment. :wink:[/quote]



thanks for a great tip Dan, you are a celebrity here! anyhow, When I watched the video I scrolled to read the comments but they are disabled....pity, because there are sometimes useful comments as well. i think it would add to the discussion if they are allowed, but it's ur business, just an idea

Nunas
Posts: 533
Joined: June 4th, 2015

Postby Nunas » Feb 15, 2018, 6:31 pm

....anyhow, it is a news to me that water flows directly from reservoir through HX to the head and not from the boiler....it seems i still don't understand the HX architecture

It's really quite simple. The pump sends water to the boiler when the sensor tells the pump the water is low. The heater boils the water until the pressure sensor tells it the pressure is right (about 1 bar). Steam is drawn off the top of the boiler for the steaming wand. Hot water is drawn from the boiler from lower down, for the hot water wand (if fitted). The HX is just a pipe that runs through the boiler. Water for the shot is pumped in on one side of the pipe; it travels through the pipe where the super hot water in the boiler heats it up; then the heated water exits through the other end of the pipe to the group head. No boiler water ever goes into the coffee.

last thing, i haven't done backflush yet after about hmm 40-50 coffee??? i just don't have the blind basket omg...i need to get it asap, because today i remove the portafilter and there was a water inside, unlike before when it was nice and dry, so i hope I didn't shot the three way valve...

No need to panic. Until you buy a blind basket, if you can find some flat flexible rubber, like from an inner tube for a car tyre, just cut a disk to fit the bottom of your portafilter. You can buy these from many coffee equipment suppliers and some people use them instead of a blind basket. Some of the Breville machines come with these as standard equipment (or at least they used to).

that water thing softening is pain in the b...considering we have very hard water here.....

This is a huge subject all its own. The cheapest and easiest thing to do is to buy a filter that fits on the end of the pick up hose in the water reservoir. These are little ion exchangers like in big water softeners. They need to be reconditioned every few weeks by soaking them in salt water then flushing them. Do a search on H-B for water and you'll find enough information to keep you reading for a month :lol:

 
Sponsored by klatchroasting.com
www.klatchroasting.com: USBC champion, voted 2009 'best micro-roaster'